Yes, it’s true our exposure to sunlight, given the right season and enough time in the sun, has an important role in determining our Vitamin D status. With the help of sunlight, vitamin D is synthesized by the body from a precursor derived from cholesterol. Vitamin D exists as either vitamin D2 (ergocalciferol) or vitamin D3 (cholecalciferol). The active from of vitamin D is actually a hormone that targets organs – most notably the intestines, kidneys, and bones. In the intestine, vitamin D is involved in the absorption of calcium and phosphorus. In the bone, it assists in the absorption of calcium and phosphorus, helping bones grow denser and stronger as they absorb and deposit these minerals.
Why is Vitamin D Important?
One of the main roles of vitamin D is to facilitate the absorption of calcium and phosphorus. Consequently, a vitamin D deficiency creates a calcium deficiency, with significant consequences to bone health. Among children and adolescents, it may cause rickets and adversely affect peak bone mass. In adults, vitamin D deficiency increases the risk of osteomalacia and osteoporosis.
Sources of Vitamin D
Sunlight – exposure to ultraviolet B (UVB) rays is necessary for the body to synthesize vitamin D from the precursor in the skin. It’s not known exactly how much time is needed in the sun to make enough vitamin D to meet the body’s requirements. This is because there are a number of factors that can affect how vitamin D is made, such as your skin colour or how much skin you have exposed
Natural food sources of vitamin D include red meat, liver, egg yolks, and oily fish such as salmon, sardines, herring, mackerel and fresh tuna. A selection of fortified foods from fat spreads and choice breakfast cereals may be available at the market.
Bioavailability of Vitamin D
There is very little information on the bioavailability of vitamin D. It is assumed that the food matrix has little effect on absorption. Bioavailability also varies among individuals and depends on the level of circulating vitamin-D-binding protein.
What Influences our Vitamin D Status?
Inadequate exposure to sunlight is the primary risk factor for poor vitamin D status. The use of sunscreen, higher levels of melanin in skin (i.e., dark skin), skin coverings (clothes, veils), and time of day are factors that decrease exposure to UVB rays. The distance from the equator is also a factor for UVB exposure; people living in latitudes above or below 40 degrees from the equator will be unable to form vitamin D from the skin precursor during the winter months.
Breast milk is a poor source of vitamin D. Children who are exclusively breastfed and have no or little sun exposure require vitamin D supplements to meet requirements.
Remember! While sunlight is important for our vitamin D levels be careful not to burn in the sun. Take care to cover up or protect your skin with sunscreen before your skin starts to turn red or burn.
Download our complete vitamin and mineral guide here.
Here is a recipe to easily incorporate Vitamin D rich foods in your diet!
Salmon Fish Cakes*
450g floury potato (cut into chunks)
350g salmon ( 3 fillets)
2 tsp tomato ketchup
1 tsp English mustard
½ lemon zest grated
1 heaped tbsp chopped parsley
1 heaped tbsp chopped dill
3 tbsp plain flour
1 egg beaten
100g dried breadcrumb
4 tbsp sunflower oil
1. Heat the grill. Place the potatoes in a pan of water, bring to the boil, cover and cook for 12-15 mins until tender. Drain and leave to steam-dry, then mash. Meanwhile, season the salmon and grill for 5-6 mins until just cooked. Cool for a few mins, then break into large flakes.
2. Mix the potato, ketchup, mustard, zest, herbs and some seasoning. Lightly mix in the salmon, taking care not to break it up too much. Shape into 4 large fish cakes.
3. Put the flour, egg and breadcrumbs in 3 shallow dishes. Dip the cakes into the flour, dust off any excess, then dip in the egg, and finally coat in breadcrumbs. Heat the oil in a large pan. Fry the cakes over a medium-low heat for 3-4 mins each side until deep golden and heated through. Serve with salad and lemon wedges.
*Adapted from BBC Food Recipes online