OSTEOPOROSIS: HOW MUCH CALCIUM DO YOU ABSORB?

When you eat food containing calcium, it passes along the gastrointestinal tract, with calcium absorption occurring throughout the length of the small intestine, diffused through the intestinal wall and transported by your bloodstream. The bloodstream carries calcium to body organs and tissues, for vital organ functions, and to storage in the bone cells as mineralization. Calcium is excreted in the urine and stools, and some in perspiration through the sweat glands. How much is actually absorbed by your body to aid mineralization? Absorption of dietary calcium in the intestines is incomplete, ranging from 10 to about 50 per cent of intake, depending on several factors varying with:

your age, with the differing interplay of hormones,

your general health and lifestyle, such as habits of smoking

and alcohol use,

your intake of other nutrients such as vitamins,

your level of emotional stress,

your level of physical stress and amount of exercise, and

certain medication you may take for chronic conditions

or diseases.

A breast-fed baby receives about 60mg of calcium per kilogram of body weight, and retains 66 per cent of this amount. In contrast, a baby fed formula with standard cow’s milk receives about 170mg of calcium per kilogram of body weight, but retains only 25 to 30 per cent. Because of the greater absorption of calcium from human milk, it better fulfils calcium needs.

From the age of one to ten years, the retention of dietary calcium is not as high as during babyhood, but growing children still need about twice as much calcium per unit of body weight as adults do.

Between eleven and eighteen years of age there is usually much accelerated growth of skeleton and muscles, although the retention of calcium can be variable. During these formative years, good nutrition is especially important, with attention paid to daily calcium intake, if the strongest potential skeletal mass is to be attained.

With bone tissue being constantly remodelled, and adult bone not being static, 600 to 700mg of calcium may enter and leave the bones each day.

During pregnancy, in spite of the increased efficiency in absorption, calcium needs are increased above the non-pregnant state. Nutrients, including calcium, are passed to the foetus through the blood circulation of the mother, so it is crucial that a woman has an immediate concern for her extra daily calcium needs as soon as she knows she is pregnant. In fact, it’s a good idea to build up calcium levels before becoming pregnant. A full-term baby contains about 25 g of calcium: skeletal tissue starts to form during the third month of pregnancy, with most calcium deposited during the last trimester at a rate of200 to 300mg daily. Towards the end of pregnancy, when a mother stores additional calcium in preparation for lactation, it is important to continue adequate intake of the mineral.

During breast-feeding, the amount of calcium secreted in breast milk may amount to 250 to 500 mg each day. If a mother has an extremely heavy flow of milk, considerable losses of calcium may occur, making it vital for her calcium to be replenished to safeguard her bones and those of her child.

if you have children in quick succession, with or without breast-feeding, your skeletal mass may be depleted of calcium, especially if you are still adolescent.

Calcium absorption can be influenced by your general level of health, with decreased absorption during an illness and in later years, starting at the age of forty-five for women and sixty in men. Exercise improves calcium absorption, making workouts work better, while prolonged inactivity (such as a long illness) can decrease absorption.

Some medications such as antacids, tetracyclines, laxatives, diuretics, and heparin obstruct calcium absorption.

If you smoke, drink alcohol or many beverages containing caffeine, consume a high-protein diet, use excessive amounts of salt, or have a sedentary lifestyle, you want more calcium, and need extra servings of calcium-rich foods.

During and after menopause, with the changing balance of hormones controlling calcium utilization, coupled with reduced intestinal absorption, and possibly a less active life, calcium requirement is even greater.

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