Vitamin D and Calcium are important for healthy bones, but also for general wellbeing, says naturopath Karen Martin.


What is Calcium & Vitamin D?
Calcium is mainly found in the skeleton or teeth, with the rest stored in the tissues or blood. It is essential for healthy bones, muscles and teeth and plays a vital role in other systems of the body, such as the regulation of muscle, heart and enzyme function and transmission of nervous system messages. Vitamin D is one of the few vitamins that the human body can make itself and has several related compounds-vitamin D3 is the form produced by the human body and is also found in animal products and fish oils, and vitamin D2 originates from yeast and is used in many supplements. Vitamin D is important because it helps the body absorb calcium from the diet, encouraging the deposit of these minerals into bone tissue. Combined, calcium and vitamin D can increase bone density, particularly in the elderly and in post-menopausal women.

Good Sources
Dairy foods are a good source of both calcium and vitamin D. Calcium is found in other foods such as breads, cereals, tinned sardines and salmon, soy and tofu, leafy green vegetables and nuts and seeds. Vitamin D is also found in some foods, including beef, liver, eggs, fatty fish such as salmon and tuna, and fortified foods such as dairy products, but the best source of it is the sun. When the ultraviolet (UV) radiation in sunlight hits our skin, our body is able to convert it to vitamin D3.

How much Calcium?
In the first 30 years of life, our bones are at their strongest which is why getting enough calcium is important in childhood and adolescence. As we age the body loses calcium, and will take what it needs from our bones. The RDI for calcium is at least three serves of calcium-rich foods per day (two to three for children aged five to 11, or 1000 to 1300mg for adults. It is much better to get calcium from your diet, but if you have difficulty obtaining it through food, you may need a calcium supplement, especially if you are at risk of developing osteoperosis. It's a good idea to discuss this with your doctor. If you do take supplements, make sure that you don't take more than the recommended dose as too much calcium may cause gastrointestinal upsets, such as bloating and constipation.

How much Vitamin D?
Because the body manufactures vitamin D, no RDI has been set. Most people should get adequate amounts from sun exposure, but there are some people who should consider supplementation. People who are elderly, institutionalised, hospitalised or get little or no sun exposure on their bare skin are at risk of a deficiency. People with very dark skin require more sun than those with fair skin to generate the same amount of vitamin D (about three to four times as much). People with malabsorption disorders such as Crohn's disease and similar conditions may also suffer deficiencies. Those not exposed to adequate sunlight should aim for a daily oral intake of at least 10ug (400IU) of vitamin D as current expert opinion states that vitamin D supplementation in doses less than 400IU per day is unlikely to have a significant effect on bone health. People aged over 70 years require doses of more than 600IU per day to affect their bone status. You can't get too much vitamin D through sun exposure, however a sensible balance of exposure and sun protection should be found to minimise the risk of skin cancer. Ingesting too much vitamin D3 can lead to toxicity as excess amounts are stored in the body. Prolonged excess intake of supplemental vitamin D3 can lead to increased blood calcium levels (hypercalcaemia), which can cause nausea, vomiting and urinary frequency. If this continues over an extended time, calcification of soft tissue, such as the lungs, kidneys and blood vessels can result.

Interactions & Precautions
Although calcium and vitamin D in supplement form are both considered relatively safe, it is best to consult your doctor as precautions with some drugs and medical conditions are necessary.

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