DEAR DOCTOR K: I'm a healthy woman in my 40s. Should I take extra folic acid to boost my immune system?
DEAR READER: Folic acid is, essentially, a vitamin. We all need vitamins. Indeed, the word "vitamin" was coined to refer to a substance that was essential to human life. The natural form of folic acid, folate, occurs in some foods, including vegetables, fruits, and dried beans and peas.
DEAR DOCTOR K: I've seen many product labels that claim to boost immunity. Could they really help? Or should I be skeptical?
DEAR READER: Your immune system does a remarkable job of protecting you from bacteria, viruses and other microbes that can cause disease, suffering, even death. So it seems logical to want to give your immune system a boost. But the concept of boosting immunity actually makes little sense scientifically.
DEAR DOCTOR K: I've read a lot about vitamin D deficiency in the news. How much do I need? Where can I get it?
DEAR READER: I try to make things clear, but the value of vitamin D supplements is complicated. Here it is in a nutshell.
DEAR DOCTOR K: What is an antioxidant? Should I be taking an antioxidant supplement?
DEAR READER: Something terrible often happens to medical scientists: A beautiful theory is murdered by a brutal gang of facts. The theory that vitamin pills with antioxidant powers — primarily vitamins A, C and E — could slow aging, fend off heart disease, improve flagging vision and curb cancer was beautiful and very plausible. As a result, some doctors urged their patients to take such vitamin pills daily.
DEAR DOCTOR K: My mom always told me to take vitamin C and not to drink milk when I had a cold. Is this true or just an old wives' tale?
DEAR READER: The idea that vitamin C supplements might prevent the common cold, or shorten the duration and reduce its symptoms, was popularized by the biochemist Linus Pauling. Randomized controlled trials involving thousands of people were conducted. My interpretation of the results of those studies is that they showed no evidence that vitamin C supplements reduced the duration or severity of the common cold. There was weak evidence that they might reduce the risk of catching it.
DEAR DOCTOR K: I need to get more calcium, and I'd like it to come from foods rather than supplements. I'm a vegan, so dairy products aren't an option for me.
DEAR READER: When most people think of food sources of calcium, they think of milk and cheese. Vegans can't eat food that comes from animals, so those sources of calcium aren't available to you. But getting calcium from food sources is becoming easier for vegans. There are many vegan foods that are naturally rich in calcium, and more foods than ever are fortified with calcium, including some cereals and orange juices.
DEAR DOCTOR K: Many herbs, vitamins and supplements claim to boost energy. Do any of them actually work?
DEAR READER: Unfortunately, there is not much scientific evidence to support the claims. Here is my best current assessment of the published evidence:
DEAR DOCTOR K: I take vitamin and mineral supplements. Do I need to worry about getting too much of certain nutrients?
DEAR READER: Many people take individual vitamin and mineral supplements in addition to a powerful multivitamin. But ingesting too much of certain micronutrients can be dangerous.
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Dr. Anthony Komaroff is a practicing physician, Professor of Medicine at Harvard Medical School, and Editor in Chief of Harvard Health Publications. Learn more »
Harvard Health Publications is the publishing division of Harvard Medical School, providing the general public with authoritative, trustworthy, and accessible health information. Learn more »
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