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Is Refined Sugar Really Toxic?


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refined sugar, refined white sugar
Is refined white sugar really as toxic as we've been led to believe? istock.com/YelenaYemchuk

So far in this series, I’ve covered a variety of ‘alternative’ sweeteners: natural sweeteners like honey and stevia; artificial sweeteners like aspartame; and sugar alcohols like xylitol.

But what about plain old white sugar? And what about the increasingly common industrial sweetener, high fructose corn syrup? These two get a pretty bad rap, even from mainstream media, and although much of their reputation is deserved, there are some misconceptions that I’d like to straighten out.

The sweet (and not so sweet) truth about refined sugar.

The Evidence

Most of you are probably aware that excess refined sugar isn’t great for your health. Sugar and HFCS are particularly detrimental when consumed in liquid form, because we don’t tend to compensate for calories we drink by reducing our calorie consumption elsewhere. (1) This can lead to weight gain from overeating, along with elevated triglycerides, insulin resistance, and other indicators of metabolic syndrome.

Refined sugar has also been implicated in reduced immune system efficiency. (2, 3) In one study, immune cells demonstrated a significantly reduced capacity to kill pathogens (e.g. viruses, bacteria) following sugar consumption (from sucrose, glucose, fructose, honey, or orange juice) when compared with fasting levels; starches didn’t have this effect. Unfortunately, this study was quite small and I haven’t found further evidence to corroborate or refute these results. I believe it’s a good idea to avoid sugar when your immune system is compromised.

Refined sugar is also thought to promote cancer growth by ‘feeding’ the cancer. While it’s true that cancer feeds on sugar, it actually feeds on the glucose in your blood; not necessarily the sugar you eat. (4) While those two factors are obviously linked, it’s more important to be aware of your own blood sugar control, and don’t consume more sugar (or carbs in general) than you can effectively metabolize. After all, you will always have glucose in your blood as long as you’re alive, so the goal is to avoid having high blood glucose over a prolonged period of time, not to eliminate glucose entirely.

But while there’s plenty of evidence that excess sugar or HFCS can be harmful to health, there’s  actually no evidence that small amounts of refined sugar in the context of a nutrient-dense, whole foods diet (and active lifestyle) is harmful. The problem is that limiting yourself to small amounts of sugar is often easier said than done.

Is Sugar Addictive?

Addictive properties of sugar have been observed in rat models where food is restricted for 12 hours, encouraging a binge-like pattern of consumption. (5) These rats experience dopamine and opiod release that resembles the neurological response to substances of abuse, although significantly smaller in magnitude. Additionally, these rats experience opiate-like withdrawal symptoms after being given an opiate-blocker, or after a period of fasting.

Most human studies, however, have not reproduced these findings in rodents. (6, 7) (As always, it’s worth noting that the second reference was partially funded by the World Sugar Research Organization.) At least one small study which interviewed obese individuals did find that, based on self-reported symptoms, some obese patients fit the profile for sugar addiction, particularly those who also suffer from binge eating disorder (BED). (8) But as of yet, there’s little to no rigorous evidence that sugar is chemically addictive in humans.

However, some evidence does indicate that sugar can interfere with the normal hormone signaling from ghrelin and leptin, both of which help control appetite and satiety. (9) So although this isn’t an ‘addiction’ mechanism, it’s another way in which sugar can encourage overconsumption in susceptible individuals.

Whether sugar is addictive or not, from a practical standpoint, it’s often easy to eat more sugar than you mean to. Certain people are going to be far more sensitive to these effects than others, so it’s really a matter of being familiar with your own eating behavior when it comes to potentially addictive foods.

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Is High Fructose Corn Syrup Really Worse Than White Sugar?

So far, I’ve been talking about white sugar and high fructose corn syrup (HFCS) somewhat interchangeably. But HFCS is without a doubt the more vilified of the two, both in the natural health community and in mainstream media. Foods and beverages sweetened with “real sugar” instead of HFCS are seen by many as ‘healthier’ and more ‘natural,’ and even big soft drink companies like Pepsi are trying to cater to the ‘natural’ crowd by offering “made with real sugar” sodas. If HFCS can make sugar look like a health food by comparison, it must be pretty terrible for you, right?

Well, first, let’s talk chemical composition. White sugar, or ‘table sugar,’ is simply sucrose, a disaccharide composed of one glucose molecule and one fructose molecule bonded to each other. This means that table sugar is always 50% glucose and 50% fructose.

Contrary to popular belief, HFCS has about the same amount of fructose as white sugar. It’s also the same level of sweetness. (10) The two most common forms of HFCS in our food supply are HFCS-42, which is 42% fructose, and HFCS-55, which is 55% fructose. This is certainly “high fructose” compared to regular corn syrup, which has no fructose, but most people hear “high fructose” and think ‘mostly fructose,’ which is definitely not the case.

The main difference is that the fructose and glucose in HFCS exist primarily in their free monosaccharide form, instead of as the disaccharide sucrose as in table sugar. And given the similarities between the two sweeteners, it should come as no surprise that HFCS does not have significantly different metabolic effects from sugar. (11, 12)

I know many of you are also concerned about GMOs in HFCS. Genetically modified varieties of both sugarbeets and corn are grown and consumed in the US, with corn much more widely so. (13) Overall I’d say you’re probably better off with table sugar rather than HFCS from a GMO perspective, because it’s produced from crops that are less commonly GMO. It’s also pretty easy to find organic, non-GMO sugar.

So, How “Toxic” Are Sugar and HFCS?

White sugar and HFCS are not “toxins” in the sense that even small amounts are highly undesirable and potentially harmful. Excess refined sugar can have undesirable health effects, but its addictive power is not comparable to a drug, and HFCS isn’t that much different from table sugar. Some people may be highly sensitive to even small amounts of sugar, often due to severe gut dysbiosis, and in this case they’re justified in avoiding it vigilantly.

But barring extreme sensitivity, there’s no evidence to indicate that refined sugar (or HFCS) is actually toxic in moderate amounts, and most people would be better off avoiding the stress that comes from being unnecessarily fearful of any food that has even a trace amount of refined sugar in it.

I’d even go as far to say that intentionally consuming sugar on occasion shouldn’t be a problem for most people. If every now and then you decide to indulge in a piece of dark chocolate or have a scoop of real ice cream made with refined sugar, you shouldn’t mentally and emotionally beat yourself up or force yourself into a week-long “detox” to make up for your dietary transgression. The stress that comes along with excessive food restrictions can be much more harmful than having a bit of refined sugar here and there.

Sugar is neither a toxin nor a replacement for real food. Ultimately, small amounts of sugar can fit into a whole foods, nutrient-dense, healthy diet, as long as you recognize it for what it truly is: a treat.

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Join the conversation

  1. This article is Chris’ sugar addiction justifying his occasional sweet transgressions. Just kidding with you, Chris.

  2. What is “addiction”
    Experience shows for example, that children who eat lots of sweet things lose the ability to appreciate the “bitterness” of most vegetables and many fruits and are therefore “forced” to consume only sweet food stuffs. Is this “addiction”?

  3. Wow, long discussion, and not sure I want to wade through/wait for a reply, but still looking for clarification on the fact that in Chris’s book, “Your Personal Paleo Code”, on page 79, in Chapter 4 (Three Foods to Avoid: Minimizing Toxicity in Your Diet), Chris lists refined sugar as one of three toxins to eliminate, and I quote: “Refined sugar (in a word, toxic)”. “Toxic” is in italics.

    Hoping someone will clarify.


  4. Hi i work out and the suggested post workout shake comprises of simple sugar ie glucose and protein powder, as much as 20/30gms ive seen of glucose in one serving. Is this too much at one time? Are starches such as Vitargo or Waxy maize different to sugar ?

  5. Hello Chris, great post. I appreciate you for considering such important topic for writing. I really enjoyed reading important facts about refined sugar & it’s toxicity limit without our body.

    Few years earlier I used to eat refined sugar a lot with tea, coffee, & milk. Consuming sugar a lot can cause diabetes problem & for the fear of that I decided to eat raw sugar as less as possible. My wife helped me a lot quitting sugar & now I’m totally a occasional eater of refined sugar.

  6. I am so glad to see a reasonable approach to this topic. I have been one that has read labels and dutifully avoided refined sugars almost to a fault. I have indulged in an occasional treat if it has organic cane sugar or juice since I figured organic meant no GMO. This article really takes the stress off trying to eat clean and avoid things that are harmful to the body. Thank you very much for this information.

  7. I am much happier to go for mascavo sugar or rapadura rather than a highly processed sweetener.

    completely unhappy to eat any manufactured food in which the manufacturer decides how much sugar and other goodies to put.

    and after a hard workout, some simple carbs are great!

    i am most interested to understand the effect on feeding our bad gut bacteria – is white sugar worse than whole sugar? is there less effect if taken after hard exercise? is there less effect if eaten with substantial fat or protein?

  8. The body doesn’t metabolize HFCS as it does sugar. Excess HFCS stays in the liver and actually can lead to fatty liver — which has been discovered at autopsy in young people. Of course, no one would recommend too much of either, but too much HFCS carries the added damage to the liver. Unfortunately, it’s *everywhere* in the food system, though some companies have switched back to sugar.

  9. Hi Chris,

    great article. It’s like Paracelsus said: “The dose makes the poison”. Period.


    • I’m not arguing for or against sugar, either table sugar or HFCS — but that quote you just *ahem* quoted:

      “The dose makes the poison.”

      Oh boy, is that ever wrong!

      Let’s talk real poison for a minute, arsenic. If someone were to put even trace amounts of arsenic in your food — would you knowingly eat it? (Remember, I said trace amounts, that goes back to what you said about “dosing.”)

      The trouble with your argument is, poison is poison, no matter how you look at it. Taking more of it will kill you right away; while taking less of it will kill you over a period of time.

      It’s up to you how you want to die: Right away, or slowly and painfully over time. It’s quick death vs. gradual death — and neither something you should strive for!

      • Technically your right but Tom is right generally speaking over the long term when talking about HFCS and less potent toxins. The frequency which one takes HFCS is I think another factor.

        The average person drinks 60 liters of soda per year. That works out to 11 pounds of HFCS. Soft drinks are the worst. Then you add in the other food which works out to 60+ pounds a year.

        People can handle toxins in different degrees. I think back in the 1960s the average consumption was 10 pounds so I would guess anything under 20 pounds healthy people in general can handle.

      • Actually, “trace amounts” of arsenic in food or water are more common than you seem to think.

      • The dose DOES make the poison. That’s the basis of the science of toxicology. Carcinogens are the exception, as we still don’t understand the exact mechanism by which they cause cancer, so it is (theoretically) possible that a single molecule could trigger cancer. But for other toxins, they really are dose-dependent. Even arsenic, which is, BTW, present in many soils naturally. While I would not go out of my way to eat even a low dose of arsenic, I know as a scientist that low concentrations are present in many whole, natural foods. If you are going to eat, you are going to consume toxins, even if you consume an organic, pristine diet. Many toxins are (and have always been) present naturally. The allowable levels of toxins are set based on the amount the body can process without apparent harm. Note that the toxicity of a given compound is “route-of-entry” dependent as well — an amount of arsenic (for example) that would kill you if consumed by mouth may have no harmful effect if applied to your skin. And remember, too, that there are compounds and elements like copper and selenium that are essential micronutrients in small amounts, but are poisonous at higher concentrations. Because you have selected an element (arsenic) that may not be essential in the human diet, that does not negate the entire basis of toxicology.

      • USA drinking water can have up to 10ppb of AS1 (inorganic arsenic). Arsenic is also naturally occurring and present in many things we eat & drink…including fruits & vegetables

    • Absolutely. For me ANY SUGAR makes me unstable and poisons me. After 40 years of torture, I have more energy than even as a child. Am completely emotionally stable and at peace. NEVER sick. No flu. No colds. No sinus. No arthritis etc. After a lifetime of these sicknesses and severe depression, I’m ten years clean of sugar. Pure poison. For me anyway.

  10. I agree with what you are saying and was going to share it but one problem, from what i have come across in several articles is that HFCS contains mercury. Which, in turn, will make it a toxin and regardless of how low the levels would be, it doesnt justify it as okay. Id like to hear your thoughts on that.

  11. I don’t think of sugar as the enemy. I avoid using it on a daily basis and avoid sweets mainly because of weight gain. I also enjoy an occasional ice cream cone in the summer. Since I have 6 children and 11 grandchildren I am called on occasionally to make birthday cakes for one or another. do I indulge at the party? Absolutely! Do I beat myself up? No, but I do reduce my calories for a while to compensate. I guess I use my Dad’s motto which is “everything in moderation”

  12. I suspect that the worst of the overconsumption problems people generally associated with “sugar” are actually a result of the engineered flavor additives that make sweet tastes more distinctive and more rewarding. I doubt that many people would find sucrose/fructose addictive by itself. It is “toxic” only in the sense that overconsumption leads eventually to problems with blood sugar regulation that make the levels in our blood toxic. I think the focus often placed on making sugar itself a toxin may be somewhat based on some faulty premises and extrapolations from epidemiological data that uses too broad a brush.

    I wonder if we should instead be focusing our attention on dealing with the ways that sweet flavors have been enhanced commercially, either by getting individual control over the ingredients in our food or by finding ways to encourage food providers to provide options that focus on nutrition and natural flavors rather than flavor reward and variety. Just my thoughts, fwiw.

  13. I ate a lot of sugar in the past, in my childhood. I remember everyday going to the shop and buying all kinds of sweets. When I think of those time right now I get ugly feeling and question myself how could I do that every day?

    Right now I’m avoiding sweets and sugar. I stay away from all candies and sweets as far as I can :D.

  14. I think that some white table sugar and sugar in processed foods is made from GMO beets. It’s best to look for “cane sugar” on the label to be sure that you’re consuming real cane sugar. Otherwise, it’s probably GMO beet sugar.

  15. This article is an example of why I trust Chris Kresser. He doesn’t subscribe wholesale to any diet dogma, but rationally and objectively surveys the data and recommends dietary guidelines. When folks get married to certain ideas about diet and food (as evidenced by many comments here), they can’t stomach (ha-ha) any information that doesn’t reinforce those beliefs. I especially like how Chris points how stressing too much over what you eat perhaps being worse for you than eating the feared food. One thing that keeps me from getting too religious about food is this: I picture one of the billions of people who would be so grateful for the bun I carelessly toss in the garbage because it has, god forbid, gluten! It’s easy to forget how ridiculously first-world we must seem to most of the planet’s population.

  16. I know from first hand experience that HFCS can really pack on the pounds. A few years ago I eliminated any products that contained it, and they were many. That stuff is in everything!!! I lost a pound a week for the next 3 months from that one simple change. I didn’t reduce my sugar intake in any way and I was very happy to get back to a reasonable weight.