How to Treat Dry Eye Disease Naturally with Diet

Oct 31 Dry Eyes copy.jpeg

One of the most common eye disorders, dry eye disease, causes irritation or discomfort, and can decrease functional vision, sometimes causing a dramatic deterioration in the quality of life. About five million Americans over age 50 suffer from moderate-to-severe dry eyes, and tens of millions more have mild or episodic manifestations of the disease, at a cost of more than $50 billion.

In terms of treatment, there are several drops and drugs that can help. We spend hundreds of millions of dollars on things like artificial tears, but currently there is no therapy available to actually fix the problem. If drugs don't work, doctors can try plugging up the outflow tear ducts, but that can cause complications, such as plugs migrating and eroding into the face, requiring surgical removal. Alternatively, surgeons can just cauterize or stitch up the ducts in the first place.

There has to be a better way.

What about prevention? Dry eyes can be caused by LASIK surgery, affecting about 20-40% of patients six months after the operation. With a million LASIK procedures performed annually, that's a lot of people, and sometimes the long-term symptoms can be severe and disabling.

There's a long list of drugs that can cause it, including antihistamines, decongestants, nearly all the antidepressants, anticonvulsants, antipsychotics, anti-Parkinson's drugs, beta-blockers, and hormone replacement therapy, as well as a few herbal preparations.

In the developing world, vitamin A deficiency can start out as dry eyes and then progress to becoming the leading cause of preventable childhood blindness. Vitamin A deficiency is almost never seen in the developed world, unless you do it intentionally. There was a report in the 1960s of a guy who deliberately ate a vitamin A-deficient diet, living off of bread and lime juice for five years, and his eyes developed vascularization and ulceration of the cornea, which you can see (if you dare) in my Treating Dry Eye Disease with Diet: Just Add Water? video. That was better than what happened to an unfortunate woman who was the member of a cult and tried to live off of brown rice and herbal tea: Her eyes literally melted and collapsed.

There are also a couple case reports of autistic children who refused to eat anything but French fries or menus exclusively comprised of bacon, blueberry muffins, and Kool-Aid, and became vitamin A deficient. A case in the Bronx was written up as vegan diet and vitamin A deficiency, but it had nothing to do with his vegan diet--the kid refused to eat vegetables, consuming only potato chips, puffed rice cereal with non-fortified soymilk, and juice drinks. "His parents lacked particular skill in overcoming the child's tendency to avoid fruits and vegetables."

A plant-based diet may actually be the best thing for patients with dry eye disease, those who wear contact lenses, and those who wish to maximize their tear secretions. People with dry eyes should be advised to lower protein, total fat, and cholesterol intake, and do the following:

  • increase complex carbohydrates;
  • increase vitamin A content (by eating red, orange, yellow, and dark green leafy vegetables);
  • increase zinc and folate intake (by eating whole grains, beans, and raw vegetables, especially spinach);
  • ensure sufficient vitamin B6 and potassium intake (by eating nuts, bananas, and beans);
  • ensure sufficient vitamin C intake (by eating citrus);
  • eliminate alcohol and caffeine;
  • reduce sugar and salt intake; and
  • consume six to eight glasses of water per day.

We know dehydration can cause a dry mouth, but could dehydration cause dry eyes? It may seem kind of obvious, but evidently it was never studied until recently. Is the answer to just drink more water? We know that those suffering from dry eye are comparatively dehydrated, so researchers figured that tear secretion decreases with progressive dehydration just like saliva secretion decreases and gives us a dry mouth. And indeed, as one gets more and more dehydrated, their urine concentrates and so does the tear fluid. But one can reverse that with rehydration, raising the exciting prospect that improving whole-body hydration by getting people to drink more water might bring relief for those with dry eyes. The researchers recommend eight cups of water a day for women and ten cups a day for men.


Find more on the importance of proper hydration in my How Many Glasses of Water Should We Drink a Day?, Does a Drink Of Water Make Children Smarter?, and Can Dehydration Affect Our Mood? videos.

To learn more on other topics related to eye health, check out:

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:

Original Link

How to Treat Dry Eye Disease Naturally with Diet

Oct 31 Dry Eyes copy.jpeg

One of the most common eye disorders, dry eye disease, causes irritation or discomfort, and can decrease functional vision, sometimes causing a dramatic deterioration in the quality of life. About five million Americans over age 50 suffer from moderate-to-severe dry eyes, and tens of millions more have mild or episodic manifestations of the disease, at a cost of more than $50 billion.

In terms of treatment, there are several drops and drugs that can help. We spend hundreds of millions of dollars on things like artificial tears, but currently there is no therapy available to actually fix the problem. If drugs don't work, doctors can try plugging up the outflow tear ducts, but that can cause complications, such as plugs migrating and eroding into the face, requiring surgical removal. Alternatively, surgeons can just cauterize or stitch up the ducts in the first place.

There has to be a better way.

What about prevention? Dry eyes can be caused by LASIK surgery, affecting about 20-40% of patients six months after the operation. With a million LASIK procedures performed annually, that's a lot of people, and sometimes the long-term symptoms can be severe and disabling.

There's a long list of drugs that can cause it, including antihistamines, decongestants, nearly all the antidepressants, anticonvulsants, antipsychotics, anti-Parkinson's drugs, beta-blockers, and hormone replacement therapy, as well as a few herbal preparations.

In the developing world, vitamin A deficiency can start out as dry eyes and then progress to becoming the leading cause of preventable childhood blindness. Vitamin A deficiency is almost never seen in the developed world, unless you do it intentionally. There was a report in the 1960s of a guy who deliberately ate a vitamin A-deficient diet, living off of bread and lime juice for five years, and his eyes developed vascularization and ulceration of the cornea, which you can see (if you dare) in my Treating Dry Eye Disease with Diet: Just Add Water? video. That was better than what happened to an unfortunate woman who was the member of a cult and tried to live off of brown rice and herbal tea: Her eyes literally melted and collapsed.

There are also a couple case reports of autistic children who refused to eat anything but French fries or menus exclusively comprised of bacon, blueberry muffins, and Kool-Aid, and became vitamin A deficient. A case in the Bronx was written up as vegan diet and vitamin A deficiency, but it had nothing to do with his vegan diet--the kid refused to eat vegetables, consuming only potato chips, puffed rice cereal with non-fortified soymilk, and juice drinks. "His parents lacked particular skill in overcoming the child's tendency to avoid fruits and vegetables."

A plant-based diet may actually be the best thing for patients with dry eye disease, those who wear contact lenses, and those who wish to maximize their tear secretions. People with dry eyes should be advised to lower protein, total fat, and cholesterol intake, and do the following:

  • increase complex carbohydrates;
  • increase vitamin A content (by eating red, orange, yellow, and dark green leafy vegetables);
  • increase zinc and folate intake (by eating whole grains, beans, and raw vegetables, especially spinach);
  • ensure sufficient vitamin B6 and potassium intake (by eating nuts, bananas, and beans);
  • ensure sufficient vitamin C intake (by eating citrus);
  • eliminate alcohol and caffeine;
  • reduce sugar and salt intake; and
  • consume six to eight glasses of water per day.

We know dehydration can cause a dry mouth, but could dehydration cause dry eyes? It may seem kind of obvious, but evidently it was never studied until recently. Is the answer to just drink more water? We know that those suffering from dry eye are comparatively dehydrated, so researchers figured that tear secretion decreases with progressive dehydration just like saliva secretion decreases and gives us a dry mouth. And indeed, as one gets more and more dehydrated, their urine concentrates and so does the tear fluid. But one can reverse that with rehydration, raising the exciting prospect that improving whole-body hydration by getting people to drink more water might bring relief for those with dry eyes. The researchers recommend eight cups of water a day for women and ten cups a day for men.


Find more on the importance of proper hydration in my How Many Glasses of Water Should We Drink a Day?, Does a Drink Of Water Make Children Smarter?, and Can Dehydration Affect Our Mood? videos.

To learn more on other topics related to eye health, check out:

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:

Original Link

What Not to Add to White Rice, Potatoes, or Pasta

What Not to Add to White Rice, Potatoes, or Pasta.jpeg

Rice currently feeds almost half the human population, making it the single most important staple food in the world, but a meta-analysis of seven cohort studies following 350,000 people for up to 20 years found that higher consumption of white rice was associated with a significantly increased risk of type 2 diabetes, especially in Asian populations. They estimated each serving per day of white rice was associated with an 11% increase in risk of diabetes. This could explain why China has almost the same diabetes rates as we do.

Diabetes rates in China are at about 10%; we're at about 11%, despite seven times less obesity in China. Japan has eight times less obesity than we do, yet may have a higher incidence of newly diagnosed diabetes cases than we do--nine per a thousand compared to our eight. They're skinnier and still may have more diabetes. Maybe it's because of all the white rice they eat.

Eating whole fruit is associated with lower risk of diabetes, whereas eating fruit processed into juice may not just be neutral, but actually increases diabetes risk. In the same way, eating whole grains, like whole wheat bread or brown rice is associated with lower risk of diabetes, whereas eating white rice, a processed grain, may not just be neutral, but actually increase diabetes risk.

White rice consumption does not appear to be associated with increased risk of heart attack or stroke, though, which is a relief after an earlier study in China suggested a connection with stroke. But do we want to eat a food that's just neutral regarding some of our leading causes of death, when we can eat whole foods that are associated with lower risk of diabetes, heart attack, stroke, and weight gain?

If the modern diabetes epidemic in China and Japan has been linked to white rice consumption, how can we reconcile that with low diabetes rates just a few decades ago when they ate even more rice? If you look at the Cornell-Oxford-China Project, rural plant-based diets centered around rice were associated with relatively low risk of the so-called diseases of affluence, which includes diabetes. Maybe Asians just genetically don't get the same blood sugar spike when they eat white rice? This is not the case; if anything people of Chinese ethnicity get higher blood sugar spikes.

The rise in these diseases of affluence in China over the last half century has been blamed in part on the tripling of the consumption of animal source foods. The upsurge in diabetes has been most dramatic, and it's mostly just happened over the last decade. That crazy 9.7% diabetes prevalence figure that rivals ours is new--they appeared to have one of the lowest diabetes rates in the world in the year 2000.

So what happened to their diets in the last 20 years or so? Oil consumption went up 20%, pork consumption went up 40%, and rice consumption dropped about 30%. As diabetes rates were skyrocketing, rice consumption was going down, so maybe it's the animal products and junk food that are the problem. Yes, brown rice is better than white rice, but to stop the mounting Asian epidemic, maybe we should focus on removing the cause--the toxic Western diet. That would be consistent with data showing animal protein and fat consumption associated with increased diabetes risk.

But that doesn't explain why the biggest recent studies in Japan and China associate white rice intake with diabetes. One possibility is that animal protein is making the rice worse. If you feed people mashed white potatoes, a high glycemic food like white rice, you can see in my video If White Rice is Linked to Diabetes, What About China? the level of insulin your pancreas has to pump out to keep your blood sugars in check. But what if you added some tuna fish? Tuna doesn't have any carbs, sugar, or starch so it shouldn't make a difference. Or maybe it would even lower the mashed potato spike by lowering the glycemic load of the whole meal? Instead you get twice the insulin spike. This also happens with white flour spaghetti versus white flour spaghetti with meat. The addition of animal protein makes the pancreas work twice as hard.

You can do it with straight sugar water too. If you do a glucose challenge test to test for diabetes, where you drink a certain amount of sugar and add some meat, you get a much bigger spike than without meat. And the more meat you add, the worse it gets. Just adding a little meat to carbs doesn't seem to do much, but once you get up to around a third of a chicken breast's worth, you can elicit a significantly increased surge of insulin. This may help explain why those eating plant-based have such low diabetes rates, because animal protein can markedly potentiate the insulin secretion triggered by carbohydrate ingestion.

The protein exacerbation of the effect of refined carbs could help explain the remarkable results achieved by Dr. Kempner with a don't-try-this-at-home diet composed of mostly white rice and sugar. See my video, Kempner Rice Diet: Whipping Us Into Shape.

Refined grains may also not be good for our blood pressure (see Whole Grains May Work As Well As Drugs).

What should we be eating to best decrease our risk of diabetes? See:

And check out my summary video, How Not to Die from Diabetes.

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

What Not to Add to White Rice, Potatoes, or Pasta

What Not to Add to White Rice, Potatoes, or Pasta.jpeg

Rice currently feeds almost half the human population, making it the single most important staple food in the world, but a meta-analysis of seven cohort studies following 350,000 people for up to 20 years found that higher consumption of white rice was associated with a significantly increased risk of type 2 diabetes, especially in Asian populations. They estimated each serving per day of white rice was associated with an 11% increase in risk of diabetes. This could explain why China has almost the same diabetes rates as we do.

Diabetes rates in China are at about 10%; we're at about 11%, despite seven times less obesity in China. Japan has eight times less obesity than we do, yet may have a higher incidence of newly diagnosed diabetes cases than we do--nine per a thousand compared to our eight. They're skinnier and still may have more diabetes. Maybe it's because of all the white rice they eat.

Eating whole fruit is associated with lower risk of diabetes, whereas eating fruit processed into juice may not just be neutral, but actually increases diabetes risk. In the same way, eating whole grains, like whole wheat bread or brown rice is associated with lower risk of diabetes, whereas eating white rice, a processed grain, may not just be neutral, but actually increase diabetes risk.

White rice consumption does not appear to be associated with increased risk of heart attack or stroke, though, which is a relief after an earlier study in China suggested a connection with stroke. But do we want to eat a food that's just neutral regarding some of our leading causes of death, when we can eat whole foods that are associated with lower risk of diabetes, heart attack, stroke, and weight gain?

If the modern diabetes epidemic in China and Japan has been linked to white rice consumption, how can we reconcile that with low diabetes rates just a few decades ago when they ate even more rice? If you look at the Cornell-Oxford-China Project, rural plant-based diets centered around rice were associated with relatively low risk of the so-called diseases of affluence, which includes diabetes. Maybe Asians just genetically don't get the same blood sugar spike when they eat white rice? This is not the case; if anything people of Chinese ethnicity get higher blood sugar spikes.

The rise in these diseases of affluence in China over the last half century has been blamed in part on the tripling of the consumption of animal source foods. The upsurge in diabetes has been most dramatic, and it's mostly just happened over the last decade. That crazy 9.7% diabetes prevalence figure that rivals ours is new--they appeared to have one of the lowest diabetes rates in the world in the year 2000.

So what happened to their diets in the last 20 years or so? Oil consumption went up 20%, pork consumption went up 40%, and rice consumption dropped about 30%. As diabetes rates were skyrocketing, rice consumption was going down, so maybe it's the animal products and junk food that are the problem. Yes, brown rice is better than white rice, but to stop the mounting Asian epidemic, maybe we should focus on removing the cause--the toxic Western diet. That would be consistent with data showing animal protein and fat consumption associated with increased diabetes risk.

But that doesn't explain why the biggest recent studies in Japan and China associate white rice intake with diabetes. One possibility is that animal protein is making the rice worse. If you feed people mashed white potatoes, a high glycemic food like white rice, you can see in my video If White Rice is Linked to Diabetes, What About China? the level of insulin your pancreas has to pump out to keep your blood sugars in check. But what if you added some tuna fish? Tuna doesn't have any carbs, sugar, or starch so it shouldn't make a difference. Or maybe it would even lower the mashed potato spike by lowering the glycemic load of the whole meal? Instead you get twice the insulin spike. This also happens with white flour spaghetti versus white flour spaghetti with meat. The addition of animal protein makes the pancreas work twice as hard.

You can do it with straight sugar water too. If you do a glucose challenge test to test for diabetes, where you drink a certain amount of sugar and add some meat, you get a much bigger spike than without meat. And the more meat you add, the worse it gets. Just adding a little meat to carbs doesn't seem to do much, but once you get up to around a third of a chicken breast's worth, you can elicit a significantly increased surge of insulin. This may help explain why those eating plant-based have such low diabetes rates, because animal protein can markedly potentiate the insulin secretion triggered by carbohydrate ingestion.

The protein exacerbation of the effect of refined carbs could help explain the remarkable results achieved by Dr. Kempner with a don't-try-this-at-home diet composed of mostly white rice and sugar. See my video, Kempner Rice Diet: Whipping Us Into Shape.

Refined grains may also not be good for our blood pressure (see Whole Grains May Work As Well As Drugs).

What should we be eating to best decrease our risk of diabetes? See:

And check out my summary video, How Not to Die from Diabetes.

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

What About All the Sugar in Fruit?

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If the fructose in sugar and high fructose corn syrup has been considered "alcohol without the buzz" in terms of the potential to inflict liver damage, what about the source of natural fructose, fruit?

If you compare the effects of a diet restricting fructose from both added sugars and fruit to one just restricting fructose from added sugars, the diet that kept the fruit did better. People lost more weight with the extra fruit present than if all fructose was restricted. Only industrial, not fruit fructose intake, was associated with declining liver function and high blood pressure. Fructose from added sugars was associated with hypertension; fructose from natural fruits is not.

If we have people drink a glass of water with three tablespoons of table sugar in it, which is like a can of soda, they get a big spike in blood sugar within the first hour (as you can see in my video If Fructose is Bad, What About Fruit?). Our body freaks out and releases so much insulin we actually overshoot, and by the second hour we're relatively hypoglycemic, dropping our blood sugar below where they were when we started out fasting. In response, our body dumps fat into our blood stream as if we're starving, because our blood sugars just dropped so low so suddenly.

What if you eat blended berries in addition to the sugar? They have sugars of their own in them, in fact an additional tablespoon of sugar worth, so the blood sugar spike should be worse, right?

Not only is there no additional blood sugar spike, there was no hypoglycemic dip afterwards. Blood sugar just went up and down without that overshoot and without the surge of fat into the blood.

This difference may be attributed to the semisolid consistency of the berry meals, which may have decreased the rate of stomach emptying compared with just guzzling sugar water. In addition, the soluble fiber in the berries has a gelling effect in our intestines that slows the release of sugars. To test to see if it was the fiber, researchers repeated the experiment with berry juice that had all the sugar but none of the fiber. A clear difference was observed early on in the blood sugar insulin responses. At the 15-minute mark, the blood sugar spike was significantly reduced by the berry meals, but not by the juices, but the rest of the beneficial responses were almost the same between the juice and the whole fruit, suggesting that fiber may just be part of it. It turns out there are fruit phytonutrients that inhibit the transportation of sugars through the intestinal wall into our blood stream. Phytonutrients in foods like apples and strawberries can block some of the uptake of sugars by the cells lining our intestines.

Adding berries can actually blunt the insulin spike from high glycemic foods. For example, white bread creates a big insulin spike within two hours after eating it. Eat that same white bread with some berries, though, and we're able to blunt the spike. So, even though we've effectively added more sugars in the form of berries, there's less of an insulin spike, which has a variety of potential short and long-term benefits. So if you're going to make pancakes, make sure they're blueberry pancakes.

Surprised about the juice results? Me too! More on juice:

A few videos I have on industrial sugars:

How else can we blunt the glycemic spike?

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--2013: Uprooting the Leading Causes of Death, More Than an Apple a Day, 2014: From Table to Able: Combating Disabling Diseases with Food, 2015: Food as Medicine: Preventing and Treating the Most Dreaded Diseases with Diet, and my latest, 2016: How Not To Die: The Role of Diet in Preventing, Arresting, and Reversing Our Top 15 Killers.

Original Link

Why Smoothies are Better Than Juicing

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Studies such as a recent Harvard School of Public Health investigation found that the consumption of whole fruits is associated with a significantly lower risk of type 2 diabetes, whereas fruit juice consumption is associated with a higher risk, highlighting the dramatic difference between eating whole fruits and drinking fruit juice. Cholesterol serves as another example. If we eat apples, our cholesterol drops. On the other hand, if we drink apple juice, our cholesterol may actually go up a little. Leaving just a little of the fiber behind--as in cloudy apple juice--was found to add back in some of the benefit.

We used to think of fiber as just a bulking agent that helps with bowel regularity. We now know fiber is digestible by our gut bacteria, which make short chain fatty acids (SCFAs) out of it. SCFAs have a number of health promoting effects, such as inhibiting the growth of bad bacteria and increasing mineral absorption. For example, experimentally infused into the rectum of the human body, SCFAs can stimulate calcium absorption, so much so that we can improve the bone mineral density of teenagers just by giving them the fiber naturally found in foods like onions, asparagus, and bananas.

Our good bacteria also uses fiber to maintain normal bowel structure and function, preventing or alleviating diarrhea, stimulating colonic blood flow up to five-fold, and increasing fluid and electrolyte uptake. The major fuel for the cells that line our colon is butyrate, which our good bacteria make from fiber. We feed them, and they feed us right back.

If the only difference between fruit and fruit juice is fiber, why can't the juice industry just add some fiber back to the juice? The reason is because we remove a lot more than fiber when we juice fruits and vegetables. We also lose all the nutrients that are bound to the fiber.

In the 1980's, a study (highlighted in my video, Juicing Removes More Than Just Fiber) found a discrepancy in the amount of fiber in carob using two different methods. A gap of 21.5 percent was identified not as fiber but as nonextractable polyphenols, a class of phytonutrients thought to have an array of health-promoting effects. Some of the effects associated with the intake of dietary fiber in plants may actually be due to the presence of these polyphenols.

Nonextractable polyphenols, usually ignored, are the major part of dietary polyphenols. Most polyphenol phytonutrients in plants are stuck to the fiber. These so-called missing polyphenols make it down to our colon, are liberated by our friendly flora and can then get absorbed into our system. The phytonutrients in fruit and vegetable juice may just be the tip of the iceberg.

For those that like drinking their fruits and vegetables, these findings suggest that smoothies may be preferable. I can imagine people who eat really healthy thinking they get so much fiber from their regular diet that they need not concern themselves with the loss from juicing. But we may be losing more than we think.

For those that like drinking their fruits and vegetables, this suggests smoothies are preferable. I can imagine people who eat really healthy thinking they get so much fiber from their regular diet that they need not concern themselves with the loss from juicing, but they may be losing more than they think.

Why are polyphenol phytonutrients important? See, for example, my video How to Slow Brain Aging by Two Years

Not that fiber isn't important in its own right. Check out:

For more on smoothies, check out:

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: Craig Sunter / Flickr

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

Slowing Cognitive Decline with Berries

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A plant-based diet is thought to have played a significant role in human evolution and the consumption of whole plant foods and even just extracts have repeatedly been associated with a decreased risk of aging related diseases. And by healthy aging I'm not talking preventing wrinkles, what about protecting our brain? "Two of the most dreaded consequences of dementia with aging are problems moving around and difficulty remembering things. Dementia robs older adults of their independence, control, and identity."

Fruits and vegetables help reduce the risk of other chronic diseases, so might they work for brain diseases as well?

There has been a proliferation of recent interest in plant polyphenols as agents in the treatment of dementia. There are 4,000 different kinds of polyphenols found ubiquitously in foods of plant origin, but berries are packed with them, possessing powerful antioxidant and anti-inflammatory properties. There's a subset of polyphenols called anthocyanidins, which are found in blue and purple pigmented fruits and berries. These polyphenols are uniquely and specifically capable of "both crossing the blood-brain barrier and localizing in brain regions involved in learning and memory." And that's precisely where we need them.

The brain takes up less than 2% of body weight but may burn up to 50% of the body's fuel, creating a potential firestorm of free radicals. Maybe these brain-seeking phytonutrients in berries could fight oxidation and inflammation, and even increase blood flow? This raised a thought-provoking idea. Maybe a "nutritional intervention with blueberries may be effective in forestalling or even reversing the neurological changes associated with aging?" It would be a decade before the first human trial was conducted, but it worked! "Blueberry supplementation improves memory in older adults," suggesting that "consistent supplementation with blueberries may offer an approach to forestall or mitigate brain degeneration with age."

What other blue or purple foods can we try? Concord grape juice was also tested and had a similar benefit, suggesting that supplementation with purple grape juice may enhance cognitive function for older adults with early memory decline. Why use juice and not whole concord grapes? Because then you couldn't design a placebo that looked and tasted exactly the same to rule out the very real and powerful placebo effect. And also because the study was funded by the Welch's grape juice company.

This effect was confirmed in a follow-up study, showing for the first time an increase in neural activation in parts of the brain associated with memory using functional MRI scans. But this brain scan study was tiny: just four people in each group. And same problem in the blueberry study: it had only nine people in it.

Why haven't large population-based studies been done? Because we haven't had good databases on where these phytonutrients are found. We know how much vitamin C is in a blueberry, but not how much anthocyanidin--until now. The Harvard Nurses' Health Study, highlighted in my video, How to Slow Brain Aging by Two Years, followed the cognitive function of more than 16,000 women for years, and found that "long-term consumption of berries was related to significantly slower rates of cognitive decline, even after careful consideration of confounding socioeconomic status" (that is, even after taking into account the fact that rich people eat more berries). The Harvard Nurses' Health Study was the first population-based evidence that greater intakes of blueberries and strawberries were highly associated with slower rates of cognitive decline, and not just by a little bit. "The magnitude of associations were equivalent to the cognitive differences that one might observe in women up to two and a half years apart in age." In other words, women with higher intake of berries appeared to have delayed cognitive aging by as much as two and a half years.

Why shouldn't we just take some anthocyanidin supplement? Because there hasn't been a single study that found any kind of cognitive benefit by just giving single phytonutrients. In fact, the opposite is true. "Whole blueberries appear to be more effective than individual components, showing that the whole is greater than the sum of its parts." These findings have potentially substantial public health implications, as increasing berry intake represents a fairly simple dietary modification to test in older adults for maintaining our brain function.

What other ways could we improve our memory and cognitive function?

What other near-miraculous properties of berries are there?

I add them to my morning smoothie: A Better Breakfast.

-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: Angelo Desantis / Flickr

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Foods for Glaucoma

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Glaucoma is the second leading cause of legal blindness in white women, and the number one cause of blindness in African-American women. In a study I profile in the video Greens vs. Glaucoma, researchers chose a population of African-American women to study the effects of fruit and vegetable consumption on glaucoma risk because they were specifically interested in studying the effect of foods with the highest concentration of those eye-protecting phytonutrients like zeaxanthin. Zeaxanthin is found primarily in plants such as kale and collard greens. (It is also found in eggs--find out how much in Egg Industry Blind Spot). However, we'd be lucky if we could find one in ten white people eating even a single serving of these dark green leafy vegetables a month, whereas nearly nine out of ten African-American women in the study consumed this amount.

What did the researchers find? Well, as I've stressed over the years, all fruits and vegetables are not the same (see for example, How to Reach the Antioxidant "RDA"). Whether the participants hardly ever ate bananas or had one or more every day didn't seem to matter much in terms of the risk of glaucoma. However, eating only a couple oranges every week was associated with dramatically lower risk. Orange juice was not associated with a lower risk, though, even if drunk every day. A similar finding was found for peaches: fresh peaches seemed to help, but canned peaches didn't.

Similarly the intake of vegetables in general as a catch-all term didn't seem to matter. For example, whether subjects ate a green salad twice a week, once a week, or zero times a week didn't seem to matter when it came to reducing glaucoma risk, but most people's salads are pretty pitiful. It was a different story for kale and collard greens: just two or three servings a month was associated with half the risk of glaucoma compared to once a month or less.

It may be especially important for white people to consume kale and collard greens. The lighter our eye color, the more greens we need to eat. Blue eyes let 100 times more light through, so people with blue or gray eyes appear significantly more vulnerable to damage compared to brown or black. Green and hazel fall somewhere in the middle.

This is interesting: carrots appeared to be less protective in black women compared to white women. They suggest it could be a difference in food preparation methods. Perhaps the African-American subjects tended to eat carrots raw, limiting the absorption of certain nutrients, while they chopped and prepared their collard greens with oil, making the nutrients more bioavailable because the absorption of carotenoid phytonutrients depends on the presence of fat. This is why I encourage people to eat nuts or seeds with the greens--such as a little tahini sauce or something.

Why not just take a zeaxanthin pill? We don't know what exactly it is in these wonderful foods that's working their wonders, so it's probably better to just eat our greens rather than supplements. In fact, people that take calcium or iron supplements may even be doubling, quadrupling, or septupling their odds of glaucoma. It's better to get most of our nutrients from produce, not pills.

I wish there were more studies on under-represented populations. I've covered a few, such as Preventing Breast Cancer By Any Greens Necessary, but I am constantly on the lookout for more.

My other videos on glaucoma include Prevent Glaucoma and See 27 Miles Farther and Dietary Treatment of Glaucoma. For more on eye health check out my video, Dietary Prevention of Age-Related Macular Degeneration.

-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: bruno garciact / Flickr

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The Reason We Need More Antioxidants

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Glucose is the primary fuel of the human body. We consume glucose and breathe in oxygen to make the energy needed to power our bodies. Plants then take the water and carbon dioxide we breathe out to make oxygen and organic compounds like glucose--and the circle of life continues. The word carbohydrate means, basically, hydrated carbon, which is what plants use to make carbs and all that's left after we burn them for energy in our muscles and brain.

This process of oxidizing glucose to make energy is messy, though, and generates free radicals. Chugging sugar water increases the level of oxidation in our bloodstreams over the next few hours as our bodies metabolize the glucose. (Digestion isn't the only physiological source of free radicals--exercise is too. See Preventing Exercise-Induced Oxidative Stress With Watercress). Why would we evolve to have a negative reaction to our primary fuel? Because over the millions of years we evolved, there was no such thing as sugar water--all sugars and starches came pre-packaged with protective compounds: antioxidants. In nature, sugar always comes with phytonutrients.

If we drink the same amount of sugar in the form of orange juice, we don't get that spike in oxidation, because the sugar in fruit comes prepackaged with antioxidants. We can't just drink vitamin C enriched sugar water either, because it's not the vitamin C in the OJ but the citrus phytonutrients like hesperetin and naringenin that beat back the oxidation. And it's always better to eat the whole fruit than drink the juice (See Best Fruit Juice and Apple Juice May Be Worse Than Sugar Water). If those citrus phytonutrients sounded familiar to you, it's because I mentioned them before in videos like Keeping Your Hands Warm With Citrus and Reducing Muscle Fatigue With Citrus.

If we don't eat phytonutrient-rich plant foods with each meal, then for hours after we eat, our bodies are tipped out of balance into a pro-oxidative state, which can set us up for oxidant stress diseases. That's why we need to ideally eat antioxidant rich foods with every meal.

In the video, Minimum "Recommended Daily Allowance" of Antioxidants, we can see the levels of oxidized fat in our blood one, two, and three hours after sugar water ingestion, and the corresponding drop in vitamin E levels in our blood as our body's antioxidant stores are being used up. If we don't eat phytonutrient-rich foods with our meals, our body has to dip into its backup supply of antioxidants. We can't get away with that for long. So while ideally we should stuff our faces with as many phytonutrient-rich foods as we can.

In the very least we should eat enough antioxidants to counter the oxidation of digestion. We don't want to slide backwards every day and end up with less antioxidants in our bodies than we woke up with.

A chart in the video, Minimum "Recommended Daily Allowance" of Antioxidants, shows the amount of antioxidants we need every day, depending on how much we eat, just to counter the oxidation of digestion. Men in the U.S. average about 2500 calories a day and so should be getting at least 11,000 antioxidant units a day. Women eat about 1800 calories and so should get at least 8,000 units just to stay solvent. However, the average American doesn't even get half the minimum-no wonder oxidant stress related diseases abound. We're getting so few antioxidants in our diet that we can't even keep up with the free radicals created by merely digesting our meals. We are a nation in chronic oxidative debt.

Developed societies eat a lot of food but not enough plants, which could result in exaggerated and prolonged metabolic, oxidative, and immune imbalance. This presents opportunity for biological insult that over time could supersede our defense and repair systems, and manifest in cellular dysfunction, disease, and ultimately death.

Is there a refined sweetener that doesn't cause free radical formation? Yes: Erythritol May Be a Sweet Antioxidant.

What's the best way of reaching our daily minimum of 8,000-11,000 antioxidant units a day? That's covered in my video How to Reach the Antioxidant "RDA".

Background on the role free radicals play in aging and disease can be found in my video Mitochondrial Theory of Aging. Antioxidant-rich diets can even change gene expression: Plant-Based Diets and Cellular Stress Defenses.

-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: Benson Kua / Flickr

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