There is a big gap between todays nuritional values of products and the ones in the past
The short answer is that, if we get our products from the typical supermarkets, there is no way we can eat enough nutrients we need.
There was a conference several years ago where that same question was addressed from the stage. The host opened a curtain and brought out a big wheelbarrow full of various fruits and vegetables. The answer was “about this much”.
Although the host on stage was indulging in a bit of showmanship, there are enough unbiased studies that support the hypothesis that our foods aren’t as nutritious as they used to be.
Let’s consider how much of some specific items we would have to eat today to get the same nutritional value compared to 40 or 50 years ago. Comparisons over times only have meaning if we look at the nutritional content of a specific nutrient such as vitamin A, C, E or a trace mineral.
A commonly cited study is that of Paul Bergner who used data from various sources, including the USDA, and tabulated the loss of vitamins and minerals in several fruits and vegetables over several decades.
One of his often referenced findings covers the 30 year period from 1963 to 1992 wherein he documented the mineral losses of a dozen fruits and vegetables: He found an almost 30% loss in calcium; a 32% loss in Iron; a 21% loss in Magnesium; an 11% loss in Phosphorus and a 6.5% loss in Potassium.
The implications are that we must eat many more servings of a particular vegetable today to get the same value as we would have gotten 30 years ago.
So we can be conscientious and eat according to the latest USDA Food Pyramid but if the nutritional content of the food is degraded, we are being set up for illness.
One of the vegetables that were included in Bergner’s study is Broccoli. Broccoli is rich in calcium but if there is truly a 30% reduction in the calcium content of broccoli, we would have to eat a little over three servings to get the same calcium benefit as one serving in 1963.
One incredible finding from a different study concludes that it would take 53 peaches to get the same vitamin A content as from one peach several decades ago.
An apparent conflict is found in data from the USDA’s Economic Research Service (ERS). Their data attempts to report the nutritional content of food available for consumption by the entire U.S. population. It examines 10 vitamins, 9 minerals, protein, fat, carbs, cholesterol and fiber; focusing on meat, diary, fruit, vegetables, and grain among others. It generally shows increasing levels of nutrients over the last few decades; not decreasing levels.
The problem I see is that it does not look at individual items of products such as broccoli or peaches and it does include nutrients added through commercial fortification and enrichment.