Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
29 Mar

Dear Mark: Sugar as Immune Suppressant

Dear Mark,

Since going Primal last summer, my vegan buddy and I have some very explicit differences of opinion. I’m sure you can guess where they come up. Where we agree though is on the subject of sugar, especially refined sugar (syrups, honey, HFCS, table sugar, etc). Neither of us eat the stuff as a rule, but we have different reasons for avoiding it. I give the standard list and his main contention is that sugar compromises the immune system. Is this true? Does eating sugar actually suppress the immune system? I’ve heard this before, but have yet to see hard proof. Thanks.

Thanks for the question. We already know sugar should be limited in the human diet. Most people can agree with that. Here are but a few of its effects on our physiologies. Fun stuff!

It leads to insulin resistance.

It promotes inflammation in the body.

It can lead to weight gain when ingested.

It contributes to non-alcoholic fatty liver disease. In fact, our livers process fructose very similarly to the way they process ethanol. Lustig calls fructose “alcohol without the buzz.”

It appears to act like fertilizer for cancer cells.

High fructose diets decrease HDL levels, while reducing the diameter and increasing the density of LDL particles.

Glucose and especially fructose can bond to – glycate – proteins and lipids without proper enzymatic control.

All that would be plenty justification for anyone to cut sugar from their diet, wouldn’t you agree? I mean, who wants glycated lipids wedging themselves between endothelial walls, or a cascade of inflammatory responses leading to weight gain and insulin resistance, or a bed of happy, hungry cancer cells enjoying a steady supply of food? Not me.

But you were wondering whether sugar really suppresses the immune system. It’s a charge often levied against the humble ivory granules, and, perhaps owing to their despicable record, it’s stuck. Sugar is an easy target to pick on, and it’s a sticky substance (at least when wet), so things stick.

As to whether sugar directly impacts the immune response, there is evidence that it does play a role: the often-cited 1973 neutrophilic phagocytosis study out of Loma Linda University. Neutrophils are small white blood cells, about 9 or 10 µm in diameter. They’re also the most abundant white blood cell, or leukocyte, in the body. Good thing, too, because they play a crucial role in the defense of the multicellular organism (that’s us). Neutrophilic phagocytosis is the process by which offensive microbes are dispatched by neutrophils.

The Loma Linda study observed the effect of sugar ingestion upon neutrophilic activity. After an overnight fast, subjects were administered oral 100 gram portions of either glucose, fructose, sucrose, honey, or orange juice. Blood was drawn before and after administration of the sugar, then mixed with a shot of staphylococcus epidermidis (a fairly common bacterial strain that can be virulent in compromised immune systems) to determine the neutrophilic phagocytosis response. After ingestion of sugar (but not starch), the phagocytic index (a rough measurement of the neutrophilic response) was significantly decreased, while fasting significantly increased the response. Sugar eating didn’t decrease the number of neutrophils; it simply decreased their responsiveness.

It isn’t exactly clear that sugar and sugar alone exerts a neutrophilic-dampening effect on our immune system. I’m inclined to think that the neutrophils aren’t lying dormant, befuddled and entranced by the fructose. Instead, I’m thinking they’re occupied by the rapid influx of twenty teaspoons of sugar into the body. Let me rephrase that: they’re occupied by the effects of the rapid influx of sugar. To understand what I mean, look at the start of this post. Check out all those negative, inflammatory effects sugar has on our body, and think about how twenty teaspoons of sudden sugar might necessitate an inflammatory response to deal with them all.

Who’s well-represented among the first wave of the inflammatory response, you might ask? Neutrophils. They are often the first responders to migrate toward the site of inflammation. Now, if a rapid influx of sugar can provoke an inflammatory response, and if that inflammatory response consists of neutrophils springing into action, it might explain the results of the Loma Linda study. Perhaps the neutrophils were dealing with the sugar rush. Maybe their cytoplasmic storage granules, which usually contain antimicrobial weaponry, were depleted after handling the fallout from all that fructose. In any case, though the Loma Linda study is suggestive, more research needs to be done on sugar and its possible immune suppressing effects.

What we do know is that it’s impossible (and shortsighted) to hone in on just a single factor. It isn’t just sugar that suppresses the immune system. It’s also stress. It’s too little exercise, or too much. It’s lack of sleep. It’s the SAD. Whatever contributes toward chronic inflammation, weight gain, excessive cortisol, and the metabolic syndrome is most likely also contributing to the compromised immune system. Sugar plays a role, maybe even a big one, but it’s not the only player.

We also know that people following the Primal Blueprint appear to be healthier. They’re the ones who survive flu season with nary a scratch, while their office mates take sick days and the trash bins overflow with used tissues. When they do fall ill, the turnover is quick and painless. These may just be anecdotal accounts, but they’re extremely powerful. Is it because of sugar avoidance? Seems likely. Whatever it is, though, it’s working.

So, sorry, Poppins. Keep your spoonful of sugar. It may very well help your spoiled wards choke down their medicine, but it could also make the problem – a weak immune system – even worse.

What are your thoughts? Have you noticed fewer colds and flus since ditching sugar and going Primal? Share your stories in the comment board!

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. When i went low carb the one thing i noticed right away was no heartburn. I was on medication for heartburn but I no longer need it when i cut out sugar and other high carb items from my diet.

    Jeanine Moffett wrote on March 30th, 2010
    • Funny you mention the heartburns; I had the same problem before going Primal.

      As for sugar, there is WAY too much of the stuff in our dietary environment right now. HFCS ought to be banned, period! It’s a nightmare when it comes to educate our own kids about proper eating…I mean, the stuff is in EVERYTHING! Personally, I stick to fruits and feel really good since then.

      That said, there is a mystery that I can’t find an answer to:

      If sugar is that bad for us, how come we have specific and dedicated taste buds for its detection right on our tongue?

      Evolutionary mistake? Or are we heaping too much scorn on the molecule?

      When it comes to nutrition, it pays to remember that complexity is the name of the game. The “certainties” we hold dear about nutrition can rapidly acquire the status of self-evident dogma.

      Dr. Frankie wrote on March 30th, 2010
      • Frankie – because finding fruit in the wild was usually a pretty nutritious thing. Finding cheesecake everyday in the mall isnt, though. Another case of “jungle surplus hardware” not guiding us so well in modern civilisation

        Rich wrote on June 27th, 2012
  2. Steven

    Try the liquid stevia, and use only enough to counteract the bitterness of the coffee, not enough to sweeten. I used to need about 12 drops of the stevia, and in my attempt to kick the sweet habit, have gotten it down to 2 or 3 drops these days. When I want it sweet, I use 4 or 5. I have been using stevia for years, but finally wanted to break the sweet habit. I still cannot stomach coffee black, but 2 or 3 drops of liquid stevia works to make the coffee taste good, but not sweet. Just my 2 cents.

    Sue wrote on March 30th, 2010
    • Sue, that’s just how much I use as well. 3 drops in my morning tea just to take the bitterness off. It really works and hopefully isn’t inciting an insulin response. It certainly doesn’t taste sweet.

      Paleo-Piper wrote on March 30th, 2010
    • Liquid Stevia? I’ll look for it this weekend and give it a shot. Thanks.

      Steven wrote on March 31st, 2010
  3. The article referenced below lists immuno-suppression as the very first problem with sugar. The reference for immune system suppression is the same one that Mark used:


    Damon wrote on March 30th, 2010
  4. I have not been sick in 6 years! I am a cancer survivor as well. So if anything my immune system should be completely F’ed from the chemotherapy. I think a lot has to do the the increase in real food in general as well as vegetables. I had been doing some sugar for the past few years honey mostly, some agave, maybe a cookie or something with evaporated cane juice. I am down to pretty much nothing now. Just occasional fruit. I love no being sick!

    kevin wrote on March 30th, 2010
  5. In my vegan years, I was getting 15 colds a year. Even at my “best” I would still end up with 6 colds a year. Since going Primal, this has been the first year I haven’t got sick. It’s almost like a miracle.

    Paleo-Piper wrote on March 30th, 2010
  6. I noticed that the nutrition facts label on raw honey says it has 0 grams of sugar. “Regular” strained honey says something around 16 grams per serving. I was wondering how this is possible – I assume it has to do with what they are counting as “sugar”? Is raw honey any better than “regular” honey in terms of sugar consumption?

    Also, I’ve read about raw honey as a natural remedy for seasonal allergies, because it contains bee pollen, so if taken over time, your body gradually adapts to the exposure and you no longer get a reaction from pollen in the environment. But I’ve only read this on websites devoted to selling raw honey… anyone have any scientific or unbiased source of info on this?

    Aimee B. wrote on March 31st, 2010
  7. I think what they are doing is creative ingredient listing it is not sugar it is honey so they added no sugar what i do now is count the carbs. I also heard that it was proven wrong that it helps with allergies but who is to say it seems like it should work

    Jeanine Moffett wrote on April 3rd, 2010
  8. So I’ve often heard people say that sugar has a ‘drug like’ effect on the body but lets be honest people, it IS a drug. Lets review it properties

    -It has no nutrional value

    -it causes hormonal and neurotransmitter responses

    -it’s addictive (not all drugs do this)

    -you get a comedown/crash (again, not all drugs do this)

    wonder what peoples reactions would be if kids started snorting lines of it?

    Joe90 wrote on April 6th, 2010
  9. This is a no-brainer to me…I have direct personal experience of this. I had colds constantly as a child, and they were obviously directly related to my blood-sugar level. I could drink a Coke or eat a candy-bar, and I might get sick. If I did both in the same day, I ALWAYS got sick. The only exception to that is when I would subsequently drink a gallon of water in order to bring my blood-sugar down.

    Joel wrote on April 8th, 2010
  10. I just go for the “no sugar” and “no diet varient” plan. This is also common sense. To much of anything can be bad and sugar as one of those things.

    Weight Loss Writer wrote on April 24th, 2010
  11. Agave “nectar” is a very confusing scam, it is no better than high fructose corn syrup. Diabetics have found this out the hard way. Table sugars of all kind, even ‘organic’ are detrimental to our immune system,especially children. If that is not a deterrent,perhaps vanity may help. Sugar greatly increases cross-linking (wrinkles). The only wild animal that has been found to have cavities and worse is the ‘Honey’ Bear. maybe that’s why they are so mean. Xylitol does not affect the pancreas-and is not considered a sugar. Buy only the xylitol made from the birch bark, not corn. Look it up.

    Angela, RN, CHC wrote on December 3rd, 2010
    • Actually, Agave nectar is much worse than HFCS – it’s almost completely composed of fructose – hence it’s “sterling” glycemic score. RUN AWAAAAY!!!

      Leaf Eating Carnivore wrote on December 6th, 2012
  12. Hmmmm, is it any coincidence that “flu/sick” season coincides with the sugar and stress and lack of sleep that is the experience of most people during the winter holidays?? And that for most of us in the US also involves a significant decrease in exposure to sunlight/Vitamin D?

    Carrie wrote on February 15th, 2011
  13. I never really get sick anyway, aside from a few deadly viruses which I beat in record breaking time.

    Alex Good wrote on April 3rd, 2011
  14. Another effect of sugar is that it competes with vitamin C – due to the similar chemical structure- to get into cells. Imaging what happens with your immune system when the white blood cells – that need large amounts of C to be effective – don’t get the required C due to the fact that sugar competes for the same access port. Could be one of the reasons why diabetics – with chronically high bloodglucose levels – experience scurbia-like symptoms.

    Andre wrote on May 26th, 2011
  15. One more argument against sugar. Sugar lowers the amount of magnesium in your body. And most people don’t get enough magnesium anyway.

    Now the nasty bit: a shortage of magnesium leads to a shortening of the telomeres, meaning the number of times your body cells can renew themselves becomes less. Or just plain : you speed up your aging.

    And sugar lowers testosteron in boys. Apart from libido, testosteron gives strong bones and strong muscles.

    Andre wrote on May 26th, 2011
  16. Has anyone heard of Coconut Sugar?

    Any thoughts on it?

    Joey wrote on February 14th, 2012
    • Sugar. It’s SUGAR.

      Leaf Eating Carnivore wrote on December 6th, 2012
  17. I have noticed that everytime a flu bug is around I will not catch it unless I compromise my diet. I eat a modified paleo diet consisting of raw veggies, minimal meat, and only sweet potatoes, quinoa, and organic brown rice. If I eat a cheat meal, and someone around me is sick I almost instantly (within 12-24 hours) get some mild flu like symptoms. The more antioxidants I take and the better my diet is the less I get sick. Great Post Mark!

    Jared Anderson wrote on March 15th, 2012
  18. Can anyone help me please? I am a chronic asthmatic with COPD. If I get caught in a drizzle I get very sick. Immune system is compromised from meds. I went to a nutritionist who said I should cut all sugar and fruits out of my diet. I recently got diagnosed with high blood pressure. So I started to add blue berries , dried cranberries etc to diet to combat the high blood pressure. Am I making a grave mistake?

    Fran wrote on July 24th, 2012
    • Yes. You are eating things that raise your blood glucose, and hence your insulin response, which can pretty directly initiate hypertension.

      As a start, read “Protein Power” and “The Protein Power LifePlan” for some good discussion about the common cause of the “Diseases of Civilization”.

      Listen to the nutritionist – dried fruits are just FRUITS without the H2O. At this point you’ve got bigger problems than missing added antioxidants.

      Leaf Eating Carnivore wrote on December 6th, 2012

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