We have found that a diet that provides these nutrients in the form of intact foods is more effective for disease prevention than when the nutrients are taken by themselves. The reasons for this are not clear. Among the possible explanations are that other compounds contained in fresh fruits and vegetables, such as the so called "phytochemicals," are the beneficial components. Also, taking a large dose of a particular nutrient may not provide the same benefits that taking smaller doses over an extended period of time might.
There is no single "magic bullet" in regard to micronutrient supplementation. We should continue to counsel everyone to follow a high fruit and vegetable diet and one that is low in animal fat and one that is high in fiber.
That's right. Your patient, Joel, would have been better off simply increasing her daily intake of fruits and vegetables.
Are Supplements Ever Useful?
Single nutrient supplementation is beneficial for certain groups of people. For example, modest supplementation with vitamin E appears to lessen arteriosclerotic disease in patients who are prone to that condition. But, does all this evidence mean that carotenoid research and supplementation is a dead issue?
One of the things that scientists in this area are trying to figure out is exactly what did happen in these beta-carotene trials to produce the harmful effect that was seen. There is preliminary data from the Physician's Health Study that men who have already experienced an episode of cardiovascular disease (i.e., heart attack, coronary artery bypass, etc.) were in fact protected against a second cardiovascular event if they were taking beta-carotene. So the entire story is not yet in and trials continue to go on using beta-carotene among populations at high risk of a second heart attack.
Areas of Ongoing Investigation in Carotenes
||Possible Health Effect
||Secondary prevention of heart attacks
||Prostate cancer prevention
||Cataract, macular degeneration prevention
Pizza for the Prostate? Carrots for the Eyes?
Beta-carotene is just one of hundreds of carotenoids that circulate in the blood, most in trace amounts. Other carotenoids which circulate in fairly plentiful amounts in the human include lycopene, lutein and zeaxanthin. Lycopene is found in tomatoes. Some people have higher concentrations of lycopene in their blood than beta-carotene, perhaps as a result of eating a great deal of food with tomato sauce, such as pizza and pasta. Lycopene levels have been related, in several studies, to a lower risk of prostate cancer. So this is an area of active investigation.
The pigments that carry the carotenoids lutein and zeaxanthin are highly concentrated in the macula of the eye (that part of the eye that we use for day vision). We do not know exactly the reason that it gets concentrated there or the mechanism by which it gets concentrated, but the concentration is higher there than in any other tissue of the body. Thus, there is speculation that these pigments might play some protective role against senile macular degeneration. Once again, this is far from being proven, so don't run to the health food store to buy concentrates of these pigments.
The last point that I would like to make is that there appears to be no harm in taking a daily multi-vitamin and mineral supplement. In fact, there is reasonable evidence that this may convey several health benefits to otherwise healthy people.