Ask the Doctor: Nutrients in Food : SuperFoodsRx

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Ask the Doctor: Nutrients in Food

Question: Dear Dr. Harris, A friend told me that a recent study showed that the fruits and vegetables we eat today are actually less nutritious than they were 50 years ago. Is this true? What should I do?
Answer: Your friend is probably referring to an article published in the Journal of the American College of Nutrition in 2004. Dr. Donald David led a group of researchers at the University of Texas who looked for possible changes in nutrient content in 43 fruits and vegetables from 1950 to 1999. Using the USDA-published nutrient content data from 1950 and 1999, they compared the nutrient content ¬¬for each fruit and vegetable by focusing on 13 nutritional categories, including calories, protein, fat, carbohydrate, calcium, phosphorus, vitamin A, ash (mostly potassium), iron, thiamin, riboflavin, niacin, and vitamin C (ascorbic acid).

In order to compare the USDA data and try to standardize the information, they adjusted the published nutrient contents to account for moisture content in the produce. The researchers found a statistically significant nutrient decrease in the fruits and vegetables from 1950 to 1999 for 6 nutrients: protein (-6%), calcium (-16%), phosphorus (-9%), iron (-15%), riboflavin (-38%), and ascorbic acid (vitamin C) (-15%). There was no significant difference for vitamin A, thiamin, niacin, fat, or carbohydrate content from 1950 to 1999.

But, is this something to worry about? I don't think so. The study was prepared using data from the USDA, and it is unclear where the USDA came up with their information. It seems that some of the 1950 data came from other published literature and may not have been representative of the food supply at the time. Also, comparing produce is difficult. Tomatoes are not like Twinkies manufactured in a factory with standardized production output. Fruits and vegetables of the same type may have different nutrient content due to size or ripeness. An extreme example would be to compare a small, pale tomato to a large, red, ripe tomato. The comparison becomes even more complex when you consider regional differences in soil, seasonal changes in produce, climate changes for each year (rain, temperature, and sunlight), and source of the food (home garden, farmer's market, or grocery). The only way to be completely accurate in the comparison would involve testing the produce from 1950 and 1999 in the same laboratory, on the same machines, using the same protocol for testing. This is not feasible.

More worrisome is research that comes from the studies showing that Americans still aren't getting their "five-a-day." Fruits and vegetables are low-calorie, high-nutrient foods that have vitamins, minerals, fiber and crucial phytonutrients (plant nutrients.) Processed foods clearly are not an alternative to fruits and vegetables. Even with possible small decreases in the nutrient value of produce, whole foods are still nutrient powerhouses and an important part of our diet. Over consumption of fast food and processed food are a growing problem in this country. A more dramatic study would be to compare the nutrient content of a 1950's diet to a modern diet. Despite better access to fresh fruit and vegetables all year round, we are not getting our recommended amounts of fruits and vegetables.

Try to be sure to include at least 5 servings of fruits and vegetables in your daily diet. Choose SuperFoods like blueberries, spinach, oranges, pumpkin, broccoli, tomatoes, apples, kiwi, pomegranate, avocado, and onions to maximize your intake of phytonutrients.

Hope this helps,

Geoffrey Harris, MD

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