Improved diets and lifestyles needed to help prevent certain chronic disorders

Scientists from around the world emphasized the need for foods rich in calcium and vitamin D as the best way to assure adequate intakes and help prevent such disorders as poor bone formation and growth at a major congress held in Rome earlier this month.

The First World Congress on Calcium and Vitamin D in Human Life, organized by FAO, the World Health Organization (WHO) and other institutions working on nutrition, discussed ways to improve these nutrient intakes among all population groups and to promote proper growth during infancy, childhood and adolescence.

Calcium and vitamin D vital for growth

Throughout the life cycle, calcium and vitamin D are essential for proper growth and development and good health.They are particularly important during the periods of rapid growth in childhood and adolescence, and during pregnancy and lactation.

Inadequate dietary calcium is associated with a number of common chronic medical disorders worldwide, such as osteoporosis, cardiovascular disease -- hypertension, stroke and ischemic heart disease -- diabetes and hypertensive disorders of pregnancy, obesity and colon cancer.

Inadequate intake of vitamin D is associated with bone abnormalities, such as rickets, and with a decrease in the body's ability to absorb calcium.Osteoporosis, in particular, a deterioration of the skeleton resulting in fragile bones and increased fractures associated with the ageing process, is a major public health problem and is among the most important causes of long-term disability.

Congress highlights

Overall diet and lifestyle
One of the outcomes of research on the role of calcium in health and development is an increasing recognition of the complex interaction among various nutrients including calcium and phosphorus, magnesium, sodium, zinc and iron. High protein, sodium and alcohol intakes can also affect calcium utilization and metabolism.

While further research is needed to better understand these relationships, it is clear that eating a variety of foods and maintaining a balanced diet and regular physical exercise are fundamental to controlling some of the diseases associated with low levels of calcium intake. Most of the body's requirement for vitamin D, essential throughout life for maintaining calcium and bone metabolism, can be formed in the human body when there is regular exposure to sunlight. Vitamin D is also available from animal products such as fish and fish liver oils, eggs and meat, and vitamin D fortified foods such as milk. For forming and maintaining proper bone health, sufficient levels of calcium, vitamin D and physical exercise must be achieved.

Calcium levels
In determining adequate intake levels, the balance of calcium in the system is the most important factor. Calcium intake cannot be looked at in isolation. Many factors affect the body's absorption or excretion of calcium, such as vitamin D, protein, sodium and alcohol, and these must be taken into consideration. Moreover, responses to different calcium intakes differ widely among individuals and populations; the issue of adaptation needs to be further explored. Because of this, it is not appropriate to establish and promulgate recommended intake levels worldwide. Countries should be encouraged to set recommendations for their own populations.

Dietary calcium intake and physical activity interact with genotype in the determination of bone mass. Adequate calcium and vitamin D levels are essential for the development and maintenance of a normal skeleton. Improper nutrition and diet is an important factor in at least one-third of the cases of osteoporosis. The intake of a number of nutrients (calcium, sodium, protein), trace elements (zinc, copper, magnesium) and physical activity has an important effect on the prevention and treatment of osteoporosis. Vitamin D levels play a particularly important role in the prevention of hip fractures.

Low calcium intake has been shown to produce a rise in blood pressure, with the related consequences on health. Increasing calcium intake can have a beneficial effect on preventing this rise, which is of particular importance during pregnancy, as an increase in blood pressure can seriously jeopardize the health of both mother and child.

Pre-eclampsia, a disorder of high blood pressure and kidney failure that can occur during pregnancy, increases the risk of pre-term births, low birth-weight babies and caesarean sections and is potentially fatal. Mothers' calcium intake during pregnancy may also be related to future blood pressure levels in their offspring.

In pregnancy, calcium requirements increase; the risk of hypertensive disorders during pregnancy can be lowered by controlling calcium intake. The interaction between calcium and sodium is important; as calcium increases sodium excretion, reducing sodium intake may be just as effective as increasing calcium intake.

Colon cancer
In vitro studies indicate that calcium has a role in regulating tumor activity, but evidence is still unclear whether this is also true for humans. Further research is indicated to establish the extent to which calcium also has a role in normalizing cell growth in humans. Clinical trials carried out so far include only studies where the disease is well-advanced and calcium is thought to be no longer effective. Research is particularly needed in the area of prevention rather than treatment.

The congress has been an important step in understanding the complex role of calcium and vitamin D in obtaining and maintaining good health and nutritional well-being. It will be a useful resource for future discussions and research.

Three areas for follow-up have been clearly identified: further research, especially in understanding the interactions of various important nutrients and the resulting health consequences; nutrition education for the public to prevent disorders associated with inadequate levels of calcium and vitamin D; and production and promotion of foods rich in calcium and vitamin D.

FAO and WHO will hold a joint expert consultation in 1997 to further explore the issues discussed at the congress and to formulate recommendations.

The First World Congress on Calcium and Vitamin D in Human Life was organized by FAO, WHO, the Italian National Institute of Nutrition (INN), the Italian National Research Council (CNR) and the Italian National Federation for Osteoporosis Centers (FNCO).

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