DEAR DR. BLONZ: I support the importance of having whole foods in our diets. But I am troubled by constantly reading that the soil is depleted of minerals -- the same minerals we assume will be present in our foods. If that’s the case, the produce we eat might not be providing our bodies with the nutrients we need. However, it is my understanding that produce requires certain nutrients to grow to proper size, shape, color, taste, etc. Therefore, it seems illogical to me that the produce of today would not have the same nutrients as it would have had in previous eras with “non-depleted” soil. Please advise. -- S.T., Arlington Heights, Illinois
DEAR S.T.: You can think of plants as miners, pulling the mineral elements required for their growth out of the soil. Add water, energy from the sun, and the appropriate climate, and the game is on.
You are correct in your assumption that if a mineral needed by the plant is unavailable, the plant will fail to thrive; it is doubtful such produce would ever find its way to the market. That indeed makes it incorrect to think that today’s fruits, vegetables or grains would provide any less of the essential nutrients than the same varieties of these plants had provided in the past.
Mineral elements are key here, because unlike humans, plants synthesize their own vitamins. So vitamins will definitely be there, as required by the plant, and will be available for us after the food is consumed, digested and absorbed.
There is another layer to this question, however, as nonessential minerals in the soil can also end up in a plant. Whole foods grown in iodine- or selenium-rich soils, for example, can have more of these nutrients than the same type of food grown in soils with lesser amounts of these minerals.
What gets pulled in can differ from plant to plant and mineral to mineral -- even among different varieties of the same fruit, vegetable or grain. The plant’s overall nutrient content can also vary according to the time of the growing season and the length of time the plant has had to grow. This means that a plant picked green may not have the same nutrient content as one allowed to ripen on the vine.
It is difficult to speak with any statistical certainty, because we don’t have records of nutrient content from the produce of a hundred years ago. Based on what we know, however, it’s likely that the amounts would be comparable.
Send questions to: “On Nutrition,” Ed Blonz, c/o Andrews McMeel Syndication, 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.