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Six Facts about Vitamin C

By January 2, 2018May 21st, 2020Health, Nutrition
Fruit high in Vitamin C

Vitamin C is the aspirin of the dietary supplement industry, but just like the seemingly benign pain-killer, there are some important health considerations if you take this synthetic nutrient.


Vitamin C products are the most successful business venture in the multi-billion-dollar dietary supplement industry.

What most people know as “vitamin C” is actually industrially produced synthetic ascorbic acid —made by drug companies. This chemical form of vitamin C is widely used as both a nutritional supplement and as a preservative in the food, pharmaceutical and animal feed sectors. Much of the synthetic vitamin C in the world is sold to health-conscious consumers.

Synthetic supplements have lower bioavailability than real foods, which means you can’t absorb them nearly as well. Studies have shown that vitamin C from food is absorbed 35 percent better and excreted more slowly than synthetic vitamin C. In addition, the body attempts to eliminate synthetic vitamin C, so in some circumstances taking higher doses may actually cause excess loss.

Conversely, real vitamin C as found in real food is accompanied by a complex of many other naturally occurring phytonutrients. As such, the body’s vitamin C requirements are best met from foods rich in this nutrient.

Natural vitamin C is required for growth and repair of tissues in all parts of your body. It plays an important role in the production of collagen and certain neurotransmitters, and is valuable in healing and protein metabolism. A powerful antioxidant, it impacts immune function, and its presence in food can influence various conditions such as cancer, cardiovascular disease, high blood pressure, asthma, osteoarthritis, macular degeneration and cataracts, and others.

Nature provides plenty of real vitamin C in foods. Broccoli, Brussels sprouts, kale, acerola and other foods are particularly rich sources not only of vitamin C but thousands of other phytonutrients associated with vitamin C. You can also find large amounts of vitamin C in animal sources, especially the adrenal and thymus glands, brain, bone marrow, pancreas, liver and kidney (even the eyes though few people eat these). While most people don’t eat organ meats, many unfortunately also avoid the most vitamin C-rich portions of plant foods: the white pulp of peppers and citrus (including the skins).

Nutritional need for vitamin C varies with age, sex and state of health for all individuals, with higher levels required by smokers and others with special requirements. The new daily value (DV) for vitamin C is 90 mg for adults and children age 4 and older.

Because this nutrient generates so much money throughout the industry, the negative potential effects of improper vitamin C intake are not usually brought to light. Here are six of them:

1. Synthetic vitamin C is ineffective. From the common cold and cancer, to heart disease and overall mortality, scientific studies continue to show synthetic vitamin C supplements have little to no benefits. Furthermore, evidence remains mixed regarding the purported effect of synthetic vitamin C on overall health, sports performance, and recovery from muscle damage.

2. Most vitamin C is fake — and it’s made from sugar. Almost all vitamin C supplements on the marketplace are synthetic. Since glucose and vitamin C have similar chemical structures, it’s easy and cheap to produce fake vitamin C from sugar, typically using corn. A look at the label is all that’s needed to tell whether vitamin C is naturally sourced: Since even the foods richest in vitamin C don’t contain very high concentrations, doses above 300 mg in a supplement almost always indicate a synthetic source.

3. Vitamin C absorption is impaired by carbohydrates. In the intestines, vitamin C absorption competes with glucose for absorption. Ironically, many vitamin C products and food products with added vitamin C also contain added sugar. So consuming junk food could result in lower absorption rates for vitamin C.

4. High doses may produce serious side effects. A variety of side effects are attributed to vitamin C doses of 500-1,000 mg. Popular doses can produce harmful free radicals when they react with iron in the body or other dietary supplements. In addition, higher doses of synthetic vitamin C themselves can become pro-oxidants. Published studies demonstrate that 1000 mg/day of synthetic vitamin C can interfere with cell signaling in working muscles. This blocks the body’s ability to adapt to training, reducing endurance performance gains. Other side effects may include heartburn, diarrhea, nausea, abdominal bloating, risk of forming kidney stones and inhibition of vitamin B12 function. In addition, synthetic vitamin C can adversely react with many over-the-counter and prescription medications.

5. Less is more. Up to 200 mg of natural vitamin C may be contained in a meal of fresh fruits and vegetables. In this natural presentation and dosage, almost all of the vitamin can be absorbed. However, our bodies can utilize at most 500 mg of a vitamin C supplement leading to reductions of over 50 percent in the absorption rate of higher doses. Studies show levels above this amount can have unhealthy effects. Even Linus Pauling, a proponent of very high dose synthetic vitamin C, said in 1974 that “the first 250 mg is more important than any later 250 mg. The first 250 mg leads you up to the level where the blood is saturated.”

6. Real food works best. Studies have long shown that people whose diets were rich in real foods naturally high in vitamin C — typically around 200 mg per day — have a lower risk of heart disease, certain cancers and other diseases. Vitamin C in foods have not been shown to cause any of the problems of synthetic supplement use. In addition, food sources of vitamin C have not been shown to cause adverse reactions to medications.

The portrayal of vitamin C as a safe and effective supplement is a broad generalization promoted by an industry that is making billions off high-dose synthetic products. Although we all need adequate amounts of vitamin C for good health, this nutrient is best obtained as nature intended — from real, natural foods.