Micronutrients in the Diets of Industrialized Countries

In the USA and Western Europe, agriculture and the food industry produce enough to feed the population and export large quantities of food. Despite this, many people are poorly nourished: they are oversupplied with foods rich in fat, protein, sugar, and salt, and under-supplied with complex carbohydrates, fiber, vitamins, and minerals. Dietary surveys have repeatedly found that micronutrient deficiencies are widespread in the industrialized countries. For example:

• In many large cities in Europe, a quarter of older adults are deficient in vitamin B6, a nutrient vital to the health of the immune sys-tem.1

• The average selenium intake in adults in the UK, in Germany, and in Sweden is only 25-35% of the recommended level.2

• In the USA almost 50% of young women have low iron stores, and more than two-thirds of women develop iron deficiency during pregnancy.3

• In the USA, vitamin D deficiency is found in about 25% of infants4 and 30-60% of older adults.5,6

• The intake of folic acid in 75-95% of young women in Europe is below the level currently recommended to prevent birth defects.7

Why are vitamin and mineral deficiencies so widespread? Five major factors contribute to the problem:

1.Food refining, processing, and storage causes loss of micronutrients.8,9 Modern food processing depletes foods of their natural vitamin, mineral, and fiber content and often adds sodium, fat, and food additives. White flour has only about 15% of the vitamin E, 25% of the vitamin B6, and less than 1% of the chromium found in wholewheat flour.8 9 Potato chips have almost

Common dietary deficiencies of micronutrients in the USA and Western Europe*

USA

Western Europe

Vitamin B6

Vitamin B6

Folic acid

Folic acid

Vitamin A

Vitamin A

Vitamin C

Vitamin C

Vitamin D

Vitamin D

Thiamin

Riboflavin

Calcium

Magnesium

Calcium

Zinc

Iodine

Iron

Iron

* Mean intakes among broad segments of the population are less than 70% ofthe RDAs (1989) and/orthe European Community PRIs (1992). (Sources: Life Sciences Research Office, DHHS. 1989; 89:1255; Hurrell RF. Bibl Nutr Dieta. 1989;43:125; Block G, et al. Ann NY Acad Sci. 1993;678:245; de Groot, et al, eds. Eur J Clin Nutr. 1996;50:S1-127; USDA NFS rep. no. 91-2,1995.)

* Mean intakes among broad segments of the population are less than 70% ofthe RDAs (1989) and/orthe European Community PRIs (1992). (Sources: Life Sciences Research Office, DHHS. 1989; 89:1255; Hurrell RF. Bibl Nutr Dieta. 1989;43:125; Block G, et al. Ann NY Acad Sci. 1993;678:245; de Groot, et al, eds. Eur J Clin Nutr. 1996;50:S1-127; USDA NFS rep. no. 91-2,1995.)

none of the fiber and vitamin C found in potatoes but are high in sodium and fat. Many frozen vegetables lose nearly half of their vitamin B6 content. Oranges and other fruit, picked green and poorly stored, can lose most or all of their vitamin C content.8

2. Modern, intensive agricultural methods deplete the soil of minerals and trace elements. Intensive agriculture, combined with industrial pollution and acid rain, reduces the mineral content of soils. The mineral and trace-element content of many foods varies considerably depending on the soils in which they are grown. Although healthy plants will grow in soils depleted in selenium and zinc, their mineral content will be sharply reduced.

3. People often make the wrong choices in their diets. Typical diets in the industrialized countries emphasize meat, refined grains, whole-milk products, and processed

Micronutrients in the Diets of Industrialized Countries

Loss of micronutrients in food processing and preparation

Food

Method

Micronutrients

Loss (%)

Chicken

Deep frozen

Thiamin, riboflavin, niacin

20-40

Fish

Canned

B vitamins

70

Milk

Pasteurization

Thiamin, vitamin B6, folate

5-10

Milk

Sterilization

Vitamin B6, folate, vitamin B12

35-90

Beef

Roasted

Thiamin, vitamin B6, pantothenic acid

35-60

Pulses (beans, lentils)

Boiling

Copper, iron, zinc, B vitamins

15-50

Strawberries, apricots

Deep frozen

Vitamin C

20-45

Vegetables

Boiling

Thiamin, riboflavin, folate, vitamin C,

30-75

carotenoids

Vegetables

Steaming

Thiamin, folate, vitamin C

30-40

Vegetables (spinach,

Boiling

Magnesium, zinc, calcium

25-40

cabbage, leeks)

Vegetables

Boiling and canning

Vitamin A

20-30

White rice

Boiling

Thiamin, riboflavin, vitamin B6

50

Whole-wheat pasta

Boiling

Iron, magnesium

25-40

Plant oils (safflower oil,

Heat extraction and

Vitamin E

50-70

soybean oil)

refining

Sources: Karmas E, Harris RS, eds. Nutritional Evaluation of Food Processing. 3rd ed. New York: AVI; 1988. Biesal-ski HK, et al, eds. The Vitamins. Stuttgart: Georg Thieme Verlag; 1997.

Sources: Karmas E, Harris RS, eds. Nutritional Evaluation of Food Processing. 3rd ed. New York: AVI; 1988. Biesal-ski HK, et al, eds. The Vitamins. Stuttgart: Georg Thieme Verlag; 1997.

foods. As a result, intakes of sodium, fat, and cholesterol are many times higher than recommended levels, while intakes of fiber, essential fatty acids, and micronutrients are often low.10

4. Polluted urban and industrial environments increase micronutrient requirements. In the major cities of Europe and the USA, millions of people are regularly exposed to air pollution (N02 and O3) above safe levels.11 Pollution in the air, water, and food supply can sharply increase the body's need for antioxidants. High intake of vitamins E and C helps protect against lung damage caused by air pollution.12 Selenium-dependent and zinc-dependent enzyme systems reduce toxicity from heavy metals and other xenobiotics,13 while vit amin C is needed to protect the digestive tract from carcinogens in foods.14

5. Alcohol, tobacco, caffeine, and medicinal drugs all interfere with absorption and/or utilization of micronutrients. More than 90% of older adults take medication daily, and many of the most commonly prescribed drugs impair nutritional health.1516 Thiazide diuretics deplete stores of potassium and magnesium in the body. The contraceptive pill impairs metabolism of folate and vitamin B6 and increases the requirement for these vitamins.17 Smoking sharply depletes stores of vitamin C and vitamin B12 in the body, and alcohol consumption causes widespread loss of iron, zinc, magnesium, and many of the B vitamins.18

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