Calcium & Vitamin D ~ An Essential Element for Bone Health

Calcium & Vitamin D ~ An Essential Element for Bone Health
Importance of Calcium There is strong and convincing evidence that calcium is important for building strong bones in childhood, maintaining bone density in adults, and reducing the likelihood of fractures as we age.

Calcium is crucial for life. Every cell in the body needs calcium to function properly. Heart, Nerve and Muscles all need calcium for their activity. Bones need calcium to maintain strength. 99 % of body calcium is in the bones.

Our Body gets calcium from food we eat. If dietary source is deficient in calcium, our body gets it from our bones.

Calcium is essential for bony health for number of reasons. In childhood it is needed for proper formation of bony skeleton to support growing body. By the age 20 bones stop growing in length and by this time peak bony mass is reached. The density of your bones at this point will depend, in part, upon the extent of your calcium intake as a child. The greater this peak bone mass, the less likely your bones are to become porous and fragile later on.

Bone is living tissue, constantly renewing itself. Daily wear and tear causes structural defects which need to be taken care of. This process in the bones is termed as Bone remodelling. Remodelling is an ongoing, natural process and the cycle is completed every three to four months in a healthy young adult. With age this maintenance system becomes less efficient. In people who have relatively healthy bones, adequate calcium intake can help the remodelling process stay balanced. This means that replacement of new bone will remain more efficient, thus preventing a rapid decline in density.
Calcium and Menopause
Calcium is especially important at menopause because calcium absorption seems to slow down with the decrease in estrogen.
How Much Calcium Do You Need?
Following nutritional intake of calcium every day is essential, to maintain strong bones.

Recommended Daily Calcium Intake

birth-6 months – 400 mg / day
6-12 months – 600 mg / day
1-5 years – 800 mg / day
6-11 years – 800-1200 mg / day
Adolescents & Young adults
11-24 years – 1200-1500 mg / day
25-50 years – 1000 mg / day
Pregnant or lactating women – 1200-1500 mg / day
Postmenopausal women on estrogen – 1000 mg / day
Postmenopaural women not on estrogen – 1500 mg / day
Men (25-50 years) – 1000 mg / day
All women and men above 65 – 1500 mg / day
Is There Such a Thing as Too Much Calcium?No adverse effects have been observed in people who consume well above the recommended daily intake of calcium (up to 2500 mg per day). A high dietary intake of calcium used to be suspected of increasing the risk of kidney stones, but most experts now believe that this is incorrect.


Absorption of calcium

Absorption of calcium
The amount of calcium in food items that we eat is absorbed differently. Like the calcium in spinach and calcium in milk is absorbed to the blood differently. The absorbability of calcium from spinach was compared with the absorbability of Ca from milk in healthy adults. Absorption was higher from milk in every case, with the mean absorption from milk averaging 27.6% and from spinach, 5.1%.

Thus, spinach Ca is much less readily available than milk Ca.

The presence of lactose (milk sugar), lactase (the enzyme that breaks down lactose), and the acidic amino acids, lysine and arginine, are all factors that improve calcium absorption.

Decreased absorption is associated with diets high in fiber. Foods such as whole grains and spinach are high in phytates and oxalates, compounds known to bind with calcium and reduce absorption.

Vitamin D intake is a second factor, as active calcium transport is directly and proportionally dependent on the presence in the intestinal cell of calbindin D9k, the biosynthesis of which is totally vitamin D dependent. 

Absorption in jejunum and ileum is the major absorptive process when calcium intake is adequate. No more than 10% of total calcium absorption takes place in the large intestine.