What is vitamin D?
Interestingly, vitamin D is not actually a vitamin, but a pro-hormone. Most people are familiar with the importance of vitamin D in terms of bone health. Vitamin D is essential for healthy bones and preventing osteoporosis. What many people do not know is that vitamin D is important for so many other components of development, growth, and the maintenance of a healthy body. Vitamin D’s metabolic product calcitriol (1-25-dihydroxyvitamin D) is a steroid hormone. It has an essential role in unlocking the human genome. There are over 2700 binding sites for calcitriol in the human genome. These binding sites occupy sites besides genes associated with nearly every major disease humans suffer from.
There are 2 main forms of vitamin D
Vitamin D2 – ergocalciferol
This form needs to be activated by ultra-violet B light. It is a less effective form to take, as it needs sunlight to be activated.
Vitamin D3 – Cholecalciferol
The active form of vitamin D ready to be converted by the liver to calcitriol. It is derived from Lanolin or cod liver oil and is the preferred form of supplementation of vitamin D.
Health Benefits of Vitamin D
There are multiple health benefits of vitamin D… In fact it is thought to be the single most effective health intervention that can be made to prevent disease. As I stated previously, the most well known role of Vitamin D is regulating calcium and phosphate absorption and metabolism to maintain adequate bone health. This is most especially important during pregnancy and breast-feeding as the baby’s bones are growing rapidly. It is also very important in women after menopause and older people as as we age, we lose bone mineral density.
Additionally, adequate vitamin D during pregnancy is essential as insufficient vitamin D is associated with low-birth weight and prematurity of babies.
Type I Diabetes
A study in Finland published in 2002 showed that babies who were given vitamin D supplementation during the first year of life has a much lower risk of developing type I diabetes. In 2009 a Qatar study and 2010 a Swiss study similarly found that significantly more children with type I diabetes were vitamin D deficient than non-diabetic children.
Vitamin D supplementation over the same period of mother and baby is also associated with a lower risk of developing multiple sclerosis. Additionally the prevalence of MS increases as latitude increases, so the further one lives from the equator, the higher the rates of MS. Although not exactly clear why, it is protective, it is known that vitamin D is important for immune protection and a major theory in the development of MS is caused by viral infection. So it is thought that vitamin D protects against these viral infections. Vitamin D is also effective in treating MS, and there is seasonal variation in symptoms, with much worse symptoms during winter.
Vitamin D and Cancer Prevention
There is a growing body of evidence that suggests vitamin D has an important role to play in the prevention of cancers. It was first noted in the 1980s when cancer maps in the USA were produced. They showed lower rates of colon cancer in the south-west states. Further research showed that the risk of developing colon cancer was inversely associated with blood vitamin D levels. Soon afterwards it was shown that breast, ovary and prostate cancer all had similar inverse associated with sun exposure. The mechanisms for cancer prevention of vitamin D were subsequently discovered.
Vitamin D increases calcium absorption, promotes cell differentiation (the specialization of cells) and cell death (rather than cell proliferation and immortality – which is cancer) and reduces the spread of cancer and the development of a blood supply to the cancer. Calcium works synergistically with vitamin D to decrease cell proliferation and induce cell differentiation.
Current data suggests that adequate vitamin D levels would reduce the risk of 17 cancers including: colon and endometrial cancer by 50 percent, breast cancer and renal cancer by 55 percent, and ovarian cancer by 20 percent.
Vitamin D in the Elderly
Adequate levels of vitamin D in combination with exercise helps prevent osteoporosis in older adults. Those with vitamin D deficiency have a greater risk of hip fractures from falls and studies have shown that vitamin D supplementation can reduce that risk of fractures.
Vitamin D deficiency has also been implicated in infertility, polycystic ovary syndrome, asthma, autism, influenza, and other auto-immune disorders.
Getting enough vitamin D?
There are many people who would not be getting optimal amounts of vitamin D for disease prevention.
It is estimated that 50 percent of people are deficient according to current minimum levels, and in order to prevent these diseases, the vitamin D Council recommends the optimal range of blood vitamin D level be revised upwards. People particularly at risk include:
- darker skinned people
- older people/housebound people
- adolescents and growing children
- breast-fed infants
- Sun avoidance measures (sunscreen/clothing etc)
What is an adequate amount of vitamin D?
The Vitamin D Council recommended daily amounts of vitamin D:
Children less than 1 year = 1,000 IU of D3
Children older than 1 year = 1,000 IU per 10kg up to 5,000 IU of D3
Teens and adults = 5,000 IU of D3
Pregnant and breast-feeding = 6,000 IU of D3
Medications to watch out for
A number of medications interfere with vitamin D absorption. These include:
- anti-convulsants/epileptic medications
People taking these medications should consider additional supplementation with vitamin D.
When to be cautious with Vitamin D supplementation
People suffering from the following conditions should consult their doctor before using vitamin D supplementation due to the risk of developing hypercalcaemia (too much calcium).