In 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 to look for possible changes in the nutrient content of 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 categories, including calories, protein, fat, carbohydrate, calcium, phosphorus, vitamin A, ash (mostly potassium), iron, thiamin, riboflavin, niacin and vitamin C (ascorbic acid).
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.
It is unclear where the USDA came up with their information, however. 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 and pale tomato to a large, red and 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 for the comparison to be accurate would be if the tests in 1950 and 1999 were done in the same laboratory, on the same machines, using the same protocol for testing.
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. Fruits and vegetables are low-calorie, high-nutrient foods that have vitamins, minerals, fiber and crucial phytonutrients (plant nutrients.) Processed foods are clearly not an alternative, and yet they make up a lot of our meals these days. 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 is a huge problem in this country.
Do not worry if the quality of your fruits and vegetables are not what they used to be 30 or 40 years ago. Just make sure to have at least 5 servings of fruits and vegetables in your diet every day. Choose SuperFoods like blueberries, spinach, oranges, pumpkin, broccoli, tomatoes, apples, kiwi, pomegranate, avocado and onions to maximize your intake of phytonutrients.