(calciferol, cholecalciferol or ergocalciferol)
For most of human history Vitamin D came from the sun but as people moved away from the equator and spent more time indoors vitamin D deficiency became a problem. When the sun hits our skin it turns sterols into vitamin D. The amount made is regulated by our skin colour - dark skin people make less because of the melatonin which blocks the production. From an evolutionary point of view this is because dark skinned people tended to have lots of sun exposure living closer to the equator where fair skinned people had less.
Vitamin D is essential for maintaining calcium levels in the blood and getting calcium to our bones and teeth. It also has roles in the immune system, muscle function, brain, pancreas and thyroid. Animal products with vitamin D are fatty fish and eggs . Back when rickets (soft bones that don’t develop properly in children) was a terrible debilitating condition, people experimented to find the cause. It was found that both UV therapy and a dietary element could cure this disease. This lead to the discovery of vitamin D. Vitamin D production in food was first found when mushrooms, yeasts and alfalfa were exposed to sunlight. This lead to the vitamin D fortification of cows milk and infant formula.
The daily value for vitamin D is variable but is around 10mcg (400 IU).
Those at risk of low vitamin D
Dark skinned people with little sun exposure
House bound people
Those individuals with severe kidney/liver disease
People who wear clothing covering most of their bodies for religious reasons
Anybody in winter who has very little sun exposure e.g those living in the South Island of New Zealand.
Vitamin D tips
Find a milk alternative or breakfast cereal that is fortified with vitamin D e.g Sanitarium So good soy milk, Vitasoy oat milk ‘bone health.
Spend some time in the sunshine and it will make you happy. To make adequate vitamin D a light skinned person needs around 10-15 minutes of midday sun exposure, dark skinned people need 20 minutes and older people need up to 30 minutes.
Wild mushrooms or UVB exposed mushrooms can be a source. It should be noted that most mushrooms available in supermarkets are grown indoors and are not a good source of vitamin D).
Take a vitamin D supplement in the winter especially if you work indoors or are in the South Island of New Zealand.