Remember when your Granny swore by Cod liver oil? That's because it's high in Vitamin D and Omega-3 Fatty Acids. In Granny's time it cured Rickets (softening of bones) caused by Vitamin D deficiency.
However, we need to pay more attention to this Vitamin as are more house-bound, in NZ the sun is declining and deficiencies are shown to affect the immune system.
Vitamin D is a fat-soluble vitamin that is not present in many foods, fortified in some foods and produced in the body when UV rays from the sun strike the skin to start Vitamin D3 synthesis. In supplements and fortified foods, Vitamin D is available as D2 (ergocalciferol) or D3 (cholecalciferol). Both forms raise blood serum Vitamin D levels but D3 is more effective as D2 has a lower affinity for binding protein.
Why is this especially important now? Because Vitamin D deficiency is an environmental risk for infectious diseases. This vitamin improves antimicrobial activity of macrophages, the white blood cells that 'eat' viruses.
We already know that in New Zealand, women are below optimal Vitamin D levels (>50nmol/L) from May to November, Children are below May to October while Men seem to obtain enough. As you age, you also process Vitamin D less efficiently in the skin.
Because of both the lack of Vitamin D in foods and sun in winter, it's important to either take a supplement or consume fortified foods and foods high in Vitamin D, such as margarine, fatty fish like mackerel, salmon, herring and eggs. Especially with all of this extra time indoors.
As well as affecting the immune system, Vitamin D deficiency can result in osteomalacia, or weak bones. Symptoms such as muscle weakness and bone pain can indicate low vitamin D levels, but these symptoms can be subtle. Deficiency can also lead to increased bone turnover and osteoporosis.
An acceptable intake for Women:
- 19-30yr 5.0μg /day
- 31-50yr 5.0μg /day
- 51-70yr 10μg /day
- >70yr 15μg /day
An acceptable intake for Children:
- All 5.0μg /day
It's important not to take too much. If you have a bottle and it's in IU, don't exceed 4000IU/day of D in total. Most D supplements are 1000IU/day which is fine. Look out for D3 supplements as these are the best but I purchased a Vitamin D 1000IU recently from the supermarket and this will be fine.
Feel free to take Cod Liver oil...
