Can You Eat Too Much Fruit?

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In my video If Fructose is Bad, What About Fruit?, I explored how adding berries to our meals can actually blunt the detrimental effects of high glycemic foods, but how many berries? The purpose of one study out of Finland was to determine the minimum level of blueberry consumption at which a consumer may realistically expect to receive antioxidant benefits after eating blueberries with a sugary breakfast cereal. If we eat a bowl of corn flakes with no berries, within two hours, so many free radicals are created that it puts us into oxidative debt. The antioxidant power of our bloodstream drops below where we started from before breakfast, as the antioxidants in our bodies get used up dealing with such a crappy breakfast. As you can see in How Much Fruit is Too Much? video, a quarter cup of blueberries didn't seem to help much, but a half cup of blueberries did.

What about fruit for diabetics? Most guidelines recommend eating a diet with a high intake of fiber-rich food, including fruit, because they're so healthy--antioxidants, anti-inflammatory, improving artery function, and reducing cancer risk. However, some health professionals have concerns about the sugar content of fruit and therefore recommend restricting the fruit intake. So let's put it to the test! In a study from Denmark, diabetics were randomized into two groups: one told to eat at least two pieces of fruit a day, and the other told at most, two fruits a day. The reduce fruit group indeed reduce their fruit consumption, but it had no effect on the control of their diabetes or weight, and so, the researchers concluded, the intake of fruit should not be restricted in patients with type 2 diabetes. An emerging literature has shown that low-dose fructose may actually benefit blood sugar control. Having a piece of fruit with each meal would be expected to lower, not raise the blood sugar response.

The threshold for toxicity of fructose may be around 50 grams. The problem is that's the current average adult fructose consumption. So, the levels of half of all adults are likely above the threshold for fructose toxicity, and adolescents currently average 75. Is that limit for added sugars or for all fructose? If we don't want more than 50 and there's about ten in a piece of fruit, should we not eat more than five fruit a day? Quoting from the Harvard Health Letter, "the nutritional problems of fructose and sugar come when they are added to foods. Fruit, on the other hand, is beneficial in almost any amount." What do they mean almost? Can we eat ten fruit a day? How about twenty fruit a day?

It's actually been put to the test.

Seventeen people were made to eat 20 servings a day of fruit. Despite the extraordinarily high fructose content of this diet, presumably about 200 g/d--eight cans of soda worth, the investigators reported no adverse effects (and possible benefit actually) for body weight, blood pressure, and insulin and lipid levels after three to six months. More recently, Jenkins and colleagues put people on about a 20 servings of fruit a day diet for a few weeks and found no adverse effects on weight or blood pressure or triglycerides, and an astounding 38 point drop in LDL cholesterol.

There was one side effect, though. Given the 44 servings of vegetables they had on top of all that fruit, they recorded the largest bowl movements apparently ever documented in a dietary intervention.


Cutting down on sugary foods may be easier said than done (see Are Sugary Foods Addictive?) but it's worth it. For more on the dangers of high levels of fructose in added sugars, see How Much Added Sugar Is Too Much?.

What's that about being in oxidative debt? See my three part series on how to pull yourself out of the red:

Ironically, fat may be more of a problem when it comes to diabetes than sugar, 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:

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

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Can You Eat Too Much Fruit?

Can You Eat Too Much Fruit?.jpeg

In my video If Fructose is Bad, What About Fruit?, I explored how adding berries to our meals can actually blunt the detrimental effects of high glycemic foods, but how many berries? The purpose of one study out of Finland was to determine the minimum level of blueberry consumption at which a consumer may realistically expect to receive antioxidant benefits after eating blueberries with a sugary breakfast cereal. If we eat a bowl of corn flakes with no berries, within two hours, so many free radicals are created that it puts us into oxidative debt. The antioxidant power of our bloodstream drops below where we started from before breakfast, as the antioxidants in our bodies get used up dealing with such a crappy breakfast. As you can see in How Much Fruit is Too Much? video, a quarter cup of blueberries didn't seem to help much, but a half cup of blueberries did.

What about fruit for diabetics? Most guidelines recommend eating a diet with a high intake of fiber-rich food, including fruit, because they're so healthy--antioxidants, anti-inflammatory, improving artery function, and reducing cancer risk. However, some health professionals have concerns about the sugar content of fruit and therefore recommend restricting the fruit intake. So let's put it to the test! In a study from Denmark, diabetics were randomized into two groups: one told to eat at least two pieces of fruit a day, and the other told at most, two fruits a day. The reduce fruit group indeed reduce their fruit consumption, but it had no effect on the control of their diabetes or weight, and so, the researchers concluded, the intake of fruit should not be restricted in patients with type 2 diabetes. An emerging literature has shown that low-dose fructose may actually benefit blood sugar control. Having a piece of fruit with each meal would be expected to lower, not raise the blood sugar response.

The threshold for toxicity of fructose may be around 50 grams. The problem is that's the current average adult fructose consumption. So, the levels of half of all adults are likely above the threshold for fructose toxicity, and adolescents currently average 75. Is that limit for added sugars or for all fructose? If we don't want more than 50 and there's about ten in a piece of fruit, should we not eat more than five fruit a day? Quoting from the Harvard Health Letter, "the nutritional problems of fructose and sugar come when they are added to foods. Fruit, on the other hand, is beneficial in almost any amount." What do they mean almost? Can we eat ten fruit a day? How about twenty fruit a day?

It's actually been put to the test.

Seventeen people were made to eat 20 servings a day of fruit. Despite the extraordinarily high fructose content of this diet, presumably about 200 g/d--eight cans of soda worth, the investigators reported no adverse effects (and possible benefit actually) for body weight, blood pressure, and insulin and lipid levels after three to six months. More recently, Jenkins and colleagues put people on about a 20 servings of fruit a day diet for a few weeks and found no adverse effects on weight or blood pressure or triglycerides, and an astounding 38 point drop in LDL cholesterol.

There was one side effect, though. Given the 44 servings of vegetables they had on top of all that fruit, they recorded the largest bowl movements apparently ever documented in a dietary intervention.


Cutting down on sugary foods may be easier said than done (see Are Sugary Foods Addictive?) but it's worth it. For more on the dangers of high levels of fructose in added sugars, see How Much Added Sugar Is Too Much?.

What's that about being in oxidative debt? See my three part series on how to pull yourself out of the red:

Ironically, fat may be more of a problem when it comes to diabetes than sugar, 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:

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.

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How Much Added Sugar is Too Much?

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In 1776, at the time of the American Revolution, Americans consumed about four pounds of sugar per person each year. By 1850, this had risen to 20 pounds, and by 1994 to 120 pounds. Now we're closer to 160 (See How Much Added Sugar is Too Much?). Half of table sugar is fructose, taking up about 10 percent of our diet. This is not from eating apples, but rather the fact that we're each guzzling the equivalent of 16-ounce soft drink every day; that's about 50 gallons a year.

Even researchers paid by the likes of the Dr. Pepper Snapple Group and The Coca Cola Company acknowledge that sugar is empty calories, containing "no essential micronutrients, and therefore if we're trying to reduce calorie intake, reducing sugar consumption is obviously the place to start." Concern has been raised, though, that sugar calories may be worst than just empty.

A growing body of scientific evidence suggests that "the fructose added to foods and beverages in the form of table sugar and high fructose corn syrup in large enough amounts can trigger processes that lead to liver toxicity and other chronic diseases."

Fructose hones in like a laser beam on the liver, and like alcohol, fructose can increase the fat in the liver. The increase in non-alcoholic fatty liver disease is one of the most remarkable medical developments over the past three decades--the emergence of fatty liver inflammation as a public health problem here and around the globe.

These may not be messages that the sugar industry or beverage makers want to hear. In response, the director-general of the industry front group, the World Sugar Research Organization, replied, "Overconsumption of anything is harmful, including water and air." Yes, he compared the overconsumption of sugar to breathing too much.

Under American Heart Association's new sugar guidelines, most American women should consume no more than 100 calories per day from added sugars, and most American men should eat or drink no more than 150. That means one can of soda could take us over the top for the day. The new draft guidelines from the World Health Organization suggests we could benefit from restricting added sugars to under 5 percent of calories. That's about six spoonfuls of added sugar. I don't know why they don't just recommend zero as optimal, but you can get a sense of how radical their proposal is given that we consume an average of 12-18 spoonfuls a day right now.

This underscores why a whole foods, plant-based diet is preferable to a plant-based diet that includes processed junk.

I've touched on the harm of refined sugars before in:

For healthful alternatives in baking, see The Healthiest Sweetener, and for beverages, Erythritol May Be a Sweet Antioxidant.

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: Adam Engelhart / Flickr

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Anti-Cancer Nutrient Synergy in Cranberries

 

 

 

 

 

 

 

 

Anti-Cancer Nutrient Synergy in Cranberries

In research I profiled in my video Which Fruit Fights Cancer Better?, cranberries were found to suppress the growth of human liver cancer cells in vitro. Other studies have found similar effects against human breast, colon, brain tumor, oral, and ovarian cancer cells. In my 4-min video Cranberries versus Cancer I profile the latest looking at prostate cancer cell growth.

The United States has the highest rate of prostate cancer in the world, so let’s try a native American fruit! Researchers started out with about 50,000 human prostate cancer cells in a petri dish and if you do nothing, within a day you’re closer to 100,000, then 200,000 and then nearly 400,000 within 72 hours. But by adding just a tiny amount of cranberries, that exponential cancer growth can be blocked.

The reason they tested such tiny concentrations is that we only absorb a small fraction of the cranberry phytonutrients we eat into our bloodstream. Still, cranberries are cheap. If drug companies and supplement manufacturers are going to capitalize on this they needed to find cranberry’s active ingredient.

In my video Cranberries versus Cancer I show a graph with some of the various phytonutrients in cranberries. Different fractions were tested against various types of cancer to find the magic bullet. Various fractions of phytonutrients inhibited colon cancer cell proliferation about 15 percent, but nothing compared to the total extract of the whole fruit. There seems to be additive or synergistic anti-proliferative effects resulting from the combination of the various components compared to individual purified phytochemicals. So it’s always better to eat the whole fruit.

How do you do that with cranberries, though? Although five percent of cranberries are sold fresh, the vast majority are consumed as processed products. To get the same amount of anthocyanin phytonutrients in a cup of fresh or frozen cranberries, you’d have to drink 16 cups of cranberry juice cocktail, eat seven cups of dried cranberries, or 26 cans of cranberry sauce!

The problem is that raw cranberries are so tart that folks may opt for the 7 cups of dried. In a taste test survey, consumers said they wouldn’t mind eating dried cranberries every day, but the preference for raw cranberries sloped down toward maybe once a year. The problem is dried cranberries tend to come sweetened. Raw cranberries don’t affect your blood sugar, but sweetened dried cranberries do—even the low sugar varieties.

What about cranberry “juice”? Cranberry cocktail is usually only about a quarter cranberry juice. The ruby red phytonutrients in cranberries and pure cranberry juice are powerful antioxidants, increasing the antioxidant capacity of our bloodstream within hours of consumption. But the high fructose corn syrup acts as a pro-oxidant, even with added vitamin C, canceling out some of the cranberry benefit. So how do you get the upsides without the down? Check out my Pink Juice with Green Foam video, where I offer a recipe for making no added sugar whole fruit cranberry cocktail.

And for another reason to avoid high fructose corn syrup: Mercury in Corn Syrup?

More on nutrient synergy in:

Suppressing cancer growth in a petri dish is nice, but what about within the human body? Check out my videos Strawberries versus Esophageal Cancer and Black Raspberries versus Oral Cancer. 

-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 and More Than an Apple a Day.

Image credit: Muffet / Flickr

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