Think about this scenario: A large study links eating tomatoes, red carrots and red bell peppers to healthier eyes. Lycopene is the common active nutrient in the vegetables with a known role in eye health. Trials are run with participants taking lycopene supplements but the effects on eye health are much less than was seen in the large dietary study.
How many times has this scenario been repeated? Eating almonds has a greater effect than taking vitamin E supplements, eating sweet potatoes and carrots is more effective than taking vitamin A supplements and eating dried beans or spinach has more health impact than taking potassium supplements.
These follow-up findings never receive as much media coverage as the initial linking of a particular nutrient to a health problem. The supplement makers(chemical companies) want you to believe taking a pill is as good as eating whole fruits and vegetables. The supplement makers pay for most of the studies. And if lycopene is good for eye health, then everyone should take a lycopene supplement every day, right? The fact that eating a little bit of tomato or red bell pepper every day would be even better for our eyes does not need to be advertised.
Why does this scenario keep reappearing in study after study of dietary supplements?
Nutrition is synergistic. Vitamins, antioxidants, minerals and other essential nutrients do not act alone. The chemical interplay that allows a nutrient to go from a vegetable to where it is needed in a human body is too complex for any current doctor or scientist to understand. A nutrient might need the presence of another nutrient, fat or mineral to be absorbed through the intestinal wall. Some nutrients need the host vegetable to be cooked to become available. A trace mineral might need a particular enzyme in its host fruit to enter the cells where it is most effective.
Supplements often do some good but most of the dose is excreted from the body unused. Supplements are very wasteful. A lot of energy is used to isolate individual nutrients from whole plants or to manufacture them from raw chemicals.
Whole foods are much more energy-efficient to grow and get to market. Whole foods are also much more effective at providing needed nutrients.