Low vitamin D means fatter, weaker muscles

Insufficient blood levels of vitamin D may be associated with the accumulation of fat in muscle tissue, leading to lower muscle strength, says a new study.

A study with 90 young women aged between 16 and 22 found that almost 60 per cent were vitamin D insufficient, and that muscle fat levels were higher in these women, compared with women with normal vitamin D levels, according to findings published in the Journal of Clinical Endocrinology and Metabolism.

The findings are said to be the first to show a clear link between Vitamin D levels and the accumulation of fat in muscle tissue, and add to an ever growing body of science supporting the benefits of maintaining healthy vitamin D levels.

In adults, it is said vitamin D deficiency may precipitate or exacerbate osteopenia, osteoporosis, muscle weakness, fractures, common cancers, autoimmune diseases, infectious diseases and cardiovascular diseases. There is also some evidence that the vitamin may reduce the incidence of several types of cancer and type-1 diabetes.

Vitamin D refers to two biologically inactive precursors - D3, also known as cholecalciferol, and D2, also known as ergocalciferol. The former, produced in the skin on exposure to UVB radiation (290 to 320 nm), is said to be more bioactive.

While our bodies do manufacture vitamin D on exposure to sunshine, the levels in some northern countries are so weak during the winter months that our body makes no vitamin D at all, meaning that dietary supplements and fortified foods are seen by many as the best way to boost intakes of vitamin D.

The Endocrine Society issued the guidelines in response to the possible health risks associated with vitamin D deficiency. Among the group's recommendations:

• People who are considered at high risk should be routinely screened for vitamin D deficiency.
• People who are diagnosed with a vitamin D deficiency should be treated with either a vitamin D2 or vitamin D3 supplement.

To maximize bone health and muscle function, people considered at high risk for a deficiency should adhere to the following guidelines for dietary intake of vitamin D:
Infants up to 12 months of age require at least 400 international units (IU) a day.

• Children older than 1 year and adults from 19 to 70 years old, including pregnant and lactating women, should consume at least 600 IU daily.
• People older than 70 years should get a minimum of 800 IU a day.

The task force stressed that in order to raise the blood level of vitamin D consistently above 30 nanograms per milliliter, a significantly higher intake of vitamin D may be required. The group also noted that vitamin D screening is not necessary for people who are not considered at risk for the deficiency. And, it said there is no evidence supporting use of vitamin D supplements for benefits other than bone health.