The benefits of vitamin C for treating or preventing colds has been hotly debated for decades. The evidence now suggests that supplementing with vitamin C does not reduce the risk of catching a cold, according to a 2013 review of the scientific literature that included 29 trials with more than 11,000 people. However, there is some evidence that vitamin C does have some benefits. The researchers found that taking vitamin C regularly may help you bounce back from a cold a bit faster and possibly reduce the severity of a cold when you do get one.
“Supplemental vitamin C may lessen the duration and symptoms of the common cold because of its immune-enhancing effects,” says registered dietitian Lisa Fischer, MS, RDN. “It’s not like if you take vitamin C, it’s going cure your cold, but it makes the body more capable of fighting off the virus once you have it.”
In the review, adults who took vitamin C regularly had an 8% reduction in the duration of colds compared with people who did not take it. However, taking vitamin C as soon as symptoms started did not seem to make a difference.
In addition to boosting the immune system, Fischer says vitamin C helps repair and regenerate tissue, protect against heart disease and certain cancers, aid in iron absorption, decrease LDL cholesterol (the bad kind), and plays a role in building collagen. It’s also an antioxidant that helps protect cells and DNA against free radicals and other harmful agents that can cause damage to cells. To reap the greatest benefits of supplemental vitamin C, Fischer says it’s best to make it a daily habit. “Any of the research that supports vitamin C says it’s best to take it continuously or consistently, rather than right before you feel like you’re getting sick,” says Fischer, who sees clients at The UltraWellness Center in Lenox, Massachusetts.
But don’t rush to order vitamin C pills just yet, as it’s better to get your daily dose from vitamin C-rich foods. According to Fischer, the additional phytonutrients and phytochemicals that foods contain aid in cancer prevention and fighting other diseases. The best dietary sources of vitamin C may surprise you. “A lot of people assume that vitamin C is found in fruit like oranges, but actually, some of the top sources are vegetables such as bell peppers, broccoli, brussels sprouts, cauliflower, and squash,” says Fischer. “The best sources from fruit would be papaya, strawberry, pineapple, orange, kiwi, and cantaloupe.” (Here are 10 vitamin C-rich foods other than oranges.)
The only people who should rush to pop a pill, Fischer says, are those who are deficient in vitamin C (here are the silent signs you might be low on key vitamins). If you’re considering supplementation, studies show that consuming between 250 and 1,000 mg of vitamin C a day is considered safe, but more than that could lead to potential gastrointestinal symptoms such as diarrhea and gastritis and other issues. “The higher doses of vitamin C, which would be considered anything above 1,000 mg or one gram, can interfere with the effects of blooding thinning medications including warfarin (Coumadin), oral contraceptives, barbiturates, aspirin, and acetaminophen (Tylenol), as well as chemotherapy drugs,” Fischer says.
Before taking vitamin C supplements, talk to your doctor to suss out any problematic drug interactions and determine the dosage that’s right for you.