Doctor's Note

For more on sugar and high-fructose corn syrup, check out these videos:
Flesh and Fructose
How Much Added Sugar Is Too Much?
If Fructose is Bad, What About Fruit?

And check out my other videos on processed foods

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  • Michael Greger M.D.

    Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. And check out the other videos on processed foods. Also, there are 1,449 other subjects covered in the rest of my videos–please feel free to explore them as well!

  • Dave Stone

    Hi Doc G, might be worth mentioning here as well that the ~50/50 ratio of glucose/fructose is the norm in nature. Most fruits and sweet vegetables contain approximately this ratio when you consider what the bloodstream sees post-digestion/absorption; that is, glucose plus fructose plus the glucose and fructose liberated by digestion of sucrose.

    If it is the fructose that is primarily of concern here (and I am not convinced it should be), for consistency you should also warn people about these natural foods which are otherwise generally considered to be health-promoting. One good-sized banana contains about 20g of sugars which are, post-digestion, about equal parts glucose and fructose.

    But if it seems a little silly to warn people away from bananas, apples, kiwis, and oranges because of their substantial fructose content, then you might wish to also question the validity of your warnings about HFCS and table sugar. Sugars are, after all, sugars, regardless of source.

    In my opinion, it would be better to emphasize the issue of empty Calories vis-à-vis refined sugar instead of labeling as “bad” these naturally-occurring and ubiquitous sugars.


    • Toxins

      Excellent point Dave!

      You should take note that although fruits may have a lot of sugar, it is different from that of table sugar or that of high fructose corn syrup. For example, Dates are 80% sugar and do not raise blood sugar and they lower triglycerides. Check out Dr. Greger’s video on the topic: In regards to the artificial sweetener Z sweet also known as erythritol, it is derived from the sugars of fruits and, similarly to dates, it does not raise blood sugar levels. Check out Dr. Greger’s video on the healthiest artificial sweetener although Dr. Greger’s video doesn’t explicitly state anything about not raising blood sugar, you can find more information on that here.

      Hope this cleared up any concerns!

      • Dave Stone


        My main concern is that you are being misled about sources of sugars.

        Fruit sugars are NOT different from any other sources of these same sugars. Glucose is glucose is glucose, and fructose is fructose is fructose, and sucrose is sucrose is sucrose, and the latter is composed of equal parts glucose and fructose. It really is that simple. Don’t let the bull throw you.

        Dates do not raise blood sugar? Well, what time frame are you referring to? Deglet noor dates are about 63% sugar by weight (according to USDA nutrient database) [24% sucrose, 20% glucose, 20% fructose], and after digestion of the sucrose in the GIT, 32% glucose and fructose both, which is then absorbed into the bloodstream. Glucose, from ANY digestible source, raises blood sugar (glucose) temporarily until insulin facilitates removal of the glucose and restores fasting levels. So, do dates raise blood sugar (glucose)? OF COURSE they do, temporarily, just like HFCS, table sugar, a banana, a piece of whole-wheat bread, popcorn, oatmeal, or any other of the hundreds of ordinary sources of glucose.

        They *lower* blood triglycerides? I wouldn’t bet the farm on that claim quite yet.

        Erythritol is not a sugar—it is a very weird sugar alcohol: it is absorbed pretty well (unlike various other sugar alcs), but is mostly excreted in the urine, unchanged, whereas most other sugar alcohols, if they are absorbed, are oxidized for their 4 Cals/gram of energy. Consumption of erythritol in amounts needed to sweeten foods is HIGHLY unnatural. It is itself synthesized by enslaved yeast in a highly suspect industrial process. [I’m ribbing you a little here–despite the above, it’s not considered dangerous]

        And their (dates’) nutrient content is so-so, despite what the Israeli folks said. This isn’t rocket science–look up the nutrient values yourself. They are readily accessible on-line at USDA’s nutrient database website. Considering the number of Cals provided by dates due to the high sugar content, their nutrient density is lower than for comparable weights of other vegetable foods. Dates are virtually devoid of Vit C, Vit A, Vit E, and like all plant foods, Vit B12. There is no single “perfect food”, but if I had to choose, I wouldn’t choose dates or broccoli. I’d choose whole animal bodies (minus a few parts). They have the same nutrient content that we do for obvious reasons.

        Just trying to keep things real here…it’s hard work.


        • Sorry, DS, fraid I gotta drop the paleobomb on you: I wouldn’t choose animal flesh, ova or secretions for the following reasons: parasites; pathogens; endotoxins (cooking doesn’t work here); carcinogens; saturated fat; excessive protein; hormones/hormone mimickers; agribusiness chemicals; poor phytonutrient/antioxidant content; unethical treatment of animals; environmentally unsustainable production methods; and there are much better choices for all necessary nutrients. Watch the rest of the Dr, G videos on meat/dairy before responding. My paleopatrol complete, now I’ll step back.

        • Sean

          Whole animal bodies? good luck with that.

  • Dave Stone

    Toxins, fruit-derived sugars are not different. Fructose is fructose, glucose is glucose. Dates are just like other common natural sugar sources, about 50:50 glucose and fructose once digestion is done. The glycemic index of dates is around 50, and that doesn’t mean that they do not raise blood glucose–they most certainly do. Other concentrated and/or refined sweeteners are in that G.Indx ballpark as well, from honey to table sugar. The higher the fructose fraction of a sweetener (relative to glucose), the lower the G.Indx value, as fructose has little effect on blood glucose. Dates have a fair amount of dietary fiber, and that may slow stomach emptying somewhat and hence somewhat lower their G.Indx.

    Israeli study or no, dates are, as sources of essential nutrients, fairly ho-hum. Simply look them up in the USDA foods database online to see what half a kilo (500 grams, 1400 Cals) of dates provides—nowhere near the range of essential nutrients an adult (or kid) needs each day, and virtually devoid of several vitamins and minerals. Never believe anyone who says that a single food is “the perfect” food for people. No such thing. There are many ordinary foods (most vegetables, for example) that blow dates out of the water in terms of nutrient density.

    No doubt had the Israeli study had a maple syrup or honey control group, the results would have been about the same. What the study shows is that eating sugars is not harmful. And why would it be? These are normal components of natural primate foods. Starch is 100% glucose, and refined or not, has a potent effect on blood glucose. The advantage of HFCS, table sugar, and most nat’l sources of sugars in this regard is their fructose content.

    Sugar alcohols are a whole ‘nother ballgame.

    • MR

      DS, look at the studies. Instead of philosophising, actually take the time to read them… the USDA nutritional info does not predict how food is going to affect the body.

  • jojo

    The biggest question I have is, how would you rate sugar from an apple verses sugar from a juiced apple verses sugar from store bought clear apple juice verses table sugar. I know that the body needs sugar, otherwise we never would have developed a section of our tongue dedicated to it. I just want to be clear about it since I’m a big advocate of eating whole foods and juicing.

  • Asparagus

    Corn syrup is a lot healthier than sugar as it is made of glucose which is digested by the gut. Sugar and HFCS contains fructose, a poison that is metabolised by the liver in a similar way to alcohol, and when consumed in excess without dietary fibre (as in processed foods, sweeteners, fruit juice, soda) it raises pattern B LDL cholesterol levels, triglycerides and insulin resistance – all of which cause metabolic syndrome which is the primary cause of obesity, diabetes and hypertension in the U.S.

    Can you comment on any of the research that blames fructose, not saturated fat for the obesity epidemic in the U.S.? (Yudkin 1988)

    • Toxins

      Are you suggesting that fruit consumption is unhealthy due to the fructose content? this is simply nonsense. All sugars are converted to glucose. You present no studies to back up this claim and are throwing out years of research linking saturated fat and excess caloric intake with obesity. Fruits are not the cause of obesity.

      • Asparagus

        No not fruit consumption, fruit juice. Eating a serving of fruit makes you full because of the fibre it contains (an orange for example), whereas drinking a glass or two of orange juice contains the fructose of 4-8 oranges with no fibre whatsoever, unless you are very active it will not be converted to glucose. It is rapidly metabolised by the liver much like alcohol is and does not contribute to satiety or trigger the insulin response that glucose would, which means much of it ends up being converted to fat (the bad kind: pattern b LDL) in the liver which causes non-alcoholics fatty liver disease and consequently, metabolic syndrome.

        This goes the same for any heavily processed foods with added sugar or HFCS but you asked about fruit, fruit juice is obviously not as bad as other high fructose foods as it contains phytonutrients, antioxidants etc. but my point is that excessive juice consumption can also be very dangerous.

        Here is a study demonstrating the effect of high fructose metabolism:

        This explains why the Inuits only started developing regular occurrences of cancer and heart disease when they adopted western diets, despite living on diets consisting almost exclusively of fatty animal meat and organs beforehand. (They had short life expectancies but very little disease)

        • Toxins

          We are in agreement that fruit juices are not the same as fruits, and I would not recommend fruit juice as a healthful choice.

          I do not necessarily agree with your theory on the inuits, as you pointed out, their lifespans are short. 10 years shorter on average. This is not something I idolize.

  • William Nields

    After watching “sugar: the bitter truth” on Youtube, it seems that fructose does lead to metabolic syndrome…when consumed in large quantities. Thus, fruit consumption as part of a whole foods plant based diet would not likely cause harm. However adding fruit juice to a diet full of processed foods (of which it is said 80% contain high fructose corn syrup) could be a recipe for obesity and diabetes. So in the end, avoiding processed foods is very important to preventing disease, and fruit (fructose and all) has a place in a healthy diet. It is so easy to get bogged down and confused in the details of nutritional biochemistry. I prefer to take a step back and look at the forrest. It’s really pretty simple, as Pollan put it “eat (real whole) food, mostly plants, not too much.

  • GotGout

    I have a problem with gout. What I understand now is that fructose can contribute to an attack. I think that corn syrup (100% glucose) in moderate amounts (1 teaspoon in oatmeal) would be idealistic for a sweetener. Would this amount be harmful?

  • Latha Shivakumar

    Your video indicates that high fructose corn syrup is just as bad as sugar. Are there any new data that indicates that high-fructose corn syrup can cause diabetes? I read about a study where the scientists found a correlation between the high incidence of diabetes in countries that consume a lot of high fructose corn syrup.

  • WandererAwakening

    Is Roundup herbicide found in corn syrup made from GMO corn. If so, it seems like that would make it worse that organic sugar grown without Roundup?