Part 2 - Sugar, Immunity & Glycemic Control

When we eat a meal, blood sugar levels rise, peaking 1-2h postprandially (post-eating) & normalizing by 3-4h postprandially. Sugar in the blood is problematic so insulin rises after eating to help shunt glucose out of the blood & into the tissues.

Much of what we know about sugar & immunity comes from looking at diabetes - a condition where hyperglycemia (too much sugar in the blood) is a defining feature. Sustained high blood glucose (for example in poorly controlled diabetes) can cause a dysfunction of many components of the immune system increasing risk for several inflammatory conditions, more frequent infections, complications & reduced recovery.⠀

There are numerous mechanism by which hyperglycemia has negative effects on immunity:

1️⃣Enhanced virulence of infectious germs by changing molecules on our cells surfaces ex. Advanced Glycemic End (AGEs) products: sugars stick on our own proteins disrupting their function & trigger unruly inflammation.

2️⃣Dicarbonyls are breakdown products of glucose that interfere with infection-controlling antimicrobial immune molecules called β-defensins. Beta Defensins are small proteins that function in antimicrobial defense by penetrating a microbe's cell membrane and cause microbial death in a manner similar to that of antibiotics

3️⃣Immune responses are energetically costly & have varying needs for different metabolic fuels (proteins, carbs & fats) depending on what function they are carrying out. Blood sugar needs to be able to get into immune cells so they can carry out their function. But if insulin control of blood sugar is not working properly, then energy can’t get from blood to cells & immunity can be compromised.

4️⃣Increased oxidative stress, a disease-causing mechanism that links elevated blood sugar & insulin resistance with the dysfunction of certain crucial protective mechanisms in the body, which over time leads to inflammatory disease e.g. heart disease.

These are just SOME of the problematic mechanisms at play with poor glycemic control. But what if you are not diabetic? Glycemic control is still really important to overall health. But before you say ‘sugar is bad’ consider that this doesn't make sense unless you also consider what your overall diet looks like. Context matters.

PART 1: Does Sugar Really Hurt Our Immunity?

A much- requested post so I am going to split it into two. #Sugar might be the nutritional demon du jour but there is a lot more to the story.

Now I don’t know about you but I don’t know anyone who eats just sugar. Generally, we eat food & this is your first clue: diet is the sum of its parts. If I eat a tablespoon of white sugar right now is it bad for me? Will it harm my immune system? Without looking in context of my overall diet, it would be impossible to say.⠀

Sugar comes to us not just by way of what we traditionally think of as white table sugar, but from any starchy carbohydrate food which gets broken down into simple sugar molecules in our digestive tracts. This is the second critical point: carbohydrates, like other macronutrients, cannot simply be classified as good or bad despite whatever fad diet comes about: context matters.

The idea that sugar can weaken the immune system came about several decades ago when studies showed that neutrophils (a type of immune cell) in test tubes were less good at doing their job in the 5hours after a person had eaten sugary foods. But this hasn't been replicated with direct scientific evidence to suggest that consuming sugar will directly weaken your immune system. Because context matters & (to reiterate) diet is the sum of its parts.

BUT sugary foods ARE easy to eat, hitting that bliss point, making them easy to overconsume. We do know that consistently eating TOO MUCH can adversely impact immune function.

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Sugary foods also tend to be LOW IN fiber & phytonutrients (a broad name for a wide variety of compounds produced by plants. Like:antioxidants, flavonoids, phytochemicals, flavones, isoflavones, catechins, anthocyanidins, isothiocyanates, carotenoids, allyl sulfides, polyphenols), which are key to nourishing your immune system & keeping it functioning well for the long game. Too many sugary foods can crowd out the good stuff.

Emerging research into the microbiota that support your immune system also hints that eating too much sugar, in lieu of healthier foods, might have a negative impact on immunity.⠀⠀⠀⠀

But you know this is not the end of the story. More to come in my next post. Let us know any questions you have in the comments below!