How Sugar Competes With Vitamin C & Sidelines Vitamin D to Take Down Your Immune System

You’re probably aware that sugar isn’t that great for your health. Most people only have a vague idea why – usually revolving around excess calories and weight gain. Sugar’s effects on the body are far more sinister, with links to cancer, diabetes, Alzheimer’s disease and many more modern illnesses (1). Its ability to derail our system from up-taking key vitamins like vitamin A and vitamin D seriously impacts our immune system, essentially taking it down, along with a host of other key metabolic functions that are the difference between health and illness. Here’s what you need to know.

Vitamin C & Vitamin D: Immune System Superstars

Our bodies run on chemistry and some nutrients are make or break for our health. Sugar sidelines 2 very key players for our immune system and overall well-being: vitamin C and vitamin D.

Vitamin C is a water-soluble nutrient with many vital functions in your body. It helps strengthen your immune system, aids collagen production and wound healing, and acts as an antioxidant to protect your cells from free radical damage (aka protects against cancer). Unlike other animals, humans cannot synthesize vitamin C on their own. Therefore, you must get enough of it from foods or supplements to maintain good health.

The vitamin is especially helpful for immune health, as it supports your immune system’s cellular function. In fact, vitamin C supplements may help prevent infection, while a deficiency of the vitamin appears to make you more susceptible to infection (2). In today’s world, being susceptible to infection isn’t something any of us want. Instead, we would rather be impervious!

Vitamin D is completely different than most other vitamins. In fact, it’s a steroid hormone produced from cholesterol when your skin is exposed to the sun. For this reason, vitamin D is often referred to as “the sunshine vitamin.” However, sun exposure rarely provides adequate vitamin D in today’s hide indoors and slather on sunblock culture, making it necessary to obtain vitamin D from supplements or your diet. Around 41.6% of the U.S. population is deficient (3).

Most people think of vitamin D as the bone health vitamin but it does far more than protect or strengthen our bones. For example, it promotes the absorption of calcium and phosphorus from your gut. But scientists have recently discovered that it also plays roles in other areas of health, such as immune function and protection against cancer (4). Studies indicate that people with low vitamin D levels have a much greater risk of heart disease, diabetes (types 1 and 2), cancer, dementia, and autoimmune diseases like multiple sclerosis. Finally, vitamin D deficiency is linked to a reduced life expectancy (5).

All this makes vitamin D and vitamin C rather important, wouldn’t you agree?

And yet we are actively bombarding our bodies with the very molecule that sidelines these two essential vitamins when we eat sugar.

young black woman covered with blanket blowing nose
Photo by Andrea Piacquadio on

Sugar’s Ability to Mimic Vitamin C

We are chemical beings and what we eat and drink matters. Our bodies evolved to eat real foods, not modern processed ones like sugar. Two hundred years ago, the average American ate only 2 pounds of sugar a year. In 1970, we ate 123 pounds of sugar per year. Today, the average American consumes almost 152 pounds of sugar in one year. This is equal to 3 pounds (or 6 cups) of sugar consumed in one week! See How Much Sugar Do You Eat? You May Be Surprised! published by the Dept. of Health and Human Services.

All this sugar plays havoc on our bodies. What’s more, its chemical structure makes it perfect for mimicking vitamin C to get into cells in its place.

Visualize it this way: Remember the children’s toy of variously shaped blocks and matching holes? The toddler’s task is to match the right shape to the proper hole. Furthering the analogy, if you have two blocks identical except for color, they’ll still fit through the same matching hole. That’s an apt analogy for how our body absorbs and reacts to the molecules and chemicals that make up our food. Everything has a chemical structure and its looking to dock or react with receptors in our body, be they cell walls or enzymes.

Vitamin C and sugar share similar chemical structures and use the same glucose transporters to enter cells. Research has shown that high levels of glucose (whether in the intestines or in the blood) can slow down or limit the absorption of vitamin C by our bodies (6). Basically, vitamin C serves essential health purposes that get “blocked” when sugar steals the glucose transporters away from it. Eat sugar and your immune system gets “hijacked” by the sugar, leaving vitamin C without a ride and a way for your body to absorb and use it. As a result, your immune system gets impaired.

Further, sugar creates free radicals – those oxidizing chemicals that lead to cancer. Vitamin C neutralizes free radicals – but only when absorbed by your body. Sugar consumption not only blocks vitamin C from doing its job, it creates even more free radicals in your body in a one-two punch. It’s akin to criminals taking over a police station, kicking the cops to the curb, and inviting their friends over to the neighborhood to riot until there’s nothing left to wreck.

Sugar Sidelines Vitamin D

It’s no secret that vitamin D deficiency is a big problem these days (especially for those living far from the equator), but lack of sun exposure isn’t the only cause. Excessive sugar intake (especially in the form of fructose) may actually exacerbate vitamin D deficiency (7).

How does it work? Researchers have discovered that a high intake of fructose can increase the expression of an enzyme responsible for degrading vitamin D, while also decreasing the expression of an enzyme that helps synthesize vitamin D. As a result, fructose can enhance the breakdown of vitamin D in the kidneys while also impairing the body’s ability to synthesize it. The result is a reduction in vitamin D levels, and the potential for the harmful effects of deficiency to manifest (such as greater susceptibility to infection, higher risk of autoimmunity, increased rates of certain cancers, and overall lower immune function).  When we’re eating 152 pounds of sugar a year, no wonder so many people in Western countries are deficient in vitamin D!

Supplemental Problems

Many health-conscious people turn to vitamin supplements to boost their vitamin A and D levels. However, they may not realize that many of those vitamins come dosed with sugar. Read your labels carefully and you might be surprised by the amount of sugar included in each dose. For reference, 3 grams of sugar is equivalent to one packet of sugar in your tea or coffee. When you take vitamins, especially the sweet gummy ones, you’re usually taking this much or more of additional sugar.

Great, now you’ve delivered sugar into your system where it will take vitamin C’s glucose transports, preventing its absorption. Meanwhile, you’ll also deliver a dose of sugar to degrade vitamin D as well and limit your body’s ability to synthesize it. How helpful are those supplements looking now?

But it doesn’t stop there.

We drink a lot of milk, often fortified with vitamins C and D. Hooray! But wait, the typical one cup serving of milk contains 12 grams of sugar!

Face palm.

So what are we supposed to do to keep our immune systems healthy?

Real Food = Real Health

We are chemical beings and what we eat matters. Our bodies evolved eating real foods – things like fresh meat, seafood and whole foods such as fresh fruit, vegetables, whole grains, pulses, legumes, nuts, seeds and tubers. We didn’t evolve on processed foods, refined carbohydrates and the nutrition-less foods of the modern Western diet – as the explosion in modern diet-related health problems attests. There is no magic pill that will allow us to eat whatever we want without facing health consequences. The only way to good health – and a strong immune system – is to eat properly. Period.

Want to up your immune game? Eat real foods high in vitamins and other essential minerals. Limit your intake of non-whole foods like frozen foods, heat and serve meals, take-out, fast food, junk food, refined carb meals, and sugary snacks and deserts. We need to get back to the place where we ate 2 pounds of sugar a year, not a week. That’s when we’ll see our health outcomes turn from disastrous to fantastic.

Join the real food revolution today. Your health and well-being will thank you.

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