DEAR DR. BLONZ: I've always thought that if I have all my fruits, vegetables and grains -- organic, when possible -- along with other foods in the amounts recommended, I should not need any dietary supplements. Recently, I attended an anti-aging conference where I was told that the soil throughout the United States is 85 percent depleted of its vitamins and nutrients. They said eating organic does not mean you are getting your fruits and vegetables from nutrient-dense soil. Is this a fact? I am hoping you can help me identify areas of the country, or the world, where a person can be sure to get produce with the proper nutrients. -- R.V., San Dimas, California
DEAR R.V.: The information from that anti-aging conference was off the mark. While I am definitely pro-organic and support it when possible, it is better to eat conventionally grown produce than to limit your intake of fruits and vegetables.
The often-heard "soil-depletion" argument can be very misleading. In addition to their need for sun, water and proper temperature, fruits, vegetables and grains -- whether grown organically or through conventional methods -- require certain nutrients to develop. If a plant's essential minerals are not in the soil, for example, the plant simply won't grow, or it will fail to develop normally.
Minerals that aren't needed can also be taken up by a plant. Foods grown in selenium-rich soil, for example, often contain more of this mineral than the same plants grown in selenium-poor soil. A plant's mineral content can also vary according to the time of the growing season and the length of time the plant has had to grow.
The idea of "vitamin-depleted" soils makes even less sense. Plants do not get their vitamins from the soil; they, along with other phytochemicals, are synthesized within the plant itself. The amount of a particular vitamin found in a fruit, vegetable or grain is determined by the plant's genes, not by the amount present in the soil. After harvest, vitamin content can decline with time, and some vitamins can be affected by cooking.
It then follows that there really isn't a specific area of the country (or the world) where a person can be sure that the fruits and vegetables have the "proper nutrients and vitamins." If you are concerned about the adequacy of your diet, if you have health issues or are at risk for certain chronic diseases, there are a number of websites where you can enter the foods you eat and get a report of nutrients consumed. As is typical of today's online "diet," some of these sites charge money, while others provide the service for free -- but with a "side dish" of advertisements.
Variety is key wherever you live, and we are blessed with a transportation system that brings us foods from all over. Eating well is the cornerstone of good health, and a good diet places you head and shoulders above the vast majority of your peers.
Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to email@example.com. Due to the volume of mail, personal replies cannot be provided.