Supplements: How Much Should I Take?
People have been preaching the merits of moderation since the time of the early Greeks, most likely even before that. For all we know, prehuman prophets may have been telling their followers to practice moderation.
But then, as now, probably no one listened.
In a healthy person, dietary moderation makes a lot of sense. Eat a little of all types of food. Well, it's not essential to include fast food, highly processed snack foods, supersweet or supersalty foods. But in a healthy person, occasional consumption of such unhealthy foods probably causes no harm.
In a healthy person who eats a good diet and gets enough sunshine, there's probably no reason to add vitamins and other supplements. (I say probably a lot because what we don't know is much more than what we do know, and research in the future could turn today's "truths" upside down.)
But when you have a chronic disease like diabetes, the prescription changes. If you find that carbohydrate foods make your blood glucose (BG) levels soar, then moderation is no longer enough. If you want good control, you may have to cut way back on such foods, especially those with a high glycemic index.
So too, if you find that eating fats makes your BG levels stay high for hours after you eat, you may have to limit your fat intake as well as your intake of carbohydrates.
And if your diet has become limited in various ways, it is prudent to supplement with at least a basic multivitamin. If you live in a northern climate and don't get much sunshine, extra vitamin D would be a good thing. If you don't eat much fish, you might want to add some fish oils to your diet. If you're limiting dairy, extra calcium makes sense. If you've cut back on citrus fruits because of their high sugar content and if you don't eat a lot of other vitamin-C-containing foods like cabbage, extra vitamin C would be prudent. If you're vegan, it's important to add vitamin B12, which is found primarily in meat, dairy foods, and eggs.
But when it comes to supplements, I think moderation should be the key as it is with other things in your life. If a little of some supplement seems to help, that doesn't mean a lot will be as beneficial. Sometimes too much of a "beneficial" supplement can cause harm.
As one example, fish oils are healthy sources of omega-3 fatty acids, and many studies have shown that consumption of fish oils improves health in many ways. But not all reports are positive. For example, a recent study reported that DHA, one of the long-chain omega-3 fatty acids that are said to be beneficial, was linked to increased colon cancer in mice.
Because DHA is anti-inflammatory, the researchers expected it to decrease cancer rates in the mice, which were prone to inflammation. Instead, it did the opposite. A similar effect was found some time ago with vitamin A and lung cancer. Researchers expected to see less lung cancer in smokers taking vitamin A supplements because smokers whose diets included a lot of vitamin-A-rich foods had less lung cancer. Instead, cancer rates increased.
Does this mouse study of fish oils mean people should avoid DHA and maybe all fish oils? Not at all. As the researchers point out, many drugs, nutrients, and normal body constituents show "bell curve" effects, meaning that either too little or too much may be harmful. A technical term for nonlinear effects of some treatment, with benefit in a particular range and harm with either too much or too little, is hormesis.
One example of this we're all familiar with is BG levels. Too high is bad. But too low is also bad. As in the story of the three bears, we need to keep our BG levels "just right," in the middle of the curve. The same is true of exercise. Being a couch potato is not healthy. But neither is breaking up rocks for 18 hours a day, which leads to exhaustion and wears out the joints. Moderate exercise is healthy.
Most Americans have diets that are deficient in omega-3 fatty acids. There is evidence that these people would benefit from fish oil supplements. But others, especially people who eat a lot of fatty fish, probably get enough in their diet, and for them supplementing may not be a good idea.
The recent studies of DHA were done in mice, and mouse studies don't always translate into effects in humans. Also, "linked to" is not the same as "causes." Nevertheless, it suggests that one shouldn't go overboard with fish oil.
Another example of the need for moderation is a study showing that inflammation can be healing. Many of us think that inflammation is bad, and antioxidants are the fad supplements of our time. But this study shows that inflammation helps to heal damaged muscle tissue.
"For wounds to heal, we need controlled inflammation, not too much, and not too little," said the editor-in-chief of the FASEB Journal, in which the research was published. The Three Bears again.
Americans are told over and over again that antioxidants are needed for health, and yes, some antioxidants are. But going overboard with antioxidant supplements may not be a good idea. One advantage of getting antioxidants and vitamins from food is that there's a limit to how much we can eat. But we can easily overdose with supplements.
A third example is calcium supplements. We're all told we need extra calcium, especially if we're older women. But a study published this summer suggested that too much calcium supplementation can increase the risk of heart attack. Previous studies had shown that excess calcium in food presented no risk.
This study suggested that supplementing with more than 805 mg per day increased cardiac risk 30%, but lower levels did not. Postmenopausal women are usually advised to take 1200 mg per day, or even more.
Does this mean we should all chuck our calcium supplements? Again, probably not. But if we can get our calcium from food instead of pills, we're better off. Canned fish that includes the bones and dairy products are high in calcium. Yogurt is a good choice for dairy because the bacteria consume much of the sugar in the whey.
All three of these recent studies are consistent in suggesting that when you decide that because of your diabetes or your age you are probably deficient in some nutrient, then by all means take a supplement.