Are the Benefits of Organic Food Underrated or Overrated?

Vegsource.jpeg

Pesticides have been classified as probable carcinogens for 25 years. Different pesticides have been associated with different cancers through a variety of mechanisms, including genetic damage--direct hits to our DNA or chromosomes--and epigenetic modification, changes in the way our genes are expressed. These effects have been documented in workers who are spraying the pesticides, but exposure to pesticide residues that remain on food is much smaller.

More recently, higher cancer rates have also been noted in people who live in areas where pesticides are heavily sprayed, but what about the food we buy at the store? Organic fruits and vegetables have fewer pesticides, but even the levels on conventional produce are generally well below acceptable limits. There is still scientific controversy about the safety of some pesticides even under the regulatory limits, however, given the possible additive effects of the mixture of pesticides to which we're exposed. The pesticide approval process also doesn't take into account toxic breakdown products such as dioxins that can form once pesticides are released into the environment.

Cadmium is another issue. In the largest review to date, involving hundreds of studies, not only did organic foods have more antioxidant phytonutrients, but lower concentrations of cadmium. Cadmium is one of three highly toxic heavy metals (along with lead and mercury) found in the food supply. Cadmium accumulates in the body, so we should try to keep intake as low as possible. Organic crops only have about half the cadmium, which is thought to come from the phosphate fertilizers that are added to conventional crops.

Of course, not all organic foods are healthy. The organic food industry is now worth tens of billions of dollars, and they didn't get that way just selling carrots. We can now buy pesticide-free potato chips and organic jelly beans. Organic foods can be even worse because, for example, people falsely judge organic Oreo cookies to have fewer calories than conventional Oreos, and so may eat more. Forgoing exercise was deemed more acceptable when the person had just chosen an organic dessert rather than a conventional one. In fact, leniency toward forgoing exercise was slightly greater after choosing an organic dessert than after eating no dessert at all--organic cookies were effectively viewed as having negative calories! Organic junk food is still junk food.

Not only do people tend to overestimate the nutritional benefits of organic foods, they also overestimate the risks of pesticides. People think that as many people die from pesticide residues on conventional food as die in motor vehicle accidents in the United States. Surveys have found organic food buyers may think eating conventional produce is almost as bad as smoking a pack of cigarettes. That kind of thinking is dangerous because it could potentially lead to a decrease in overall fruit and vegetable consumption.

If just half of the U.S. population were to increase fruit and vegetable consumption by a single serving a day, an estimated 20,000 cancer cases might be avoided each year. That's how powerful produce may be. But, because the model was using conventional fruits and veggies, the pesticide burden from those extra fruits and vegetables might result in 10 additional cancer cases. So overall, if half of us ate one more serving, we'd just prevent 19,990 cases of cancer a year.

Now that was a paper written by scientists-for-hire paid for by the Alliance for Food and Farming, which is a bunch of conventional produce growers, so they probably exaggerated the benefits and minimized the risks, but I think the bottom line is sound. We get a tremendous benefit from eating conventional fruits and vegetables that far outweighs whatever tiny bump in risk we may get from the pesticides. Why not reap the benefits without the risk and choose organic? Great! But we should never let concern about pesticides stop us from stuffing our face with as many fruits and vegetables as possible.

My video, Are the Benefits of Organic Food Underrated or Overrated?, was the final installment of a 5-part series on organics. The first four videos are:

I've covered the issue of cadmium in our diet before in Cadmium and Cancer: Plant vs. Animal Foods and Male Fertility and Diet. Heavy metals are found concentrated in seafood and organ meats, but can also be found in certain supplements and protein powders.

In health,

Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Image Credit: Sally Plank / Flickr. This image has been modified.

Original Link

Are the Benefits of Organic Food Underrated or Overrated?

Vegsource.jpeg

Pesticides have been classified as probable carcinogens for 25 years. Different pesticides have been associated with different cancers through a variety of mechanisms, including genetic damage--direct hits to our DNA or chromosomes--and epigenetic modification, changes in the way our genes are expressed. These effects have been documented in workers who are spraying the pesticides, but exposure to pesticide residues that remain on food is much smaller.

More recently, higher cancer rates have also been noted in people who live in areas where pesticides are heavily sprayed, but what about the food we buy at the store? Organic fruits and vegetables have fewer pesticides, but even the levels on conventional produce are generally well below acceptable limits. There is still scientific controversy about the safety of some pesticides even under the regulatory limits, however, given the possible additive effects of the mixture of pesticides to which we're exposed. The pesticide approval process also doesn't take into account toxic breakdown products such as dioxins that can form once pesticides are released into the environment.

Cadmium is another issue. In the largest review to date, involving hundreds of studies, not only did organic foods have more antioxidant phytonutrients, but lower concentrations of cadmium. Cadmium is one of three highly toxic heavy metals (along with lead and mercury) found in the food supply. Cadmium accumulates in the body, so we should try to keep intake as low as possible. Organic crops only have about half the cadmium, which is thought to come from the phosphate fertilizers that are added to conventional crops.

Of course, not all organic foods are healthy. The organic food industry is now worth tens of billions of dollars, and they didn't get that way just selling carrots. We can now buy pesticide-free potato chips and organic jelly beans. Organic foods can be even worse because, for example, people falsely judge organic Oreo cookies to have fewer calories than conventional Oreos, and so may eat more. Forgoing exercise was deemed more acceptable when the person had just chosen an organic dessert rather than a conventional one. In fact, leniency toward forgoing exercise was slightly greater after choosing an organic dessert than after eating no dessert at all--organic cookies were effectively viewed as having negative calories! Organic junk food is still junk food.

Not only do people tend to overestimate the nutritional benefits of organic foods, they also overestimate the risks of pesticides. People think that as many people die from pesticide residues on conventional food as die in motor vehicle accidents in the United States. Surveys have found organic food buyers may think eating conventional produce is almost as bad as smoking a pack of cigarettes. That kind of thinking is dangerous because it could potentially lead to a decrease in overall fruit and vegetable consumption.

If just half of the U.S. population were to increase fruit and vegetable consumption by a single serving a day, an estimated 20,000 cancer cases might be avoided each year. That's how powerful produce may be. But, because the model was using conventional fruits and veggies, the pesticide burden from those extra fruits and vegetables might result in 10 additional cancer cases. So overall, if half of us ate one more serving, we'd just prevent 19,990 cases of cancer a year.

Now that was a paper written by scientists-for-hire paid for by the Alliance for Food and Farming, which is a bunch of conventional produce growers, so they probably exaggerated the benefits and minimized the risks, but I think the bottom line is sound. We get a tremendous benefit from eating conventional fruits and vegetables that far outweighs whatever tiny bump in risk we may get from the pesticides. Why not reap the benefits without the risk and choose organic? Great! But we should never let concern about pesticides stop us from stuffing our face with as many fruits and vegetables as possible.

My video, Are the Benefits of Organic Food Underrated or Overrated?, was the final installment of a 5-part series on organics. The first four videos are:

I've covered the issue of cadmium in our diet before in Cadmium and Cancer: Plant vs. Animal Foods and Male Fertility and Diet. Heavy metals are found concentrated in seafood and organ meats, but can also be found in certain supplements and protein powders.

In health,

Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Image Credit: Sally Plank / Flickr. This image has been modified.

Original Link

Benefits of Nutritional Yeast to Prevent the Common Cold

Benefits of Nutritional Yeast to Prevent the Common Cold.jpeg

Natural immunomodulators that can help regulate our immune system without side-effects have been sought for centuries, and all the while they've been sitting in the produce aisle. Plants produce thousand of active compounds, many of which modulate our immune system, but we can't forget the fungi (see Boosting Immunity While Reducing Inflammation).

Mushrooms have used for centuries as folk remedies, and for good reason. Some have been shown to boost immune function, so much so that a type of fiber found in shiitake mushrooms is approved for use as adjunct chemotherapy, injected intravenously to help treat a variety of cancers by rallying our immune defenses.

More than 6,000 papers have been published on these so-called beta glucans, but almost all of the data about preventing infections had come from petri dish or lab animal studies, until a few years ago when a series of experiments on athletes showed beneficial effects in marathon runners (see Preserving Immune Function in Athletes With Nutritional Yeast). What about the rest of us? We didn't know... until now.

As I explore in my video, Nutritional Yeast to Prevent the Common Cold, beta glucan fiber found in baker's, brewer's and nutritional yeast helps to maintain our body's defense against pathogens even in nonathletes, according to a double-blind, randomized, placebo-controlled trial. The recurrence of infections with the common cold was reduced by 25% in those that ate the equivalent of about a spoonful of nutritional yeast a day, and had fewer cold-related sleeping difficulties when they did get sick.

What about half a spoonful a day? Still worked! Subjects experienced a big drop in common cold incidence and a reduction in symptoms as well. Why is this? This study found that not only were upper respiratory infection symptoms diminished, but that mood states appeared to improve, for example a significant boost in feelings of "vigor." So the researchers suggest that maybe the yeast fiber is able to counteract the negative effects of stress on the immune system.

In terms of side-effects, two folks reported stomachaches, but they were both in the placebo group.

Unlike antibiotics and antivirals, which are designed to kill the pathogen directly, these yeast compounds instead appear to work by stimulating our immune defenses, and as such don't share the same antibiotic side effects. They stimulate our immune defenses presumably because our body recognizes them as foreign. But if it's treated like an invader, might it trigger an inflammatory response? Turns out these fiber compounds may actually have an anti-inflammatory effect, suggesting nutritional yeast may offer the best of both worlds, boosting the infection fighting side of the immune system while suppressing inflammatory components.

Yeast is high in purines, so those with gout, uric acid kidney stones, and new organ transplant recipients may want to keep their intake to less than a teaspoon a day. But is there any downside for everyone else? In California some packages of nutritional yeast are slapped with prop 65 warning stickers, suggesting there's something in it exceeding cancer or birth defect safety limits. I called around to the companies and it turns out the problem is lead. California state law says a product cannot contain more than half of a microgram of lead per daily serving, so I contacted the six brands I knew about and asked them how much lead was in their products.

KAL originally said "<5 ppm," but when we called back they said "<3 ppm." Even if it's 3, that translates into less than 45 micrograms per serving, nearly a 100 times more than the California limit. But perhaps that's better than Bob's Red Mill or Frontier Coop, who evidently don't test at all. But at least they got back to me. Redstar brand failed to respond to multiple attempts to contact them. Now Foods said they test for lead and claim that at least their recent batches meet the less than a half a microgram California standard. Unfortunately, despite repeated requests they would not provide me with documentation to substantiate their numbers. My favorite response was from Bragg's who sent me the analysis certificate from the lab showing less than 0.01 ppm, which means at most less than half the California standard, which I believe is the most stringent in the world. To put the numbers in context, in determining how much lead manufacturers can put into candy likely to be frequently consumed by small children, the Food and Drug Administration would allow about 2 micrograms a day in the form of lollipops, but as far as I'm concerned the less lead the better.

I was so frustrated by the lack of transparency I decided to test them for lead myself. NutritionFacts.org hired an independent lab to conduct our own tests for lead and shipped out 8 samples of nutritional yeast in their original package. The lab used standard practices for lead testing known as Official Methods of Analysis set by AOAC International. Lab technicians determined the lead values based on California Prop 65 standards. Here are the results from the brands we tested:

Bob's Red Mill - Test report shows no detectable lead (<0.01 ppm).

Bragg - Test report shows no detectable lead (< 0.01 ppm).

Dr. Fuhrman - Test report shows no detectable lead (< 0.01 ppm).

Frontier Coop - Test report shows lead levels at 0.021 ppm. It would take six tablespoons a day (based on the manufacture's listed density) to exceed the California Office of Environmental Health Hazard Assessment Maximum Allowable Dose Level (MADL) for chemicals causing reproductive toxicity.*

KAL - Test report shows lead levels at 0.011 ppm. It would take seven tablespoons a day to exceed the MADL.*

NOW Foods - Test report shows no detectable lead (< 0.01 ppm).

Red Star - Test report shows no detectable lead (< 0.01 ppm).

Whole Foods - Test report shows lead levels at 0.012 ppm. It would take six tablespoons a day to exceed the MADL.*

So what do all those numbers mean? None of the brands tested exceeded California prop 65 standards. No matter what brand, consuming a typical serving (2 tablespoons) per day is still well within safe limits.

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

* The Maximum Allowable Dose Level for lead as a developmental toxin is 0.5 micrograms a day. How are MADL's calculated? Basically scientists figure out what the "no observable effect level" is, the level at which no birth defects or reproductive toxicity can be found, and then introduce a 1000-fold safety buffer. So for example, let's say there's some chemical that causes birth defects if expectant moms are exposed to two drops of the chemical a day, but there's no evidence that one drop a day is harmful. Do they set the Maximum Allowable Dose Level at one drop? No, they set it at 1/1000th of a drop to account for scientific uncertainty and to err on the side of caution. So by saying six tablespoons a day of nutritional yeast may exceed the MADL is in effect saying that the level of lead found in 6,000 tablespoons of nutritional yeast may cause birth defects. Like mercury, though, as far as I'm concerned the less lead exposure the better. I hope this will inspire companies to do further testing to see if the levels we found were just flukes.

Image Credit: Sally Plank / Flickr. This image has been modified.

Original Link

Benefits of Nutritional Yeast to Prevent the Common Cold

Benefits of Nutritional Yeast to Prevent the Common Cold.jpeg

Natural immunomodulators that can help regulate our immune system without side-effects have been sought for centuries, and all the while they've been sitting in the produce aisle. Plants produce thousand of active compounds, many of which modulate our immune system, but we can't forget the fungi (see Boosting Immunity While Reducing Inflammation).

Mushrooms have used for centuries as folk remedies, and for good reason. Some have been shown to boost immune function, so much so that a type of fiber found in shiitake mushrooms is approved for use as adjunct chemotherapy, injected intravenously to help treat a variety of cancers by rallying our immune defenses.

More than 6,000 papers have been published on these so-called beta glucans, but almost all of the data about preventing infections had come from petri dish or lab animal studies, until a few years ago when a series of experiments on athletes showed beneficial effects in marathon runners (see Preserving Immune Function in Athletes With Nutritional Yeast). What about the rest of us? We didn't know... until now.

As I explore in my video, Nutritional Yeast to Prevent the Common Cold, beta glucan fiber found in baker's, brewer's and nutritional yeast helps to maintain our body's defense against pathogens even in nonathletes, according to a double-blind, randomized, placebo-controlled trial. The recurrence of infections with the common cold was reduced by 25% in those that ate the equivalent of about a spoonful of nutritional yeast a day, and had fewer cold-related sleeping difficulties when they did get sick.

What about half a spoonful a day? Still worked! Subjects experienced a big drop in common cold incidence and a reduction in symptoms as well. Why is this? This study found that not only were upper respiratory infection symptoms diminished, but that mood states appeared to improve, for example a significant boost in feelings of "vigor." So the researchers suggest that maybe the yeast fiber is able to counteract the negative effects of stress on the immune system.

In terms of side-effects, two folks reported stomachaches, but they were both in the placebo group.

Unlike antibiotics and antivirals, which are designed to kill the pathogen directly, these yeast compounds instead appear to work by stimulating our immune defenses, and as such don't share the same antibiotic side effects. They stimulate our immune defenses presumably because our body recognizes them as foreign. But if it's treated like an invader, might it trigger an inflammatory response? Turns out these fiber compounds may actually have an anti-inflammatory effect, suggesting nutritional yeast may offer the best of both worlds, boosting the infection fighting side of the immune system while suppressing inflammatory components.

Yeast is high in purines, so those with gout, uric acid kidney stones, and new organ transplant recipients may want to keep their intake to less than a teaspoon a day. But is there any downside for everyone else? In California some packages of nutritional yeast are slapped with prop 65 warning stickers, suggesting there's something in it exceeding cancer or birth defect safety limits. I called around to the companies and it turns out the problem is lead. California state law says a product cannot contain more than half of a microgram of lead per daily serving, so I contacted the six brands I knew about and asked them how much lead was in their products.

KAL originally said "<5 ppm," but when we called back they said "<3 ppm." Even if it's 3, that translates into less than 45 micrograms per serving, nearly a 100 times more than the California limit. But perhaps that's better than Bob's Red Mill or Frontier Coop, who evidently don't test at all. But at least they got back to me. Redstar brand failed to respond to multiple attempts to contact them. Now Foods said they test for lead and claim that at least their recent batches meet the less than a half a microgram California standard. Unfortunately, despite repeated requests they would not provide me with documentation to substantiate their numbers. My favorite response was from Bragg's who sent me the analysis certificate from the lab showing less than 0.01 ppm, which means at most less than half the California standard, which I believe is the most stringent in the world. To put the numbers in context, in determining how much lead manufacturers can put into candy likely to be frequently consumed by small children, the Food and Drug Administration would allow about 2 micrograms a day in the form of lollipops, but as far as I'm concerned the less lead the better.

I was so frustrated by the lack of transparency I decided to test them for lead myself. NutritionFacts.org hired an independent lab to conduct our own tests for lead and shipped out 8 samples of nutritional yeast in their original package. The lab used standard practices for lead testing known as Official Methods of Analysis set by AOAC International. Lab technicians determined the lead values based on California Prop 65 standards. Here are the results from the brands we tested:

Bob's Red Mill - Test report shows no detectable lead (<0.01 ppm).

Bragg - Test report shows no detectable lead (< 0.01 ppm).

Dr. Fuhrman - Test report shows no detectable lead (< 0.01 ppm).

Frontier Coop - Test report shows lead levels at 0.021 ppm. It would take six tablespoons a day (based on the manufacture's listed density) to exceed the California Office of Environmental Health Hazard Assessment Maximum Allowable Dose Level (MADL) for chemicals causing reproductive toxicity.*

KAL - Test report shows lead levels at 0.011 ppm. It would take seven tablespoons a day to exceed the MADL.*

NOW Foods - Test report shows no detectable lead (< 0.01 ppm).

Red Star - Test report shows no detectable lead (< 0.01 ppm).

Whole Foods - Test report shows lead levels at 0.012 ppm. It would take six tablespoons a day to exceed the MADL.*

So what do all those numbers mean? None of the brands tested exceeded California prop 65 standards. No matter what brand, consuming a typical serving (2 tablespoons) per day is still well within safe limits.

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

* The Maximum Allowable Dose Level for lead as a developmental toxin is 0.5 micrograms a day. How are MADL's calculated? Basically scientists figure out what the "no observable effect level" is, the level at which no birth defects or reproductive toxicity can be found, and then introduce a 1000-fold safety buffer. So for example, let's say there's some chemical that causes birth defects if expectant moms are exposed to two drops of the chemical a day, but there's no evidence that one drop a day is harmful. Do they set the Maximum Allowable Dose Level at one drop? No, they set it at 1/1000th of a drop to account for scientific uncertainty and to err on the side of caution. So by saying six tablespoons a day of nutritional yeast may exceed the MADL is in effect saying that the level of lead found in 6,000 tablespoons of nutritional yeast may cause birth defects. Like mercury, though, as far as I'm concerned the less lead exposure the better. I hope this will inspire companies to do further testing to see if the levels we found were just flukes.

Image Credit: Sally Plank / Flickr. This image has been modified.

Original Link

No More Than a Quart a Day of Hibiscus Tea

NF-May17 How Much Hibiscus Tea is Too Much?.jpeg

Over the counter antacids are probably the most important source for human aluminum exposure in terms of dose. For example, Maalox, taken as directed, can exceed the daily safety limit more than 100-fold, and nowhere on the label does it say to not take it with acidic beverages such as fruit juice. Washing an antacid down with orange juice can increase aluminum absorption 8-fold, and citric acid-the acid found naturally concentrated in lemon and limes--is even worse.

Just as sour fruits can enhance the absorption of iron (a good thing), the same mechanism they may enhance the absorption of aluminum (a bad thing). This raises the question of what happens when one adds lemon juice to tea? Previously, I concluded that the amount of aluminum in tea is not a problem for most people because it's not very absorbable (See Is There Too Much Aluminum in Tea?). What if we add lemon? Researchers publishing in the journal Food and Chemical Toxicology found no difference between tea with lemon, tea without lemon, or no tea at all in terms of the amount of aluminum in the bloodstream, suggesting that tea drinking does not significantly contribute to aluminum getting inside the body.

The researchers used black tea, green tea, white tea, oolong tea, but what about the "red zinger" herbal tea, hibiscus? The reason hibiscus tea is called "sour tea" is because it has natural acids in it like citric acid. Might these acids boost the absorption of any hibiscus's aluminum? While a greater percentage of aluminum gets from the hibiscus into the tea water than from the other teas, there's less aluminum overall.

The real question is whether the aluminum then gets from the tea water into our bodies. We don't have that data, so to be on the safe side we should assume the worst: that hibiscus tea aluminum, unlike green and black tea aluminum, is completely absorbable. In that case, based on this data and the World Health Organization weekly safety limit, we may not want to drink more than 15 cups of hibiscus tea a day, (based on someone who's about 150 pounds). If you have a 75 pound 10-year-old, a half-gallon a day may theoretically be too much. Recent, more extensive testing highlighted in my video, How Much Hibiscus Tea is Too Much?, suggests that levels may reach level twice as high. Therefore, to be safe, no more than about two quarts a day for adults, or one quart a day for kids or pregnant women. Hibiscus tea should be completely avoided by infants under six months--who should only be getting breast milk--as well as kids with kidney failure, who can't efficiently excrete it.

There is also a concern about the impressive manganese level in hibiscus tea. Manganese is an essential trace mineral, a vital component of some of our most important antioxidant enzymes, but we probably only need about two to five milligrams a day. Four cups of hibiscus tea can have as much as 17 milligrams, with an average of about ten. Is that a problem?

One study from the University of Wisconsin found that women given 15 milligrams of manganese a day for four months, saw, if anything, an improvement in their anti-inflammatory, anti-oxidant enzyme activity. Another study using 20 milligrams a day similarly showed no adverse short-term effects, and importantly showed that the retention of dietary manganese is regulated. Our bodies aren't stupid; if we take in too much manganese, we decrease the absorption and increases the excretion. Even though tea drinkers may get ten times the manganese load (10 or 20 milligrams a day) the levels in their blood are essentially identical. There is little evidence that dietary manganese poses a risk.

These studies were conducted with regular tea, though, so we don't know about the absorption from hibiscus. To err on the side of caution we should probably not routinely exceed the reference dose of ten milligrams per day, or about a quart a day for adults and a half-quart for a 75 pound child.

I've actually changed my consumption. Given the benefits of the stuff, I was using it as a substitute for drinking water, drinking around two quarts a day. I was also blending the hibiscus petals in, not throwing them away, effectively doubling the aluminum content, and increasing manganese concentrations by about 30%. So given this data I've cut back to no more than a quart of filtered hibiscus tea a day.

Lemon can actually boost the antioxidant content of green and white tea. See Green Tea vs. White. For a comparison of their cancer-fighting effects in vitro, Antimutagenic Activity of Green Versus White Tea.

Before that I covered another potential downside of sour tea consumption in Protecting Teeth From Hibiscus Tea, and before that a reason we should all consider drinking it in: Hibiscus Tea vs. Plant-Based Diets for Hypertension.

For more on the iron absorption effect, see my video Risks Associated with Iron Supplements.

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: mararie / Flickr

Original Link

Aluminum Levels in Tea

NF-May12 Is There Too Much Aluminum in Tea?.jpeg

While aluminum is the third most abundant element on Earth, it may not be good for our brain, something we learned studying foundry workers exposed to particularly high levels. Although the role of aluminum in the development of brain diseases like Alzheimer's is controversial, to be prudent, steps should probably be taken to lessen our exposure to this metal.

There are a number of aluminum-containing drugs on the market (like antacids, which have the highest levels), though aluminum compounds are also added to processed foods such as anti-caking agents in pancake mix, melting agents in American cheese, meat binders, gravy thickeners, rising agents in some baking powders and dye-binders in candy. Therefore, it's better to stick to unprocessed, natural foods. Also, if you cook those natural foods in an aluminum pot, a significant amount of aluminum can leach into the food (compared to cooking in stainless steel).

When researchers tried the same experiment with tea, they got a few milligrams of aluminum regardless of what type of pot they used, suggesting that aluminum was in the tea itself. Indeed, back in the 1950's researchers noticed that tea plants tended to suck up aluminum from the soil. But it's the dose that makes the poison. According to the World Health Organization, the provisional tolerable weekly intake--our best guess at a safety limit for aluminum--is two mg per healthy kilogram of body weight per week, which is nearly a milligram per pound. Someone who weighs around 150 pounds probably shouldn't ingest more than around 20 mg of aluminum per day.

Up to a fifth of aluminum intake may come from beverages, so what we drink probably shouldn't contribute more than about four mg a day, the amount found in about five cups of green, black, or oolong tea. So should we not drink more than five cups of tea a day?

It's not what you eat or drink, it's what you absorb. If we just measured how much aluminum was in tea, it would seem as though a couple cups could double aluminum intake for the day. But if we measure the level of aluminum in people's bodies after they drink tea, it doesn't go up. This suggests that the bioavailability of aluminum in tea is low, possibly because most of the extractable aluminum in brewed tea is strongly bound to large phytonutrients that are not easily absorbed, so the aluminum just passes right through us without actually getting into our bodies. Probably more than 90 percent of the aluminum in tea is bound up.

One study out of Singapore, highlighted in my video, Is There Too Much Aluminum in Tea? did show a large spike in aluminum excretion through the urine after drinking tea compared to water. The only way for something to get from our mouth to our bladder is to first be absorbed into our bloodstream. But the researchers weren't comparing the same quantity of tea to water. They had the study subject chug down about eight and a half cups of tea, or drink water at their leisure. Therefore, the tea drinkers peed a lot more, so the aluminum content cup-for-cup was no different for tea versus water. This suggests that gross aluminum absorption from tea is unlikely and that only a little aluminum is potentially available for absorption.

So although as few as four cups of tea could provide 100 percent of our daily aluminum limit, the percentage available for absorption in the intestine may be less than 10 percent. It is therefore unlikely that moderate amounts of tea drinking can have any harmful effects--for people with normal aluminum excretion. Tea may not, however, be a good beverage for children with kidney failure, since they can't get rid of aluminum as efficiently. For most people, though, tea shouldn't be a problem.

On a special note, if you drink tea out of a can, buy undented cans. The aluminum in dented cans can leach into the liquid, boosting aluminum levels by a factor of eight while sitting on store shelves for a year.

What about the levels and absorbability of the aluminum in my other favorite type of tea? Find out in my video, How Much Hibiscus Tea is Too Much?

The tea plant also sucks up fluoride. So much so that heavy tea drinking can stain the teeth of children. See my video Childhood Tea Drinking May Increase Fluorosis Risk.

Why should we go out of our way to drink tea? See:

Is Caffeinated Tea Dehydrating? Find out by watching the video!

For more on metals in our food supply, see:

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: Toshiyuki IMAI / Flickr

Original Link

How to Reduce Your Dietary Cadmium Absorption

NF-Oct15 Cadmium and cancer- plant vs animal food .jpg

Cadmium is known as a highly toxic metal that represents a major hazard to human health. It sticks around in our body for decades because our body has no efficient way to get rid of it and may contribute to a variety of illnesses, including heart disease, cancer, and diabetes.

Most recently, data suggests that cadmium exposure may impair cognitive performance even at levels once thought to be safe. Recent studies also suggest that cadmium exposure may produce other adverse health effects at lower exposure levels than previously predicted, including increased risk of hormonal cancers. For example, researchers on Long Island estimated that as much as a third of breast cancer in the U.S. might be associated with elevated cadmium levels.

Inhalation of cigarette smoke is one of the major routes for human exposure to cadmium. Seafood consumption is another route of human exposure. The highest levels, though, are found in organ meats. But how many horse kidneys do people eat? Since people eat so few organs, grains and vegetables actually end up contributing the largest amount to our collective diets.

However, don't drop the salad from the menu yet.

Whole grains and vegetables are among the major dietary sources of fiber, phytoestrogens, and antioxidants that may protect against breast cancer. Indeed, even though the risk of breast cancer goes up as women consume more and more cadmium, and even though on paper most cadmium comes from grains and vegetables, breast cancer risk goes down the more and more whole grains and vegetables women eat. So are animal sources of cadmium somehow worse, or do the benefits of plant foods just overwhelm any adverse effects of the cadmium?

A study out of the Journal of the Medical Association of Thailand highlighted in my video, Cadmium and Cancer: Plant vs. Animal Foods, may have helped solve the mystery. It's not what we eat, it's what we absorb.

Cadmium bioavailability from animal-based foods may be higher than that from vegetable-based foods. There appears to be something in plants that inhibits cadmium absorption. In fact, researchers found when they added kale to boiled pig kidneys, they could cut down on the toxic exposure. Just one tablespoon of pig kidney, and we may exceed the daily safety limit--unless we add kale, in which case we could eat a whole quarter cup. The pronounced effects of the inhibitory factors in kale point out, as the researchers note, "the importance of vegetable foods in terms of prevention of health hazard from [cadmium] ingested as mixed diets in a real situation."

Reesearchers have concluded: "Even if a vegetarian diet contains more lead and cadmium than a mixed diet, it is not certain that it will give rise to higher uptake of the metals, because the absorption of lead and cadmium is inhibited by plant components such as fiber and phytate." Having whole grains in our stomach up to three hours before we swallow lead can eliminate 90% of absorption, thought to be due to phytates in whole grains, nuts, and beans grabbing onto it.

So vegetarians may have lower levels of lead and cadmium even though they have higher intakes.

In fact, there is a significant decrease in the hair concentrations of lead and cadmium after the change from an omnivorous to a vegetarian diet, indicating a lower absorption of the metals. Researchers took folks eating a standard Swedish diet and put them on a vegetarian diet. The vegetarians were encouraged to eat lots of whole, unrefined plant foods, with no meat, poultry, fish, and eggs. Junk food was also discouraged. Within three months on a vegetarian diet, their levels significantly dropped, and stayed down for the rest of the year-long experiment. The researchers came back three years later, three years after the subjects stopped eating vegetarian, and found that their levels of mercury, cadmium, and lead had shot back up.

Since the cadmium in plants is based on the cadmium in soil, plant-eaters that live in a really polluted area like Slovakia, which has some of the highest levels thanks to the chemical and smelting industries, can indeed build up higher cadmium levels, especially if they eat lots of plants. It's interesting that, "in spite of the significantly higher blood cadmium concentration as a consequence of a greater cadmium intake from polluted plants, all the antioxidants in those same plants were found to help inhibit the harmful effects of higher free radical production caused by the cadmium exposure." Still, though, in highly polluted areas it might be an especially good idea not to smoke or eat too much seafood or organ meats. But even if we live in the Slovak Republic's "black triangle of pollution," the benefits of whole plant foods would outweigh the risks. For people in highly polluted areas, zinc supplements may decrease cadmium absorption, but I'd recommend against multi-mineral supplements, as they have been found to be contaminated with cadmium itself.

There are other toxins in cigarette smoke also found in food. See:

Toxic metals have also been found in dietary supplements. See for example, Get the Lead Out and Heavy Metals in Protein Powder Supplements.

Mercury is also a serious problem. See:

More on pollution in seafood can be found in:

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: Julie / Flickr

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How Contaminated Are Our Children?

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In a study highlighted in my video, California Childen Are Contaminated, researchers analyzed the diets of California children ages two through seven to determine the cancer and non-cancer health effects from food contaminant exposures. It turns out food may be the primary route of exposure to toxic heavy metals, persistent pollutants, and pesticides. "Though food-borne toxic contaminants are a concern for all ages, they are of greatest concern for children, who are disproportionately impacted because they're still developing and have greater intake of food and fluids relative to their weight. Pediatric problems that have been linked to preventable environmental toxin exposures include cancer, asthma, lead poisoning, neurobehavioral disorders, learning and developmental disabilities, and birth defects."

The good news is that changing one's diet can change one's exposure. Quoting from the study, "A diet high in fish and animal products, for example, results in greater exposure to persistent pollutants like DDT and dioxins and heavy metals than does a plant-based diet because these compounds bioaccumulate up the food chain." Plants are at the bottom of the food chain. The sample of California kids, however, was not eating a plant-based diet. Cancer benchmark levels were exceeded by all 364 children for arsenic, the banned pesticide dieldrin, a metabolite of DDT called DDE, and dioxins.

Children exceeded safety levels by a greater margin than adults. This is especially of concern for children because all of these compounds are suspected endocrine disruptors and thus may impact normal development. Cancer risk ratios were exceeded by over a factor of 100 for both arsenic and dioxins.

Which foods were the worse? For preschoolers, the number one food source of arsenic was poultry, though for their parents, it was tuna. The number one source of lead was dairy, and for mercury it was seafood. And the number one source of the banned pesticides and dioxins was dairy. (See Preventing Parkinson's Disease With Diet.)

The researchers also recommended children should eat lower quantities of chips, cereal, crackers, and other crispy carbs to reduce acrylamide intake.

The California study didn't split up the groups by gender, but a similar study in Europe found that men had higher levels of some of these pollutants than women. For example, levels of the banned pesticide chlordane were higher in men, but women who never breastfed were right up there alongside men, with the lowest levels found in women who breastfed over 12 months. Therefore, it is likely that the lactation-related reduction in blood pollutant levels partly explains the lower body burdens among women compared with men. So cows can lower their levels by giving some to us, then we can pass it along to our children.

What non-cancer effects might some of these pollutants have? They can affect our immune system. Studies clearly demonstrate the "ability of dioxins and related compounds to have a long-lasting and deleterious impact on immune function." This manifests as increased incidences of respiratory infections, ear infections, cough, and sore throat. At first, most of the data was for during infancy, but now we have follow-up studies showing that the immunosuppressive effects of these toxins may persist into early childhood, so we should try to reduce our exposure as much as possible. Because these pollutants accumulate in animal fat, consuming a plant-based diet-decreasing meat, dairy, and fish consumption-may reduce exposure for children and adults alike.

These findings should come as no surprise to those who saw my video Pollutants in California Breast Tissue. For an overview see CDC Report on Environmental Chemical Exposure and President's Cancer Panel Report on Environmental Risk.

Pollutant exposure may affect the ability to have children in the first place (Male Fertility and Diet and Meat Hormones & Female Infertility). Such a delay, though, may allow one an opportunity to reduce one's toxic burden through dietary change (Hair Testing for Mercury Before Considering Pregnancy and How Long to Detox From Fish Before Pregnancy?).

During pregnancy, pollutants can be transferred directly (DDT in Umbilical Cord Blood), and after pregnancy through breastfeeding (The Wrong Way to Detox). Once our kids are contaminated, How Fast Can Children Detoxify from PCBs? The chemicals have implications for older children too: Protein, Puberty, and Pollutants.

Seafood is not the only source of toxic heavy metals. See:

Videos on primary food sources of other industrial pollutants include:

There are some things we can eat, though, to counteract some of the toxins:

-Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death,More Than an Apple a Day, and From Table to Able.

Image Credit: Kevin Krejci / Flickr

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Who Should be Careful About Curcumin?

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Following flax and wheatgrass, turmeric is the third best-selling botanical dietary supplement, racking up $12 million in sales. Currently, sales are increasing at a rate of 20%.

"Curcumin is a natural plant product extracted from the turmeric root and is used commonly as a food additive popular for its pleasant mild aroma and exotic yellow color. It is widely considered unlikely to cause side effects." However, just because something is natural doesn't mean it's not toxic. Strychnine is natural; cyanide is natural. Lead, mercury and plutonium are all elements--can't get more natural than that! But turmeric is just a plant. Surely plants can't be dangerous? Tell that to Socrates.

"In considering the validity of the widely accepted notion that complementary and alternative medicine is a safer approach to therapy, we must remind ourselves and our patients that a therapy that exerts a biologic effect is, by definition, a drug and can have toxicity." It cannot be assumed that diet-derived agents will be innocuous when administered as pharmaceutical formulations at doses likely to exceed those consumed in the diet.

Traditional Indian diets may include as much as a teaspoon of turmeric a day. Doses of turmeric that have been used in human studies range from less than just a 16th of a teaspoon a day to two tablespoons a day for over a month. On the other hand, the curcumin trials have used up to the amount found in cups of the spice, around 100 times more than what curry lovers have been eating for centuries.

Studies have yet to show overt serious side effects in the short-term. However, if we combine high dose curcumin with black pepper, resulting in a 2000% boost in bioavailability (See Boosting the Bioavailability of Curcumin), it could be like consuming the equivalent of 29 cups of turmeric a day. That kind of intake could bring peak blood levels to the range where you start seeing some significant DNA damage in vitro.

So just incorporating turmeric into your cooking may be better than taking curcumin supplements, especially during pregnancy. The only other contraindication cited in the most recent review on curcumin was the potential to trigger gallbladder pain in individuals with gallstones.

If anything, curcumin may help protect liver function and help prevent gallstones by acting as a cholecystokinetic agent, meaning that it facilitates the pumping action of the gallbladder to keep the bile from stagnating. In one study, profiled in my video, Who Shouldn't Consume Turmeric or Curcmin?, researchers gave people a small dose of curcumin, about the amount found in a quarter teaspoon of turmeric and, using ultrasound, were able to visualize the gallbladder squeezing down in response, with an average change in volume of about 29%. Optimally, though we want to squeeze it in half. So the researchers repeated the experiment with different doses. It took about 40 milligrams to get a 50% contraction, or about a third of a teaspoon of turmeric every day.

On one hand that's great--totally doable. On the other hand, that's some incredibly powerful stuff! What if you had a gallbladder obstruction? What if you had a stone blocking your bile duct? If you eat something that makes your gallbladder squeeze so much, it could cause pain. So patients with biliary tract obstruction should be careful about consuming curcumin. For everyone else, these results suggest that curcumin can effectively "induce the gallbladder to empty and thereby reduce the risk of gallstone formation and ultimately even gallbladder cancer."

Too much turmeric, though, may increase the risk of kidney stones. As I mentioned in Oxalates in Cinnamon, turmeric is high in soluble oxalates which can bind to calcium and form insoluble calcium oxalate, which is responsible for approximately 75% of all kidney stones. "The consumption of even moderate amounts of turmeric would therefore not be recommended for people with a tendency to form kidney stones." Such folks should restrict the consumption of total dietary oxalate to less than 40 to 50 mg/day, which means no more than at most a teaspoon of turmeric. Those with gout, for example, are by definition, it appears, at high risk for kidney stones, and so if their doctor wanted to treat gout inflammation with high dose turmeric, he or she might consider curcumin supplements, because to reach high levels of curcumin in turmeric form would incur too much of an oxalate load.

If we are going to take a supplement, how do we choose? The latest review recommends purchasing from Western suppliers that follow recommended Good Manufacturing Practices, which may decrease the likelihood of buying an adulterated product.

I previously discussed the role spices play in squelching inflammation and free radicals in Which Spices Fight Inflammation? and Spicing Up DNA Protection. Then out of the lab into the clinic with attempts to test the ability of turmeric extracts to treat joint inflammation with Turmeric Curcumin and Rheumatoid Arthritis and Turmeric Curcumin and Osteoarthritis.

I wish there was more science on wheatgrass. I just had that one unhelpful anecdote in my video How Much Broccoli Is Too Much? There is good science on flax though. See:

More on gallbladder health can be found in my video Cholesterol Gallstones. And those who are susceptible to kidney stones should try to alkalinize their urine by eating lots of dark green leafy vegetables. See Testing Your Diet with Pee & Purple Cabbage.

Based on this new science on turmeric (lots more to come!), I now try to include it in my family's daily diet.

-Michael Greger, M.D

PS: If you haven't yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, and From Table to Able.

Image Credit: sean dreilinger / Flickr

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How Seafood Can Impact Brain Development

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In my video Fish Intake Associated With Brain Shrinkage, I discussed evidence suggesting that mercury exposure through fish intake during pregnancy may decrease the size of the newborn's brain. However, just because fish-eating mothers may give birth to children with smaller brains doesn't necessarily mean their children will grow up with neurological defects. In the video, Mercury vs. Omega-3s for Brain Development, you can see real-time functional MRI scans of teens whose moms ate a lot of seafood when pregnant. Because these kinds of scans can measure brain activity, as opposed to just brain size, we can more accurately determine if exposure to mercury and PCBs affected these kids. You can see an MRI of what a normal brain looks like when you flash a light in someone's eyes, but the MRI is significantly different for the mercury and PCB exposed brains, suggesting toxicant related damage to the visual centers in brain. (For more on the effect of mercury on teens, see Nerves of Mercury). Fish consumption may also increase the risk of our children being born with epilepsy.

So does maternal fish consumption have an effect on how smart our kids turn out? The DHA in fish--a long chain omega 3 fatty acid--is good for brain development, but mercury is bad for brain development. So a group of researchers looked at 33 different fish species to see what the net effect of these compounds would have on children's IQ. For most fish species, they found that "the adverse effect of mercury on the IQ scores of children exceeded the beneficial effects of DHA." In fact, so much brainpower may be lost from fish consumption that the United States may actually lose $5 billion in economic productivity every year.

For example, if pregnant women ate tuna every day, the DHA would add a few IQ points. But the mercury in that very same tuna would cause so much brain damage that the overall effect of eating tuna while pregnant would be negative, wiping out an average of eight IQ points. The only two fish that were more brain-damaging than tuna were pike and swordfish.

At the other end of the spectrum, the brain boosting effect of DHA may trump the brain damaging effects of mercury in salmon by a little less than one IQ point. Unfortunately, IQ only takes into consideration the cognitive damage caused by mercury, not the adverse effects on motor function and attention and behavior deficits. We think that attention span may be particularly vulnerable to developmental mercury exposure, probably due to damage to the frontal lobes of the brain.

And the IQ study didn't take into account the relatively high levels of PCBs in salmon and the accompanying concerns about cancer risk. Sustainability concerns are another wrinkle, as farm-raised salmon are considered a "fish to avoid." While king mackerel is considered a best choice for sustainability, the mercury levels are so high as to warrant avoiding consumption--exceeding both the FDA and EPA action levels for mercury contamination. But why risk any loss in intelligence at all when pregnant women can get all the DHA they want from microalgae supplements without any of the contaminants? We can then get the brain boost without the brain damage.

More on PCBs in:

-Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, and From Table to Able.

Images thanks to Dion van Huyssteen / Flickr

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