In recent years a growing number of reports have appeared which concluded that some of today's foods are not as nutritious as those eaten in the past. A report in the Journal of Complimentary Medicine in 2001 pointed out that US and UK Government statistics show a decline in trace minerals of up to 76% in fruit and vegetables over the period 1940 to 1991. (1)
In 2003 News Canada reported that today's fruit and vegetables contain far fewer nutrients than they did 50 years ago. They claimed that potatoes, tomatoes, bananas and apples were notably less nutritious. For example, the study (source unidentified) found that potatoes had lost 100 % of their vitamin A content, 57% of their vitamin C and iron, and 28% of their calcium. The report went on to examine data from the US Department of Agriculture involving vegetable quality, which showed that over the entire 20th century the average mineral content of such vegetables as cabbage, lettuce, spinach and tomatoes (a fruit!), declined from 400mg to less than 50mg. (2)
In 2004 a report in the Journal of the American College of Nutrition examined food composition changes from 1950 to 1999 recorded in the USDA food composition tables. Forty-three crops were examined – mostly vegetables. The conclusion was that there were statistically reliable declines for 6 nutrients. The declines were observed in protein, calcium, phosphorous, iron, riboflavin and ascorbic acid. The declines were not insignificant. e.g. 6% in the case of protein and 38% for the B vitamin riboflavin. (3) The UK publication Food Magazine early this year published an analysis of food quality changes in the UK over the period 1940-2002. The analysis was based on the well-known food composition tables published on a regular basis by McCance and Widdowson. (4) In an analysis of milk it was concluded that the iron content had fallen 62%, magnesium – another commonly deficient element, was down 21% and the copper content had disappeared completely. In the context of magnesium it is interesting to note that its levels fell in almost all foods examined – a mere 4% in turkey meat but dramatically lower quantities in many cheeses. Parmesan cheese was the worst affected recording a 70% fall in value. The calcium and iron content of all the foods examined was reduced dramatically in every instance e.g. the iron content of a beef rump steak fell 55%.