Q. It seems like everyone I know is doing a cleanse or detox diet. Is there any merit to them?
A. As my readers know, I'm open to a number of non-traditional treatments. Some have been studied scientifically and found to be valuable -- like tai chi for fibromyalgia. Others haven't been fully studied but appear to have no adverse effects, and some people swear by them -- such as acupressure for the nausea caused by chemotherapy. I'm open-minded, yet skeptical, about any proposed treatment -- mainstream or complementary -- until it's been shown to be of value in scientific studies.
Which brings us to cleanse or detox diets. You've probably heard of the "Master Cleanse." For days, you consume only a concoction made of spring water, organic maple syrup, freshly squeezed organic lemon juice and a pinch of cayenne pepper. Not all detox diets are that extreme, but many do require at least 24 hours of a strict liquid diet.
But what exactly does it mean to "detoxify"? And do these diets really hold the key to physical and spiritual rejuvenation?
The word "detoxification" describes any type of therapy that removes potentially damaging toxins from the body. Pesticides are an example.
The idea behind detox diets is that the buildup of toxins in our bodies decreases immunity, leads to chronic disease, decreases energy and slows metabolism. Detox diets claim to cleanse the body of this toxic waste. As toxins are flushed out, so the theory goes, the body functions better and metabolism returns to normal.
I'm sympathetic to this idea. Surely, in the post-industrial age we have added many chemicals into our environment -- chemicals that none of our species, going back 40,000 years, had ever been exposed to. It's not unreasonable to think that some of these chemicals might be damaging our health, and that anything that removes them from our body might therefore be beneficial.
But there's no evidence that detox diets actually remove toxins from our bodies, prevent chronic disease or improve overall health. What's more, detox diets can be expensive and can cause unpleasant side effects such as decreased energy, lightheadedness, headaches and nausea.
Before you go on a detox diet, consider this: Your body's own organs, particularly the liver, are part of a natural detoxification system. They convert toxins into non-toxic substances that your body excretes.
Specific foods and food groups are especially good at supporting our natural detoxification system. At the top of the list are cruciferous vegetables, such as broccoli, cabbage, watercress and Brussels sprouts. Other foods on the list include garlic, leeks and onions, turmeric and citrus peel.
If you're in good health, a brief detox diet probably won't hurt. But avoid one completely if you are nursing or pregnant, young, elderly or have a medical condition.
I support my body's natural detoxification system by eating a well-balanced, plant-rich diet that includes plenty of detox-supporting foods. After all, why drink broccoli when you can just eat it?
• Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com.