Osteoporosis is a common disease in the elderly where the bones are not able to retain its mineral density. Over time the strength of the bones are compromised leading to brittle bones. Not only can the bones fracture easily, but may also heal slowly and incompletely. The progression of osteoporosis can be slowed and limited by diet. The importance of calcium and magnesium supplementation is well known in maintaining strong bones but vitamin D is often forgotten for being a key factor in bone health. Vitamin D is somewhat of a unique nutrient in that not only is it sourced from food and supplements, but it can be manufactured when sunlight strikes human skin.
Vitamin D has several health benefits, some of which have been clinically verified. Of these, its impact on bone health is probably best understood and is also the most significant benefit. Calcium along with phosphorus are deposited as hydroxyapatite crystals which are responsible for bone calcification. It is the incorporation of these crystals that makes bone so hard and strong.
However, for calcification to occur there has to be a sufficient quantity of calcium and phosphorus in the blood and tissue fluids and it has to be properly utilized for bone health. Vitamin D plays a central role in regulating the use of calcium and phosphorus in bone composition. It increases the absorption of calcium and phosphorus from the gut and slows down the loss of these minerals in the urine.
Vitamin D is found in many foods and a healthy diet will ensure an adequate intake. However, knowing the foods that are high in vitamin D and incorporating it into one’s diet on a regular basis, even if not daily, can greatly help with bone health. Foods that are rich in vitamin D include offals like liver, oily fish and eggs. It can also be found in smaller yet significant quantities in fortified foods like milk and dairy products, cereals and certain fruit juices.
The amount of vitamin D that one needs depends on age. The recommended dietary allowance of vitamin D for male or female seniors is 800IU or 20mcg per day. If a higher dosage is necessary then supplements may also be included but the total intake from food and supplements should not exceed 2,000IU (550mcg) due to toxicity. The human body, however,can tolerate a maximum of 4,000IU (100mcg). Since vitamin D is also sourced from sunlight, daily intake from foods can be as low as 400IU (10mcg) and still be adequate for bone health.
There are several different forms of vitamin D but the most important is vitamin D3 which is also known as cholecalciferol. This is formed when a substance normally found on human skin, 7-dehydrocholesterol, is exposed to sunlight. Cholecalciferol is then processed in the liver and kidney by a process known as hydroxylation to yield the most active form of vitamin D, calcitriol. This process of deriving vitamin D is so significant that a person who lives in areas with very little or sunlight or remains covered from head-to-toe for long periods will eventually suffer with vitamin D deficiency. Excessive sunlight exposure is not necessary but regular walks in sunlight or sitting outdoors for even short periods is sufficient.
Vitamin D supplements should be prescribed by a doctor or advised by a pharmacist. Patients on osteoporosis medication require vitamin D supplementation. In fact, without vitamin D supplementation while using osteoporosis medication, calcium may be sequestrated from the bones thereby undoing the very effect it was meant to counteract. Vitamin D supplements should be taken in moderate doses of 400IU (10mcg) per day as the remainder of the required vitamin D is sourced from food and sunlight exposure.