These are the charges laid against sugar that suggest it does indeed suppress the immune system:

  • It damages the germ-killing ability of white blood cells for up to five hours after ingestion
  • It compromises the production of antibodies, proteins that combine with and inactivate foreign invaders in the body
  • It obstructs with the transport of vitamin C, one of the most important nutrients for all facets of immune function
  • It causes mineral imbalances and sometimes allergic reactions, both of which weaken the immune system
  • It neutralizes the action of essential fatty acids, making cells more permeable to invasion by allergens and microorganisms

Sugar Demystified


The simple sugar, glucose, is the energy of life. It is a simple monosaccharide found in plants. It is one of the three dietary monosaccharides, along with fructose and galactose that are absorbed directly into the bloodstream during digestion.


Fructose is a simple monosaccharide too that is found in many plants. However, without it's antidote fiber it overwhelms the liver and wreaks metabolic havoc. We need fiber to limit the absorption of fructose from the gut. Within a fibrous package, less sucrose (glucose and fructose) will be absorbed – and what is absorbed will occur over a more drawn out period of time. That gives the liver time to deal with fructose appropriately. And high fructose diets decrease HDL levels ("The Good Cholesterol"), while reducing the diameter and increasing the density of LDL ("The Bad Cholesterol") particles.


There is one other primary simple sugar beyond glucose and fructose, and that is galactose. It is found in milk as part of lactose (one glucose molecule and one galactose molecule). It doesn't have the same onerous metabolic action as fructose.


Sucrose is common table sugar. It's made up of one glucose molecule and one fructose molecule. White table sugar (sucrose) comes primarily from cane sugar. Whether it's white or brown or molasses, if it comes from the cane plant it's the same despite the advertising that it's natural. Brown sugar and molasses may have more nutrients than refined white sugar, but they are still missing fiber the one thing needed to counteract the potential negative consequences of eating fructose.

High Fructose Corn Syrup

High fructose corn syrup (HFCS) is just like table sugar and brown sugar in that it is one glucose molecule tied to one fructose molecule. Manufactures take corn syrup (which is two glucose molecules tied together) and through chemistry turn one of the glucose molecules into fructose. And there's usually no fiber with it in packaged and processed foods. The biggest problem with HFCS is that it's everywhere, a hidden ingredient in foods from bread to ketchup.

Natural Sugars

Honey, beet sugar, maple syrup and sorghum are all natural kinds of sugar, but like table sugar from the cane plant, they're half fructose and are generally devoid of fiber. They often contain more trace nutrients and minerals than refined white sugar and so are a somewhat a better choice.

Yes, fruit contains fructose

Fruit juice can be a problem. Eating whole fruit, on the other hand, is safe and nutritious. A bottle of juice from the supermarket or oranges run through a juicer contain fructose but without the fiber. The whole orange, however, contains fibre that limits the absorption of too much fructose.

Starch is a sugar

Starch is composed of strings of glucose molecules stuck together, and the body breaks them down to their simple form to be used as fuel. Starch is found in grains (rice, wheat, oats, barley, rye), starchy vegetables (potatoes, sweet corn, yams), and legumes (beans, soybeans, peas). They too have fibre to slow the absorption of the glucose.

Malt sugar

Of all the sweeteners this is the one natural product that is composed of two glucose molecules linked together. There's no fructose. It's not as sweet as cane sugar, but if you need to add a sweetener to drinks or foods, then the best choices are malted rice, malted barley, and malted wheat sweeteners.

Corn syrup

Without the manufacturer's trick to make it sweeter by changing half of it to fructose to form high fructose corn syrup corn syrup is composed only of glucose molecules and is a good choice for a sweetener for foods. This is not HFCS. Corn syrup is a natural and healthy option for sweetness.

The Answer To The Question

It is impossible (and shortsighted) to hone in on just a single factor such as sugar suppressing the immune system. It's also stress. It's too little exercise, or too much. It's lack of sleep. It's SAD (Seasonal Affective Disorder). Whatever contributes toward chronic inflammation, weight gain, excessive cortisol, and metabolic syndrome is most likely also contributing to a compromised immune system. Sugar plays a role, maybe even a big one, but it's not the only player yet it can make the problem – a weak immune system – even worse.

A Strong And Healthy Immune System Is The Answer

Avoiding chronic inflammation from a variety of sources, some of which are beyond our control, is the roundabout answer to whether sugar suppresses the immune system. If you are dealing with one or more of the above contributing factors then eliminating or at least decreasing sugar consumption will certainly help your immune system perform at a much higher level. When the immune system is not fighting chronic inflammation it is better able to turn its strength toward assaults from viruses and bacteria.