How many times has a customer asked you, “Do I really need to take vitamins? Can’t I get what I need by just eating a good diet?” Or perhaps even, “My doctor says I don’t need to take vitamins, just eat a good diet.” How do you respond to this? Are you successful in overcoming these objections? If you’d like to provide such customers with an intelligent, convincing answer, you need to consider two key issues: The adequacy of vitamins and minerals in our food supply and the dietary habits and nutrient intakes of Americans.

An examination of our food supply over a 90-year period does show the nutrient level of foods in general has improved, albeit only modestly. However, it is also true that despite improvements in agricultural techniques that have improved crop yield, from 1909 to 1994 a decrease in the levels of key nutrients has occurred. The vitamin B12 levels in foods decreased about 5 percent, magnesium decreased about 3 percent, zinc decreased about 3 percent, and potassium decreased about 7 percent.¹ Of course on the face of it, a 3 percent to 7 percent decrease of key nutrients doesn’t sound too bad. On the other hand, this is a decrease of nutrients across the whole food supply. An examination of individual crops reveals more severe declines. For example, growing conditions have caused certain crops to experience a 20 percent decrease in vitamin E and the essential unsaturated fatty acid linoleic acid.² Other studies have shown growing conditions can affect the calcium level of some crops by as much as 300 percent.3 Likewise, certain agriculture technologies decreased vitamin C and E levels in some crops by 2 percent and 13 percent, respectively;⁴ the content of seven minerals decreased in those same crops.

Aside from growing conditions and agricultural technologies, there is the simple fact that the nutrient content of foods can be directly related to the nutrient content of the soil in which they were grown. For example, the selenium content of plants, in particular cereal grains, is strongly influenced by the quantity of biologically available selenium in the soil in which they grow, that is, by their geographical origin.⁵ As a result, it should not be too much of a surprise that, according to the U.S. Department of Agriculture (USDA), the selenium content of fruits and vegetables is normally very low.⁶

In addition to the aforementioned issues, research has also shown food preparation may decrease the activity of some vitamins. Keeping food hot for more than two hours, for example, results in more than 10 percent losses of vitamin C, folate and vitamin B6.⁷ Vitamins are also lost during chilling, storage and reheating, including more than 30 percent of vitamin C and folate.⁸