What is Vitamin D3?


  1. Lots of us have a Vitamin D3 shortage without being aware of it. 36% of apparently healthy young people in the U.S. have too little and as much as 57% of hospital patients are deficient in D3. Some researchers claim as many as seven out of ten older people don’t have enough.
  2. Vitamin D3 is unusual in that we get it mainly not from food but from sunshine. It is produced by the skin on exposure to UVB rays in sunlight. It is known as ‘the sunshine vitamin.’
  3. Vitamin D3 is often referred to simply as vitamin D. Vitamin D2 is also used in the body but D3 is far more useful. (D3 is the type produced by the skin).



1. Vitamin D3 is needed for healthy bones.

Vitamin D3 helps the body to regulate the balance of the minerals calcium and phosphorus, which are both needed by the bones. It does this by aiding their absorption by the intestines.

Deficiencies of D3 can result in weak or brittle bones. This is particularly a problem when a young child is affected at a time when the bones are growing. Secondly, it is a problem in older people, particularly in post-menopausal women, who are in danger of losing bone mass.

2. Vitamin D3 has many functions in the body.

In recent years evidence has come to light that suggests D3 performs numerous vital functions in the body. The most important of these are:

a) Supporting the Heart

There is medical evidence to support this benefit of D3. In hospital trials, patients with cardiovascular disease who took Vitamin D3 supplements had better results.

b) Preventing cancer

People in sunnier climates have lower rates of cancer. Scientists began to wonder if the reason for this was their higher levels of vitamin D3. Evidence from medical research seems to confirm this. For instance, some research published in 2009 concluded that in the U.S. and Canada alone, 58,000 cases of breast cancer and 49,000 cases of colo-rectal cancer could be prevented every year simply by people maintaining good levels of vitamin D3.

However, not all research has supported these results. It will probably be a few years yet before there is enough evidence that is water-tight enough to be publicized by the medical profession. Obviously, this potential benefit is a good reason not to let your D3 levels fall.

c) Preventing diabetes

23 million people in the US have type 2 diabetes and many of them have low D3 levels. Research results conclude that D3 helps prevent diabetes and helps with blood sugar control in those who already have it. However, as with the claims regarding cancer prevention, research is ongoing.

d) Protecting the brain

Vitamin D3 is a hormone-like chemical which acts as a neuro-protector. This means it protects the brain from infections – which can cause damaging inflammation. Many researchers are now convinced that brain inflammation causes many chronic disorders which were until recently regarded as psychological. These include mood swings, depression, panic attacks and obsessive-compulsive disorder.


In the United States, the Institute of Medicine of the National Academies has calculated the minimum daily requirements of vitamin D3 as follows:

Minimum Daily Requirements of D3

Up to age 50 5 micrograms (200 IU)
Age 51-70 10 micrograms (400 IU)
Age 71+ 15 micrograms (500 IU)

Some experts, however, insist that these recommendations are too low. They claim that for the elderly and for diabetics, 30 mcg (1,000 IU) daily is the optimum dose.

In 2008 the American Academy of Pediatrics raised its own recommended levels for babies to 10 mcg (400 IU) daily beginning in the first two months of life, owing to the fact that human breast milk contains virtually no vitamin D3 and that many babies have too little. This recommendation is for all babies, children and adolescents. They assert that this will have life-long benefits.


It is not advisable to take massive amounts of D3: too much can have adverse effects. The recommendations traditionally given for babies under one year old, 25 micrograms is the maximum amount which should be consumed per day. After a year old, 50 mcg will be fine.

The negative effects are a result of D3’s causing an increase in calcium levels in the body. This is a benefit, but only up to a certain level. Too much calcium can be as bad as too little.

However, the only way to absorb too much D3 is to take very large amounts in supplement form. You can never get too much D3 from sunbathing or from food sources.


Vitamin D3 is found in:

  1. Oily fish, such as salmon. Cod liver oil is a good source of D3 as well as of vitamin A and Omega 3 fatty acids.
  2. Foods specially supplemented with D3, including dairy foods, breakfast cereals, margarine and soya products.

Creative Commons's Attribution-ShareAlike 2.5 license

Salmon is a good source of vitamin D3

[Creative Commons’s Attribution-ShareAlike 2.5 license]


1. Not Enough Sun

photo by Nevit Dilmen by CC-BY-SA-3.0 via Wikimedia Commons

Child’s play 21st Century style
(photo by Nevit Dilmen by CC-BY-SA-3.0 via Wikimedia Commons)

We simply do not get enough ultra-violet radiation (UBV) from sunlight any more. Children, who a generation ago would have spent most of their time outdoors, are now ensconced in their bedrooms playing on computers. Even if children would like to play in the street, in many locations parents regard this as too dangerous.

2. Use of Sun Blocks

We also use sun blocks to protect ourselves from skin cancer; at the same time the sun block prevents production of D3 in the skin. The helpful UVB rays are blocked along with the harmful UVA rays.

We use sun block to prevent skin cancer, but it also prevents D3 production

Sun block – both helpful and harmful.

3. Ethnic Dress

justin hall at http://flickr.com/photos/35034345586@N01/35234428 {cc-by-SA-2.0]
The Burka prevents sunlight reaching the skin

(justin at

In some parts of the world some ethnic modes of dress, such as the Muslim burka, cover the entire body leaving virtually no exposed skin to benefit from sunlight. It is vital in these circumstances to ensure the diet is high in D3 or to take supplements.

4. Kidney or Liver Problems

D3 must be processed by the liver and/or kidneys. Those who have damage to either of those organs may have enough D3, but it remains in a form the body cannot use. As it is a fat-soluble vitamin, it has to be stored in the liver, too. Alcoholics, who have highly-stressed and damaged livers, often cannot process D3 and lose bone strength as a result.

5. Conditions which Affect Digestion

People who have a condition which lessens their ability to absorb and process fats – for instance, cystic fibrosis – can have limited ability to process any fat-soluble vitamin such as D3. Inflammatory intestinal conditions, such as colitis and Crohn’s disease, can also reduce the ability to absorb vitamins. People in these categories need to ensure they get enough exposure to sunlight. Ten minutes each day is said to be enough to prevent deficiencies, even in northern climates. Failing that, sun-beds can be used.

6. A diet low in D3

Some ethnic diets do not naturally contain significant amounts of vitamin D3. Sunlight enables a person with darker skin to produce enough D3 in a hot country, but migrating to colder climates can result in a shortage. For example, worrying numbers of cases of rickets were recently found in children of Pakistani immigrants living in the north of England. Their rice-based diet did not include enough butter, margarine or oily fish to compensate for the lack of sunlight.

In the wider population generally poor diets, such as junk food diets, do not contain sufficient vitamins of any kind.


1. Rickets and Osteomalacia

Rickets is the result of D3 deficiency in young children. The bones do not develop with sufficient strength and this results in their bending under the weight of the body, giving the appearance of “bow-legs” or “bandy-legs”. Rickets was common in the 19th and early 20th Centuries, notably in industrialized regions where air pollution from factories often blocked the sun whilst poverty resulted in low-quality diets. Osteomalacia is the adult form of rickets.

Boy with rickets

Boy with rickets.
By Umeedhom (Own work) [CC-BY-SA-3.0] via Wikimedia,com

2. Osteoporosis

Osteoporosis is a progressive weakening of the bones caused by a reduction in hormone levels in later life. It has long been known that it afflicts post-menopausal women, but it is now come to light that considerable numbers of men are affected as well. It can also affect sufferers from anorexia nervosa.

The bones lose density and become weak, brittle and easily broken. As the body requires D3 to process calcium, lack of this vitamin renders the condition worse, sabotaging the body’s attempts to retain bone mass. The disease can cause a stoop or a “dowager’s hump” (hyperkyphosis) owing to the bending of the spine.

Japanese woman with osteoporosis

Japanese woman with osteoporosis
Photo James Heilman, MD [CC-BY-SA-3.0]

3. High blood pressure (hypertension)

Research shows that D3 plays an important role in regulating blood pressure. Hypertension is much rarer close to the Equator than in more northerly climes where there is less sunlight.

Vitamin D3 lowers blood pressure by preventing the excess production of a chemical called angiotensin II. This chemical not only raises blood pressure but can cause thickening in the heart and artery walls and a rise in stress hormones. Before this research was done, expensive drugs, which often had unpleasant side-effects, were the only means of controlling it.

Calcium is also known to reduce blood pressure. Without vitamin D3, the body can’t use calcium.

4. Heart problems

Research shows that a deficiency of Vitamin D3 produces stiffness and inflexibility in the blood vessels. D3 influences the function of muscle cells and reduces inflammation in the arteries.

5. Depression and fatigue

Insufficient D3 can lead to low moods, tiredness and weakness. It may contribute to the condition known as S.A.D. (seasonal affective disorder), which causes people to become depressed during the winter months owing to the lack of sunlight.


Vitamin D3 is now known to modulate the immune system and influence the expression of numerous genes. This means that its functions in the body are complex and wide-ranging. While research is ongoing, it is now apparent that D3 is of immense importance to health. Since low grade deficiencies can so easily go undiagnosed, it’s wise to use sun or supplements to ensure you get enough.