Is Our Food Becoming Less Nutritious?
A comparison of the nutrient content of 43 different garden crops between the years 1950 and 1999 showed significant decreases in six nutrients, reports a study in the Journal of the American College of Nutrition (2004;23:669–82).
Shifting agricultural practices over the past 50 years have raised the question of how food quality may have been impacted by these changes. A previous comparison of food nutrient quantity in England found an apparent decrease in seven minerals found in fruits and vegetables.
The new study compared foods such as broccoli, tomatoes, Brussels sprouts, strawberries, and green peppers. Different nutrients were compared, including calcium, iron, riboflavin, vitamin C, niacin, vitamin A, phosphorus, and thiamin. Amounts of protein, carbohydrates, fat, and calories were also compared.
When all of the foods were compared as a group, significant declines were seen between 1950 and 1999 in the amounts of calcium, phosphorus, iron, riboflavin, vitamin C, and protein. Riboflavin content showed a dramatic 38% decrease, and calcium was significantly decreased by 16%. Vitamin A, thiamin, niacin, fat, and carbohydrate contents did not appear to change significantly over the 50-year period.
The authors suggested that a possible explanation for the apparent declines in food nutrient content might be related to genetic variations among cultivated crops (cultivars). When certain cultivars are selected for their disease resistance or for higher crop yields, there may be a corresponding decrease in the nutrient content of the plant. This trade-off between different plant characteristics is commonly seen in agricultural practice. An example of a known nutrient trade-off involves wheat crops. One study compared 14 different varieties of wheat and found that the varieties with higher yields also had consistently lower iron and zinc levels. It is possible that cultivars selected for higher yields may not be able to adequately extract soil nutrients and synthesize their own nutrients effectively.
The authors of the new study suggest that different farming practices such as organic growing methods are not likely to affect the amounts of nutrients in plants. However, other studies indicate that organically grown foods may contain higher levels of certain nutrients such as antioxidants and minerals than conventionally grown produce.
Finally, the authors suggest that eating whole foods—those that are not refined and stripped of their nutritional value—would be the best way to offset any potential nutrient deficits that may occur as a result of newer farming practices. It would also be advisable to eat organically grown foods that have not been genetically engineered. Genetically modified plants have been altered to contain genes from other plants and animals; these techniques differ from selective breeding and cross-pollination methods and are not natural.
Because of nutrient loss in food, people should consider taking a multivitamin-mineral supplement to compensate, even if their diet consists primarily of unprocessed, whole foods.
Kimberly Beauchamp, ND, received her bachelor’s degree from the University of Rhode Island and her Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. She is a co-founder and practicing physician at South County Naturopaths, Inc., in Wakefield, RI. Dr. Beauchamp teaches holistic medicine classes and provides consultations focusing on detoxification and whole-foods nutrition.
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