Article Tags: Nutrition | seasonal health | prevention | health education | integrative medicine
Vitamin D Essentials:
We need Vitamin D to build and maintain healthy bones. Unless sufficient vitamin D is present our body cannot readily absorb calcium, which is the main component of bone (along with phosphorus, magnesium and other minerals). Vitamin D also regulates many other cellular functions. Its anti-inflammatory, antioxidant and neuroprotective properties support immune health, muscle function and brain cell activity. There also appear to be beneficial effects of vitamin D supplements in autoimmune disease.
Sunshine and vitamin D synthesis
When skin is exposed to ultraviolet B (UVB) radiation from the sun, it converts cholesterol into vitamin D3.
Factors that influence this process and why many people are low in D:
- exposure time of day, season and geographical location (latitude, altitude)
- Amount of body exposed
- air pollution
- skin pigmentation
- sunscreen use
- aging
- sun passing through glass
- There’s still some mystery as to why so many people test low in Vitamin D3 (25-hydroxy vitamin D). Even when exposed to sufficient sunlight or in summertime, many of my patients, including me, test low on blood work.
How much sun exposure is needed
Most people can produce enough vitamin D from sunlight from late March or early April to the end of September. To get enough vitamin D, you can try exposing your face, arms, hands, and legs to the sun for 15–30 minutes, either daily or at least twice a week. People with darker skin may need more time in the sun, and it appears that the darker the skin, the less vitamin D is made.
During the winter when living above and below approximately 33° latitude (San Diego, Fort Worth, Charleston) very little if any vitamin D3 can be produced in the skin from sun exposure. People who live farther north or south cannot make any vitamin D in their skin for half the year. Living in Boston, litterly no vitamin D can be produced from November thru February.
Risks of too much sun exposure
Of course, too much exposure to the sun’s UV radiation can cause skin and eye damage, sunburn, and skin cancer. To protect your skin, you can use sunscreen with a sun protection factor (SPF) of 15 or higher. Make sure you are using the most natural sunscreens as the chemicals are concern for aging.
Other sources of vitamin D
Vit D requirements can be satisfied by eating Vitamin D-containing foods like oily fish, liver, egg yolks, mushrooms, salmon, sardines and fortified foods (although the fortified vitamin D is usually irradiated vitamin D2, and we want more natural D3.
You can also take vitamin D supplements, which are recommended for people with certain medical conditions, darker skin tones, or fat absorption issues. Most people are taking 3,000 to 5,000 IUs daily to support their body levels although the basic recommendations are suggested at lower amounts.
How much is enough?
Adults 18-70 – 600 IUs (15 mcg) (newer ideas suggest 2,000 IUs
Older than 70 – 800 IU (20mcg) (2000-4000 IUs are quite safe)
Considered safe from 1000-2000 IU. Upper limit 4000 IU.
Maintaining blood concentrations of 25-hydroxy-vitamin D above 50-60 nmol/L (approximately 30 ng/mL) is essential.
Vitamin D supplements – when to take
Best time to take is in the morning. Evening intake could reduce melatonin synthesis since D regulates melatonin production. Low levels of D contribute to poor sleep. Many people take their vitamin D with a calcium-magnesium formula to support the bone health, and this can be done in the evening.
Excess D = toxicity that may lead to high calcium levels (vomiting, muscle weakness, dehydration and kidney stones). Severe toxicity causes kidney failure, irregular heartbeat
This is unlikely to result from food or sun exposure, more likely from extra high doses of D supplements.
VITAMIN D deficiency & Diseases
Autoimmune diseases. Vitamin D deficiency increases risk for autoimmune diseases including MS, lupus, type 1 diabetes.
Low levels also increase the risk of heart disease, infectious diseases, type 2 diabetes and schizophrenia.
Cancer risk includes ovarian and breast, prostate, and digestive system.
Vit D deficiency causes rickets in children and exacerbates osteoporosis in adults. Lower in utero exposure (low maternal intake of vitamin D during pregnancy) increases risk of the baby developing diabetes.
Overall, it appears in practice that many people are deficient in Vitamin D and require some supplementation to keep levels up and protect them for many degenerative diseases. Many of my patients take vitamin D and it is now likely the most commonly prescribed supplement. There’s still much more we need to discover about this vital vitamin.
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