There are three basic reasons we can't get enough magnesium in the diet:

1. Reduced levels due to processing.
2. Reduced levels due to soil conditions.
3. Changes in eating habits.

Food processing essentially separates plant food sources into components, both for ease of use and to reduce spoilage. In processing grain into white flour, the bran and the germ are removed. In processing seeds and nuts into refined oils, the oils are super-heated and the magnesium content is strained out or removed through the use of chemical additives. It is these removed portions of the plant that often contain the highest amount of minerals such as magnesium.

• Refined oils remove all magnesium. The result of oil refining is a zero magnesium product. Safflower seeds, for example, contain 680 mg of magnesium per 1,000 calories. Safflower oil lacks magnesium entirely.
• Refined grains remove 80-97 percent of magnesium. At least twenty nutrients are removed in refining flour. And only five are put back in when refined flours are "enriched". Magnesium is not one of them.
• Refined sugar removes all magnesium. Molasses, which is removed from the sugar cane in refinement, contains up to 25% of the RDA for magnesium in one tablespoon. Sugar has none.

It is well known among experts that the quality of our crops is decreasing. In 2004, the Journal of the American College of Nutrition released a study which compared nutrient content of crops at that time with 1950 levels. Declines were found as high as 40%.

Dr. Donald Davis, lead researcher for the study, offers one explanation for the dramatic declines:

During those 50 years, there have been intensive efforts to breed new varieties that have greater yield, or resistance to pests, or adaptability to different climates. But the dominant effort is for higher yields. Emerging evidence suggests that when you select for yield, crops grow bigger and faster, but they don't necessarily have the ability to make or uptake nutrients at the same, faster rate."   

Declines are not limited to vegetable crops. A study by David Thomas published in Nutrition and Health examined average nutritional content of foods across food categories using the UK government's Composition of Food tables.

Thomas found consistent declines in magnesium content:

• Vegetables declined by 24% between 1940 and 1991.
• Fruit declined by 17%.
• Meat declined by 15%.
• Cheeses declined by 26%.

Our crops' lack of magnesium and other nutrients has a direct impact on the ability to achieve sufficient magnesium in the diet. Ultimately, even those who seek out a balanced high magnesium diet with magnesium-rich vegetables and whole grains may not be able to rely upon food alone to provide sufficient magnesium levels. 

Next month I will look at how pesticides and modern farming practices decrease available nutrients like magnesium in our food.