Vitamin C, a vitamin abundant in citrus fruits, is essential for healthy skin, bones, and joints. Without adequate vitamin C, you couldn’t synthesize collagen, the protein that provides support and strength and essentially holds everything in your body together. Vitamin C is also an antioxidant vitamin, one that helps neutralize harmful free radicals that can damage every cell in your body. It even helps to regenerate other antioxidant vitamins like vitamin E. In addition, vitamin C is important for healthy immune function. Humans, unlike most other animals, can’t make vitamin C and have to get it through diet. Therefore, it’s an essential nutrient.
Vitamin C already wears enough hats, but now a new study shows it has another possible benefit. Vitamin C mimics some of the health benefits of exercise, but before tossing out your exercise shoes and trading in your weights for a bottle of vitamin C, getting more vitamin C isn’t a replacement for exercise, but it does appear to improve blood vessel function in the same way exercise does. Note: This study was small, with only 15 subjects, and the participants were previously sedentary and overweight, so don’t automatically assume the same applies to fit, healthy people.
What the Study Using Doses of Vitamin C Showed
For three months, one group of sedentary, overweight participants walked briskly each day OR took a vitamin C supplement. By the end of the study, both the exercisers and the vitamin C group experienced improvements in endothelial function, the ease with which blood vessels dilate. Poor endothelial function is linked with poor cardiovascular health and high blood pressure. People who are sedentary and overweight or obese have higher levels of a protein that changes how blood vessels function, making them stiffer. This protein is called endothelin-1 or ET-1.
While this finding is interesting, the participants were taking relatively high doses of vitamin C, 500 milligrams daily, far more than the U.S. Dietary Reference Intake of 90 milligrams daily for men and 75 grams for women. It would be difficult to get this amount of vitamin C each day without taking a supplement. It’s also questionable as to whether your body can utilize that amount of vitamin C. According to some research, you can only process about 250 milligrams of vitamin C daily and the rest ends up in your urine. Of course, it’s also possible that lower doses of vitamin C might have similar benefits. Hopefully, they’ll look at this possibility in future studies.
The doses of vitamin C used in the study, 500 milligrams daily, is probably not high enough to cause significant side effects, although some people experience nausea or diarrhea at amounts this high. Higher doses of 2,000 milligrams or more increase the risk for kidney stones. Plus, iron can interact with some medications. Vitamin C also enhances iron absorption, making it beneficial for pre-menopausal females but possibly harmful to older women and men. Some studies show a link between high iron levels and diseases such as heart disease, type 2-diabetes, and Alzheimer’s disease. As important as iron is for carrying oxygen in your bloodstream, too much is harmful. Taking high doses of vitamin C can potentially throw your iron status out of balance.
What Foods Are High in Vitamin C?
When you think of vitamin C-rich foods, citrus fruits probably come to mind. No doubt, oranges, and grapefruits are a good source of vitamin C but so are kiwi fruit, strawberries, cantaloupe, green peppers, cauliflower, broccoli, collard greens, and Brussels sprouts. One thing to be aware of with regards to vitamin C – it’s a fragile vitamin that breaks down easily in the presence of heat. Storing vegetables for more than a few days and exposing them to high heat can destroy more than half of a food’s vitamin C. That’s why raw fruits and veggies are a better source of vitamin C than cooked ones.
Is vitamin C deficiency common? Although the classic vitamin C deficiency disease, scurvy, is uncommon, according to a study published in the American Journal of Public Health, sub-optimal vitamin C levels may affect up to 20% of the population. Smoking and not eating 5 or more servings of fruits and vegetables daily are the biggest risk factors for vitamin C deficiency. Even if you are eating fresh produce, you may be destroying a significant portion of vitamin C during the cooking process.
Should you take a vitamin C supplement? One of the dangers of taking high doses of vitamin C is its interaction with iron. According to Dr. Victor Herbert, professor of medicine at the Mount Sinai School of Medicine in New York, vitamin C in high doses may actually promote the formation of damaging free radicals by activating iron already stored in your body. This shows how too much of a good thing may have harmful effects. Vitamin C protects against the formation of free radicals but can actually increase their production at high levels. So, diet is the way to go for meeting your vitamin C requirements.
Because exposure to heat destroys some of the natural vitamin C in foods, eat a portion of your vitamin C rich foods in their uncooked form. Most importantly, make sure you’re getting your 5+ fruits and veggies daily.
The Bottom Line
Despite this encouraging study, vitamin C is not a replacement for exercise. Where it may have benefits is for people who can’t exercise due to disabilities. Remember, exercise does far more than improving blood vessel function. Vitamin C can’t match the long list of health benefits exercise offers, but it may have heart-health benefits for people who are unable to exercise. Make sure you’re getting enough vitamin C but do it by eating more raw fruits and vegetables.
The Journal of Biological Chemistry, 282, 15506-15515. May 25, 2007.
Dr. Andrew Weil. “Facts on Vitamin C”
Berkeley Wellness. The Good and Bad of Iron”
Flipper.Dif.Org. “THE FENTON REACTION: pro-oxidant role of vitamin C”
Science Daily. “Vitamin C: The Exercise Replacement?” September 4, 2015.
Am J Public Health. 2004 May; 94(5): 870-875.
The New York Times. “Taking Too Much Vitamin C Can Be Dangerous, Study Finds”
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