My mother puts a lot of stock in vitamin C. She keeps a bottle of the chewable variety in her kitchen drawer—not the junk drawer with its litter of take-out menus and thumbtacks, but the high-traffic silverware one. As long as I can remember, she’d press a grainy wafer into my palm at the first sign of a sniffle or sneeze.
But lately I’ve wondered if she hasn’t been hoodwinked. The last few years of research have introduced many questions about the old nutritional standby. Which form is best: powder or liquid? Tablet or capsule? Ester-C or ascorbyl palmitate? Confusion has also erupted over how much we should take; at various times, daily recommendations have ranged from 60 milligrams to 18,000. Experts have even conceded that vitamin C does diddly to stave off colds. Sure, high doses of the vitamin may shave one miserable day off any given bout, but that’s cold comfort if you’re banking on a way to avoid the sniffles altogether.
Through it all Mom has stayed the course, calmly munching her daily C tablet. She isn’t going to let a bunch of naysayer scientists derail her convictions, she says. And now it looks like she might really be on to something. New studies suggest vitamin C may ward off heart disease and cataracts, as well as certain cancers. Plus, there’s interesting news on how much is needed and how best to get it. (As Mom intuited, diet may not be enough.) Read on; then start making room in your silverware drawer.
Protect Your Heart
Evidence for vitamin C’s power to thwart heart disease comes from the Nurses’ Health Study at Harvard University, where researchers followed the diets of more than 85,000 women for 16 years. They found that women who took in the most vitamin C were 27 percent less likely to suffer a heart attack or die from heart disease than those who consumed the least.
The kicker was that those who got their C from food alone didn’t reap the benefits. “Even women who were getting more than three times the RDA from the foods they ate weren’t protected,” says Jane Higdon, a nutritionist at the Linus Pauling Institute at Oregon State University, in Corvallis, and author of An Evidence-Based Approach to Vitamins and Minerals.
Exactly how much C do we need to protect our hearts, and what portion of that should come from a pill? Although the RDA was bumped up three years ago, many experts believe it’s still too low: At 90 milligrams a day for men and 75 for women, you won’t get scurvy, but you won’t get C’s other perks, either. The body needs at least 400 mg a day in order for the vitamin to saturate tissue and plasma and exert a positive effect. Indeed, most studies trumpeting vitamin C’s benefits rely on doses up to six times higher than the RDA.
The problem is that even if you down your five or more servings of fruits and vegetables a day, you’re still likely to get less than the optimal daily dose. C-fortified juices can help, but to be on the safe side, many experts recommend filling the void with either a supplement or a multivitamin that contains at least 200 mg of C.
And it doesn’t matter which form of it you take. The body doesn’t play favorites when it comes to vitamin C supplements, says Higdon. “Take whatever is economical and that you tolerate well,” she advises.
Stave Off Cancer
So far, some of the best evidence for C’s cancer-fighting power is on the lung front. Most smokers have less vitamin C circulating in their bloodstream than nonsmokers do, which is why the RDA for smokers is now 35 mg higher than for nonsmokers. Indeed, test tube studies have already demonstrated that vitamin C squelches free radicals produced by cigarette smoke. And in a recent study at the University of California at Berkeley, nonsmokers who were exposed to the smoke of at least nine cigarettes a day, and who also took daily vitamin C, showed a significant decrease in levels of a particular biomarker of cellular damage related to cigarette smoke.
Several large epidemiological studies have also shown that people who get a lot of C have lower rates of stomach cancer, possibly because C seems to quell Helicobacter pylori, the bacteria that triggers ulcers and has been linked to the cancer.
The research about vitamin C and eyes is particularly stunning. In two studies, volunteers who took in more than 300 mg of vitamin C a day cut their risk of cataracts by up to 75 percent.
Why? Most likely it’s that C’s antioxidant activity counteracts the bad effects of the sun. These days, most people know it’s important to protect their skin when they’re outside. But it’s easy to forget that our eyes are also assaulted by ultraviolet rays, which generate damaging free radicals. Sunglasses may help, but a lifetime of inconsistent use may still add up to cataracts, says Higdon. Vitamin C can’t undo the damage, but it can prevent cataracts from developing in the first place.
The bottom line? The argument for vitamin C may be changing, but it’s not diminishing in force. In fact, last summer the vitamin C gurus at the Linus Pauling Institute upped their daily dose recommendation from 200 to 400 mg. “I’m sure Linus would have advocated the switch,” says Higdon.
- What it is: Vitamin C is an essential nutrient found primarily in fruits and vegetables.
- Dosage: The RDA is only 90 milligrams for men and 75 for women, but studies show that if you want all the benefits C potentially has to offer—protection against heart disease, lung cancer, cataracts, and more—you need at least 400 mg a day. Five (or more) servings a day of fruits and vegetables deliver about half that; you can get the rest with either a daily supplement or a multivitamin that contains at least 200 mg of C. Don’t worry about what form to take; they’re all equally effective, say experts.
- Risks: Vitamin C is one of the safest supplements on the market. The chief result of overdoing it is diarrhea. Some evidence hints that high doses may spur the formation of kidney stones. To be on the safe side, take less than the upper tolerable intake level of 2,000 mg a day.
By Catherine Guthrie