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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. I don’t crave sweets. I do think sugar is toxic. If it’s not, I still think it’s best to be avoided and has ill effects. I have a jar of raw honey on the counter. I add a bit to high-fat yogurt just so I can get rid of it. I probably won’t buy anymore of it. It has too much sugar. I used to crave chocolate and dairy. I don’t anymore. Like Polly said, I too think cravings for sweets is due to a nutritional deficiency.

  2. Here is some important information especially for chronically ill and overweight people

    CLA counteracts the effects of fructose

    “In conclusion, CLA in high-fructose diet, decreases serum LDL+VLDL and TG and plasma MDA concentrations as well as liver weight and liver cholesterol, thus opposing the effects of high-fructose diet and showing a potential antiatherogenic effect. Similarly, dietary CLA fed at 1% level (w/w) in high-fructose diet, prevented steatosis observed histologically in livers of rats fed high-fructose diets.”

    Fructose has been implicated in diabetes and obesity etc.

    I have been taking CLA for some years. There was a year my metabolism suddenly broke and I couldn’t lose any weight either through diet and exercise.

    CLA resolved the problem but it took me 7-8 months before I even started to see any results. I am chronically ill. I did it with no exercise or dieting. Belly fat stays off my waist with no effort. I have given it to a few other people and they have shown much quicker results.

    They say you MUST exercise and MUST diet. The problem with this is that chronically ill really people can’t exercise so it is hollow advice. People can also have joint and spine degeneration (which there is a cure for) problems.

    This is an important WARNING for people who use CLA

    1) You will gain weight before you lose it. The weight scale is useless because you will gain muscle and muscle weighs more. You pinch the fat on your waste with your fingers to guesstimate how it’s going. I had zero results in first 6-7 months probably because my body so was broken.

    2) How long it takes to work varies in each person so not something for someone who doesn’t have patience. This isn’t a quick route or immediate gratification.

    3) Never take on an empty stomach. I usually took CLA usually after meal. I’ve even take it an hour after a meal a few times. Food needs to be in stomach.

    4) The CLA needs to build up in your system. I took 6 capsules a day. I just concentrated on building it up in my system and nothing more.

    I remember during the 7th month waking up one morning and feeling a little different especially weight wise but just thought it was my imagination. I wasn’t even thinking of the weight loss for many many months. I pinched my belly and realized that fat was melting away and all the other wrong places.

    CLA has been scientifically proven to be one of the few proven ingredients for weight loss.

    I do think it counteracts diabetes also.

    I wonder how many people who have taken CLA just quit because they didn’t understand how it worked or got on the scale and declared it a failure after they saw weight gain.

    Given it’s ability to counteract fructose, this may be worth trying even if you have no weight problem.

    This is something to consider trying if you haven’t tried it.

    • Interesting information about CLA, it sounds similar to taking L-Leucine with glucose and Reservatrol. I have found D-Ribose really takes away any cravings for sweets.

    • Just a clarification about CLA (Conjugated Linoleic Acid). I use the phrase “weight loss” in above post but I should say FAT loss. This is where the real focus needs to be.

      My maintenance is 2-3 capsules a day. If I eat at a buffet I will boost it up to 5 or 6 capsules.

      Research would suggest that people who have hypothyroid tendencies would definitely benefit but non hypothyroid people benefit also.

      Just to give some hard data … I am 6’2″ tall 59 years old male

      Before I developed weight problem … 215 lbs 42 waist … slim

      After I developed weight problem … 260 lbs 54 waist

      After taking CLA … 250 lbs 44 waist … slim. Even less belly fat than when I was 215.

      My weight can vary between 245 to 265 and I still stay slim with 44 waist. I don’t work out. I just swim a couple days a week. I’ve had my pants nearly fall off me many times. I need to make sure the belt is tight.

      If I wanted to, I could easily cut down my weight by removing some hidden muscle by burning it up with exercise but muscle burns fat so won’t.

      Ultimately the shape of your body and composition (fat and muscle) of the weight is really what counts. Don’t get focused on just the number on the weight scale. I realize it is hard to do especially if you have been conditioned to do that. Just stick with pinching the fat on your waist.

      CLA has been the subject of a variety of research in the past several years, and findings also suggest that some of the other benefits of CLA include the following:

      Increases metabolic rate — This would obviously be a positive benefit for thyroid patients, as hypothyroidism — even when treated — can reduce the metabolic rate in some people.
      Decreases abdominal fat — Adrenal imbalances and hormonal shifts that are common in thyroid patients frequently cause rapid accumulation of abdominal fat, so this benefit could be quite helpful.
      Enhances muscle growth — Muscle burns fat, which also contributes to increased metabolism, which is useful in weight loss and management.
      Lowers cholesterol and triglycerides — Since many thyroid patients have elevated cholesterol and triglyceride levels, even with treatment, this benefit can have an impact on a thyroid patient’s health.
      Lowers insulin resistance — Insulin resistance is a risk for some hypothyroid patients, and lowering it can also help prevent adult-onset diabetes and make it easier to control weight.
      Reduces food-induced allergic reactions — Since food allergies can be at play when weight loss becomes difficult, this can be of help to thyroid patients.
      Enhances immune system — Since most cases of thyroid disease are autoimmune in nature, enhancing the immune system’s ability to function properly is a positive benefit.

      • Thanks for the info. I remember when I was eating a lot of yogurt I was much thinner. Yogurt is a good source of CLA. I’ve started up again and will check out CLA supplements.

  3. I agree with Chris, that sugar in small doses is not toxic.
    It’s just that in our modern diet, limiting ourselves to small doses is pretty difficult, and refining sugar has meant its omnipresence in our food, and in more places than we realize.

    I can’t help thinking of ‘refined’ as ‘processing unwanted elements’ but also ‘elegant and cultured manner and taste’. Alongside the origins of refined sugar, available strictly for the wealthy, and in small amounts because of short supply, it’s only with the industrial revolution where we mechanized our refining of sugar (and culture?) that there was so much of it and as is often the case, excess became toxic?

    Maybe sugar is neither good nor bad just in or out of balance as you explained so brilliantly in your previous/first article in this sugar series – (http://chriskresser.com/is-there-any-room-for-sweeteners-in-a-healthy-diet) 🙂

  4. Chris,
    Can you address the “fructose is metabolized in the liver” issue? Also, in reading about HFCS it seems that it is processed to alter the the chemical composition (turning some of corns glucose molecules into fructose). Does this play a role in the it’s bad reputation?

  5. I’m so delighted you’ve brought this up. I used to believe I was addicted to sugar and spent my life ‘fighting’ my urges – then giving in and bingeing. I was bulimic as a teenager and spent most of my adult life with BED. My biochemistry I would guess is pretty much the same as it always has been (question for the doctor?!) – but I no longer believe as though or behave as though I’m addicted to sugar. Giving myself permission to have it, without guilt, has transformed my life and my relationship with sugar and carbohydrates. I do eat them from time to time, but this no longer pushes me over the precipice down the slippery slope.

    • Similar story here…I allow myself reasonable amounts of organic dark chocolate, sans guilt, and no longer feel the compulsion to eat the whole bar.

      And, Trader Joe’s spicy peanut vinaigrette is a staple in our kitchen. Sugar is the second ingredient on the label. I figure as long as I limit amounts and am eating it with plenty of fiber (love it on grated carrot/sauerkraut salad), it shouldn’t be an issue. I also mix it with additional peanut butter, which I think helps defuse the sugar impact. Of course, I use good quality peanut butter, organic if possible.

    • There is a grey area in this so called sugar addiction. There are foods I really like but they are healthy. Am I addicted to them also. I just use moderation. Usually after I eat something, I don’t want to eat it as much anymore. I want and desire variety. I get bored with any particular food really fast.

      Historically going back to the early 1900s, the average intake of sugar was 60 to 70 grams per day. I try to stay within or below that range MOST of the time. It’s pretty easy. If I see something I really like then on occasion I will intake 700,000 grams (LOL). I will usually skip 3 to 4 days because I just don’t feel like eating anything overtly sugar. I will eat fruit on those days.

      When I eat, I try to eat within an 6-8 hour period so my stomach is resting for 16 to 18 hours a day.

      Here is some things i recently ate

      I drank 3 large bottles of Sierra Mist (uses sugar) recently but that was first soda I had in 6 months. It has 37 grams of sugar per 12 ounces. I generally stay away from soda.

      I’d rather make a lemon meringue pie (i use almond milk and 1 1/4 cup of sugar). I can eat half the pie and be within a reasonable range of the overt sugar.

      I found this big box of danish that has high quality ingredients in it. Haven’t had a danish in a while. I haven’t felt like eating any more danish in a while.

      I don’t deny myself except if i am experimenting with something.

      The body generally utilizes glucose well but not fructose so I try to make

      I think the person who says that we have individual situations so one size advice doesn’t fits all. I think people who have to battle problems all the time have something key that is still broken whether it is metabolism, gut problems or infections in them and not addressed. I understand the frustration that people have in trying to solve them.

  6. Hi Chris
    I’m know to stay away from the corn syrup and beet sugar so I try to buy cane sugar when sugar is needed, usually for making kombucha or kefir. But I see different kinds of cane sugar; brown, golden, natural, sugar from crystallized organic cane syrup, extra fine grains, fine grains and on and on. How are these processed? Is it better to choose organic vs non-organic? Are some choices better than others? Any info you can provide is very helpful. Thanks

  7. I hope that you will cover Dextrose and D-Ribose as well. This is a very informative series and great reference. My particular interest at the moment is glucose interaction with leucine and which is the better provider of glucose.

  8. It appears that excess carbohydrate/glucose consumption may be responsible for health problems than go beyond obesity or difficult to control weight gains.

    “A poor diet can eat away at brain health. Now a study in Neurology suggests that eating a lot of sugar or other carbohydrates can be hazardous to both brain structure and function. … These findings indicate that even in the absence of diabetes or glucose intolerance, higher blood sugar may harm the brain and disrupt memory function. Future research will need to characterize how glucose exerts theses effects and whether dietary or other lifestyle interventions might reverse such pathological changes.” —Emilie Reas, Scientific American Mind, July/Aug 2014.

    The original study was conducted by researchers at the Charité University Medical Center in Berlin.

  9. I grazed through the comments for a while and a couple reminded me of a great line by the long lived cigar smoking George Burn:”
    If I knew I was going to live this long, I’d of taken better care of myself”. I always have to remind myself when I advise/soapbox, we are all similar and perhaps spiritually equal. But physically we are as varied as snowflakes. 🙂 just ask Pasteur about when that nut case drank his tube of anthrax toxin and it didn’t even phase him. If you have a physical malfunction similar to one I’ve mediated, I can tell exactly what I did, and it may or maI was y not help. My hope is always to assist, but ‘let the buyer beware and do his own due diligence’. Even Kris knows he doesn’t know everything. He’s good mind you, but even with science, people are built with wide varieties. That’s what make the AMA /big Pharma philosophy so heinous. It is based on the notion that everyone is identical. I’m not even like I was five years ago. Things change; entropy is.

  10. By the by, it is my understanding, that excess fructose is processed by the liver like fat. When the liver overloads with it it starts cranking out uric acid. So joint problems like gout can be a result of too much high fructose food items/soda pops/deserts. HFCS is proliferate in many foods, like granola bars, ad nauseum.

  11. it is my understanding that cane sugar, while still in the cane actually contains B vitamins. Turbinado, therefore as well. In the same way sea salt is different than ‘rain but still pours’ salt. It is the trace elements that make the difference. So, ‘naked’ sodium chloride is harmful when sea salt is not because the body needs the trace element/minerals to properly use/assimilate the sodium chloride. Likewise, the body needs the B vitamins plus the other trace minerals in the cane to digest/assimilate it. Processed sugar and processed salt will leach the needed chemistry from the body to properly be digested. Sugar solutions are exactly what is used in peritoneal dialysis to draw excess water/fluid from the blood. So, it would follow that concentrated sugars would in turn leach fluid/water, leading to dehydration symptoms/malfunctions. Processed/White flour can be delineated to show similar digestive/system harm. Anytime ‘White’ is promoted in food processing because it’s pretty, it’s pretty bad. Now about this business of White teeth………

  12. I am really happy to see you are suggesting a more balanced approach, Chris. I really enjoy this new direction you seem to be taking. Keep up the good work.

  13. You state that “regular sugar is simply sucrose, a disaccharide composed of one glucose molecule and one fructose molecule bonded to each other.” I have read that while HFCS is also fructose and glucose, unlike sugar which is a bonded molecule, HFCS fructose and glucose remain two discrete molecules and your body doesn’t know how to handle it. Therefore HFCS “sugar” ends up stored as extra fat in your liver. Is this a reason why obesity has exploded since the 70’s when HFCS became the commercial sweetener of choice in the manufactured food industry?

  14. I am a sweets addict. If I crave sweets (which happens pretty often), I PACE if I can’t find anything, or I will INVENT something/ANYTHING from brown sugar, sugar or even honey, but honey isn’t really sweet enough.

    It’s a horrible, overwhelming thing, much like drug addicts must feel. I have to be very careful because I am also pre-diabetic. If I eats sweets, then I crave them MORE- I call it “feeding the demon”. I wish I wasn’t like this, because it is a constant battle. I fight to the best of my ability and I am eating clean as much as I possibly can.

  15. As someone who has promoted sugar-free living for a few years, I’m delighted to see you tackle this topic with your investigative, evidence-based approach, Chris! I do wonder about the emerging evidence concerning the connection between overeating and sugar consumption. Based on my personal experience, I wonder if we don’t fully understand the mechanism that triggers lingering cravings and subsequent overeating after the consumption of a high sugar meal. Honey, maple syrup, and other “natural” caloric sweeteners seem to have similar effects. In spite of what the evidence says at this point, I know that there’s no other food that makes me want to go back for seconds like sugar!

    Glad to see that xylitol is getting more press! I prefer erythritol myself because xylitol can cause some unpleasant digestive side effects. Here’s a study comparing the two sweeteners:

    What’s your take on the GMO issue? Sweeteners like xylitol and erythritol are 99.9% pure, and don’t contain genetic material in the crystalline product, to my knowledge. I frequently receive questions concerning the source of erythritol that I use, and so I wanted to hear what you had to say about that.

  16. I am addicted to sugar, and have tried to give it up countless times since I was ten years old. When I try to stop eating sugar, I have shakes and aches and feel depressed and anxious, and hungry no matter how much food I eat. One packet of sugar in a glass of water and I feel normal again.

  17. I avoid white sugar because of how I feel often when consuming food that has a high content refined sugar. My system feels off. Especially problematic was when I had a parasite. Then the sugar seemed to amp symptoms up more. Generally, I feel and run smoothly when I don’t eat foods with sugar or sweeteners, but can’t say I completely screen it out all together. . .sometimes I indulge in chocolate cake on birthdays and special occasions.

  18. Hi – also I use Yucon Syrup in my home made baking – it is a low glycemic sweetener, what is your thoughts on this? Or would you recommend something else?