VITAMIN D (Calciferol)

“The sunshine vitamin”. Also known as calciferol. Our bodies can produce vitamin D from sunlight’s ultra-violet rays on our skin. Fat-soluble vitamin. Commonly found in foods of animal origin. I also call it “Bone Vitamin No.1’ due to its importance for healthy, strong teeth & bones. (So what is “Bone vitamin no. 2?)

Although we humans can produce vitamin D from sunlight, due to the different pigmentation of people from different descents, the level we can produce vitamin D will vary. A Caucasian will need 20minutes of sunlight, 2-3 times per week to get adequate vitamin D. But a typical African-American with deep skin pigmentation will require double or triple the frequency and duration to get a similar effect.

Please note that frequency and duration will also depend on time of day, season, weather condition (cloudy or sunny) and location (the nearer you are to the equator, the stronger the sun intensity). The sun is at its strongest between 10am to 4pm. It is best to avoid overexposure during this time. A word of warning: chronic excessive exposure to sunlight increases the risk of skin cancer. However there is little evidence that sensible, moderate sun exposure increases the risk of skin cancer. Due to beneficial effects of vitamin D in preventing many cancers, moderate sun exposure may actually guard against cancer.

Because of the health benefits and hazards of sun exposure. Get 10-20 minutes of direct sun exposure (depending on sunlight intensity, skin pigmentation, location) and apply a sunscreen after that, if you intend to be exposed for longer periods.

Vitamin D plays a major role in calcium absorption. The relationship between vitamin D and calcium absorption can be described analogously as “a key and a locked door”. Vitamin D is the key that unlocks the door allowing calcium to leave the intestine and enter the bloodstream. In order for calcium to be effective, we need vitamin D. A vitamin D deficient individual will only be able to absorb 10 to 15 percent of the calcium in their diet. An individual with adequate vitamin D can absorb 30 per cent. 30 per cent does not sound like much, but that is at least double the amount of a vitamin D absorption compared to a vitamin D deficient individual.

30 per cent absorption rate is normal for most healthy individuals, but during pregnancy, lactation and growth spurts (eg. teenagers), the body responds appropriately by increasing the absorption rate to up to 80 per cent.

Vitamin D also works in the kidneys to help retain calcium that would otherwise be lost.

There also is evidence that vitamin D is able to prevent cancer. The highest incidence of colorectal and breast cancer is in areas where people are least exposed to natural light. The dietary form of vitamin D has been shown to inhibit tumour growth. There have been links between breast cancer, prostate cancer, colon cancer and vitamin D deficiency. Studies in the USA and Europe have shown that vitamin D can decrease the risk of getting and dying from colon cancer, prostate cancer, ovarian cancer and breast cancer by 50 per cent.

The active form of vitamin D is ‘activated’ by the kidney, and is called 125-dihydroxy vitamin D. This activated form of vitamin D is responsible for instructing the intestines to absorb calcium from our diet more efficiently, for ensuring our blood calcium is normal thus enabling healthy strong bones.

People who have severe liver problems/disease may have problems absorbing vitamin D (because vitamin D is a fat soluble vitamin, and liver aids in fat digestion).

There has been evidence that obese individuals are prone to vitamin D deficiency. This is due to vitamin D getting embedded deep in the fat tissues and unable to be used effectively by the body.

Vitamin D is also important for proper muscle functioning. A study done in Minnesota by Dr. Plotnikoff during winter, where 150 individuals ranging from children in the early teens right up to seniors of age 65, were complaining of muscle and bone aches/pains. 93 per cent of this group were found to be vitamin D deficient.

There is a concern that the American population (up to 40 per cent) is vitamin D deficient. However, do not go overboard in vitamin D supplementation, as vitamin D is the most toxic of all the vitamins.

Functions/Benefits
Prevents rickets (a disease of growing children – causing softening and deformity of the bones especially those under stress. eg. legs).
Promotes absorption of calcium, iron, magnesium, zinc and other minerals.
Protects against osteoporosis.
May help in the treatment of psoriasis.
Boosts the immune system.
Necessary for strong teeth and bones.
Necessary for proper muscle functioning.
May help to prevent certain types of cancer (colon cancer, prostate cancer, ovarian cancer and breast cancer).

Deficiency Symptoms
Rickets.
Tooth decay.
Osteomalacia.
Bone pain.
Porous bones.
Osteoporosis.
Muscular weakness and spasm.
Stunted growth.
Nervousness.
Lack of vigour.

Natural (food) sources
Fatty fish (herrings, kippers, salmon and tuna).
Liver
Egg yolks
Cod liver oil and halibut liver oil.

U.S: RDA: 10mcg
EU RDA: 5 mcg
Supplementation up to 200-400 IU or 5-10 mcg is ok.
Caution: High doses can be toxic. (Do not exceed 1,000 IUs per day).

Nutrient Destroyers
Mineral oil.

More info >> Nutrient Destroyers

Toxicity
Vitamin D is the most toxic of all the vitamins. Symptoms include: nausea, vomiting, headache and depression, constipation, and anorexia.

More severe symptoms: confusion, high blood pressure, kidney failure and coma.

(Last updated: 16 April 2006)