Vitamin D, also known as the sunshine vitamin is found in abundance in a sunny country like India. Though Vitamin D deficiency is common in colder regions with bleak exposure to the sun’s rays, a recent report states that there prevails a deficiency in epidemic proportions all over the Indian subcontinent. So much so that it affects almost 70%–100% in the general population.
Though India is one of the world’s largest dairy consumers, since these dairy products are not fortified with Vitamin D (which is essential for calcium absorption), there is a rise in cases of osteoporosis and decrease in general bone health among the population.
Vitamin D sufficiency is required for optimal health besides its role in bone health. There are good reasons that vitamin D sufficiency be maintained during all stages of life, from fetal development to old age. One needs to keep in mind that an adequate calcium intake is also required for maintaining bone health.
Solar ultraviolet-B (UVB) irradiation is the primary source of vitamin D for most people. In general, the health benefits from moderate UV irradiation without excess tanning greatly outweigh the health risks. In the absence of adequate solar UVB irradiation due to season, latitude or lifestyle, Vitamin D can be obtained from fortified food, fish and fish oils, liver, egg yolk and vitamin D supplements.
Insufficient levels of Vitamin D during pregnancy can lead to intrauterine growth retardation, premature labour, hypertension, gestational diabetes, repeated pregnancy losses, low birth weight and increased risk of illnesses in the child such as type 1 diabetes, multiple sclerosis, bipolar disorder and anxiety neurosis. Insufficient vitamin D intake during infancy can result in reduced tooth development, slower growth and rickets because bones develop rapidly during this period. It has also been shown to be related to postpartum depression. Similarly, during puberty, Vitamin D is required for the optimization of bone mineral density (BMD) and production of hormones.
Vitamin D levels in adulthood are important for maintaining BMD. Another benefit of vitamin D is the maintenance of optimal muscle strength and thus athletic performance. A deficiency Vitamin D can cause osteomalacia which is associated with muscle and bone pain.
The Risk Factors
- The primary risk factors for osteoporosis and osteopenia include Vitamin D insufficiency, inadequate calcium intake, lack of exercise, and other dietary/lifestyle factors such as smoking, alcohol abuse etc.
- Certain medications such as corticosteroids (frequently prescribed for the treatment of inflammatory conditions as asthma etc), anticonvulsants, warfarin and methotrexate also contribute to low vitamin D levels and thus low BMD.
- Therefore, adequate vitamin D, calcium consumption and exercise should be maintained to combat both primary and secondary risk factors for low BMD during adulthood.
- It may significantly reduce the risk for at least 17 types of cancers. Tuberculosis risk may be increased among those with low vitamin D levels due to its role in immune function. Apart from these, optimal levels have been implicated in cardiovascular and brain health, diabetes, migraine, rheumatoid arthritis and male fertility.
Vitamin D And Older Adults
The elderly have a particularly strong need to maintain vitamin D sufficiency. They are likely to produce less vitamin D from solar irradiation because they generally spend less time in sunlight than younger people. Their efficiency of photo production is also lesser.
Osteoporotic fractures are of significant concern in this population. It not only adds up to the burden of increasing medical cost but also brings with it disability and dependence. Several factors contribute to the risk of such fractures, including low BMD, muscle weakness and loss of balance/neuromuscular function. Vitamin D sufficiency, adequate dietary calcium/related minerals (eg., phosphorus, manganese, zinc, silicon, boron etc), vitamin K and exercise can help reduce the risk of falls and thus fractures. An added benefit is reduced tooth loss.
Vitamin D Recommendations
The guidelines currently recommend 200 IU/day of vitamin D for children and younger adults, 400 IU/day for those ages 51-70, and 600 IU/day for those over age 70. These guidelines are largely for maintaining bone health.
There is ample evidence that a blood level of 30-50 ng/mL is necessary for optimal health. In the absence of adequate sun exposure, 1,000 IU vitamin D daily for children and adults is required to achieve these levels.
There are concerns that at higher doses (>5,000 IU/day) over extended periods of time, some adverse effects may occur, such as a risk of high blood calcium levels and deposition in soft tissues (calcification). At higher values of 25(OH)D, vitamin D resistance may also occur. The tolerable upper limit is set at 2000 IU/day. It is advisable to consult your Dr. or nutritionist before beginning supplementation.
Guidelines For Soaking Up The Sun
The best time of day for vitamin D production is near solar noon when the ratio of UVB to UVA is highest. The exposure time required for a given level of vitamin D photo production is lowest near solar noon, however, one must stop when the skin just about begins to redden. In addition, skin cancers are probably more susceptible to UVA irradiation than UVB irradiation, so minimizing UVA rather than UVB exposure may be appropriate. Glass windows can block out the UVB rays. Other factors which affect production are latitude, time of day, season, a fraction of the body exposed, use of sunscreens, skin pigmentation and the amount of body fat.