Some of the contributing factors for this increase in Vitamin D deficiency include;
- Sun cream and our sun avoidance (although I know it is a necessity to some at certain times of the day)
- cloud cover
- certain disease states including; inflammatory conditions and obesity and
- Melanin affects the production of Vitamin D. So those with more melanin, or darker skin, produce less Vitamin D than someone with fair skin
- Wear clothing that covers most of your body
- Take medications that interfere with vitamin D production.
- Have a condition that affects the absorption of vitamin D- such as crohn’s or coeliacs disease
Vitamin D is also known as the sunshine vitamin as it is synthesized by the action of sunlight on the skin. Vitamin D plays an important role within the body. It is needed for Bone growth, tooth function and for calcium and phosphorus absorption reducing the risk of fractures.
It also plays a role in calcium metabolism and protein production making it essential to correct muscle function. This also impacts on the body’s ability to repair and regenerate after training sessions and prevent injuries.
For a runner after intense exercise the rate of inflammation within the body increases due to the elevated levels of pro- inflammatory cytokines. Vitamin D assists in the reduction of these cytokines while producing more of the anti inflammatory type- this clever vitamin therefore has the ability to speed up the recovery process between races and returning to training or even just between hard training sessions.
Studies conducted in Vitamin D deficient subjects showed that when supplemented with vitamin D both the content and size of their type II muscle fibres as well as the muscle strength increased. These are key points for an avid runner.
Our immune system also requires vitamin D as it enhances the immune response both virally and bacterially. It is a vital nutrient in helping protect against autoimmune diseases. It also aids in reducing inflammatory conditions such as MS, inflammatory bowel disease, Rheumatoid Arthritis, asthma and Diabetes. Research has shown that this vitamin is also important for maintaining healthy blood sugar levels. It is thought to be involved in both insulin secretion and insulin sensitivity. It is also a noted nutrient is some cancer prevention (breast, colon and prostate).
Studies have shown that runners with a reduced vitamin D status tend to have more colds and flu’s each year and this can be the determining factor between the delicate balance of a heavy training schedule and staying healthy for the season.
Vitamin D also assists with healthy functioning of our nervous system and neuromuscular function. It is necessary for the nerves to carry messages between the brain and the body. Vitamin D is involved in numerous brain processes, making it biologically likely that a deficiency in this vitamin might be associated with depression and that its supplementation may play an important part in the treatment and prevention.
Vitamin D is involved in the regulation of cholesterol within the body. It is thought without adequate sun exposure the body converts the vitamin D precursors into cholesterol rather than vitamin D thus increasing cholesterol levels. It also plays a role in reducing blood pressure- this is very important as we age.
What is considered an optimal level of Vitamin D
Current ideal levels of serum 25–hydroxy-Vitamin D (25(OH)D) are thought to be greater than 50 ng/ml for optimal performance and at least above 40 ng/ml for ‘normal’. Once the body drops below this level any vitamin D that the body gets (through food or sunshine) is used primarily for day to day metabolic needs.
Food sources of Vitamin D include
- egg yolk
- sprouted seeds and
- fish liver oils such as cod, halibut, herring and tuna, beef, liver
If you have any doubts about your vitamin D status a simple blood test to check your Check for total 25(OH) D (which reflects all sources of Vitamin D – from food, UV energy and photo-production) will confirm your status. Everything in moderation- Not too much nor too little.
Signs of vitamin D toxicity are often associated with increased blood levels of calcium and can include: Nausea, vomiting, poor appetite, weight loss, constipation, weakness, confusion, disorientation, and problems with heart rhythm.
It is best not to supplement until you have checked your Vitamin D status.
For more information check with your Nutritionist/Dietician or Health practitioner.