Vitamin D Deficiency

Vitamin D comprises a group of fat-soluble compounds that are essential for maintaining the mineral balance in the body. The vitamin D form synthesized in humans is called ‘cholecalciferol’ (vitamin D3). As cholecalciferol is synthesized in the skin by the action of ultraviolet light (UVB), vitamin D does not fit the classical definition of a vitamin; nevertheless, it is recognized as an essential dietary nutrient.

The sun is our major vitamin D source. However, several factors such as sunscreen with a sun protection factor above 8, age, darker skin pigmentation, northern latitude greater than 40 degrees and the winter season reduce the production of vitamin D in the skin.

A sufficient intake of vitamin D (calciferol) is important as it helps the body to

• maintain healthy blood levels of calcium and phosphorus

• build and maintain healthy bones

• control cell division and specialization

• modulate the immune system

• the maintenance of normal bones and teeth

• the normal function of the immune system and healthy inflammatory response

• the maintenance of normal muscle function

• normal absorption/utilization of calcium and phosphorus and maintenance of normal blood calcium concentrations

• normal cell division

In addition, vitamin D plus calcium are needed for the maintenance of normal bone.

Conditions / Diseases risk

Bone disorders : Adequate amounts of vitamin D throughout one's life - in combination with exercise, proper nutrition, calcium, and magnesium - are necessary for building up and maintaining bones and preventing bone loss. Vitamin D is needed to properly absorb calcium. Studies have shown that low levels of vitamin D and insufficient sunlight exposure (fewer than 20 minutes per day) are associated with osteoporosis. Calcium, together with vitamin D, has been shown to help heal bone fractures from osteoporosis and decrease the risk of future bone breaks. In addition, vitamin D has demonstrated a beneficial effect on muscle function and strength and thereby reduces the risk of falling. Moreover, vitamin D is well known to protect against ‘rickets’ and ‘osteomalacia’, diseases of severe vitamin deficiency.

Cancer : Studies in test tubes have indicated that vitamin D may have anti-cancer effects, while clinical study findings on vitamin D and specific cancers such as colorectal cancer have been inconsistent. However, some studies have shown strong evidence that high doses of vitamin D supplements may reduce the risk of colorectal cancer. In addition, some population studies have suggested that supplementation with vitamin D may improve survival rates in those with a history of breast cancer. Other studies indicated that vitamin D3 supplementation might be effective in treating skin cancer. However, this research is still in the experimental stages.

Autoimmune diseases : Research suggests that vitamin D deficiency or a low vitamin D status may be linked to an increased risk of developing autoimmune diseases, overactive immune responses of the body attacking its own cells and organs. Clinical studies evaluating the use of vitamin D for some forms of arthritis (e.g. rheumatoid arthritis and osteoarthritis) have found vitamin D to have preventive effects. Observational data has suggested that vitamin D from foods and sunlight may help protect against multiple sclerosis (MS), a disease in which the body's immune response attacks a person's brain and spinal cord. Research has shown that supplementing infants and children with high doses of vitamin D may protect against the development of type 1 diabetes, a disease in which the body’s immune system destroys the insulin-producing cells.

Cardiovascular disease and High blood pressure Data from clinical studies have suggested a link between low levels of vitamin D and high blood pressure. Moreover, low vitamin D status (as measured by the 25(OH)-vitamin D plasma level) is thought to be independently associated with all-cause and cardiovascular mortality or a higher risk of a heart attack.

Other disorders : Although the information is limited, studies have suggested that vitamin D supplementation may also be helpful to prevent Seasonal Affective Disorder (SAD), a form of depression that occurs during the winter months because of lack of sunlight, and tuberculosis, an infectious disease.

Deficiency

Reports from across the world indicate that vitamin D insufficiency is widespread and is re-emerging as a major health problem globally.

In vitamin D deficiency, calcium absorption cannot be increased enough to satisfy the body’s calcium needs. Consequently, calcium is mobilized from the skeleton to maintain normal serum calcium levels, resulting in bone loss.

One of the most frequent childhood diseases in many developing countries is ‘rickets’, a softening of bones, caused by severe vitamin D deficiency and thus potentially leading to bowed legs and arms and other deformities.

Osteoporosis (‘brittle bones’) is a disease in which the quality and density of the bone is reduced, thus increasing the risk of fractures. It usually occurs in people of older age, but can happen to anyone at any age. Osteoporosis is a silent disease. Often there are no symptoms until the first fracture occurs. Osteoporosis has been associated with less obvious states of vitamin D deficiency, called vitamin D ‘insufficiency’.

Groups at risk

• infants who are exclusively breast fed (human milk is a poor source of vitamin D)

• premature and low-birth-weight infants

• elderly people (reduced capacity to synthesize vitamin D in the skin by exposure to sunlight)

• people with diseases affecting the liver, kidneys or have impaired fat absorption

• vegetarians

• alcoholics

• overweight or obese people (reduced ability to produce vitamin D in the skin and to absorb it through the intestines)

• people who are housebound (lack of sunshine exposure)

• dark-skinned people produce less vitamin D from sunlight

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