Vitamin D. The so-called ‘sunshine vitamin’. But not many of us really know what it does, how it’s used or stored within our bodies, or just how important it is.
I’ll admit I knew next to nothing about it until a specialist at the osteoporosis clinic did a simple blood test to discover I was chronically deficient, and probably had been for several years.
How Do We Get It?
Vitamin D can be made naturally in your body in response to sunlight. We tend to get about 90% of our Vitamin D from the sunshine, which isn’t too reassuring if you live in the UK where the sun tends to go into hiding 360 days of the year. To get the benefits, you’d need about 15 minutes of full sunlight, on bare skin, throughout the week. You may get this if you go on holiday somewhere warm and sunny, but this top-up probably won’t last you long enough as it’s stored in the body for around 2 months. Sunscreen also stops the goodness from being absorbed by your skin, so it’s a tricky predicament.
It can also be absorbed from certain foods, but these are quite limited. They include some fortified gain/dairy products, some red meat, egg yolks, and some oily fish. Whilst it’s required by law that manufacturers add Vitamin D to infant formula milk, the added levels in everyday products can vary but are often only tiny amounts.
What Does It Do?
Vitamin D is vital to bone health. We need it because it helps the body absorb calcium (and phosphate) from the diet, which in turn is important for teeth, muscles and bones. In addition, Vitamin D is needed for healthy functioning of your heart, lungs and brain, as well as for fighting infections.
Vitamin D boots your immune system and supports the body’s cells in various ways throughout your life. Your respiratory system, bones, brain, cardiovascular system, immune system and muscles are therefore all aided by Vitamin D.
Once your body grabs some Vitamin D, it gets sent to your liver and turned in to 25(OH)D, which is then redistributed throughout your body. Various tissues then transform it magically into ‘activated Vitamin D’, where it goes on to perform its duties.
Symptoms of Vitamin D Deficiency
Many won’t experience any symptoms, but some may, especially with a more chronic deficiency. At the extreme, it can cause Ricketts, or lead to weak, brittle or thin bones. Some more commonly reported symptoms can include :
- General aches and pains
- Pain in your bones and weakness
- More regular infections (from weakened immune system functioning)
With generalised symptoms, or no symptoms at all, it’s easy for Vitamin D deficiency to go unnoticed or misdiagnosed.
A lack of it has been linked to various problems beyond bones, though research is still up for debate and strong evidence is lacking in many areas. It’s thought it may up the risk of depression, and play a role in migraines and some cancers. My chronic Vit D deficiency is likely to be partly to blame for the osteopenia I now have, being one small step away from osteoporosis at only 27 when I was diagnosed. It can also result in muscle weakness and exhaustion, as if ageing the body simply through the lack of this vitamin.
Am I Likely To Have A Deficiency?
Certain factors can put you at a higher risk of low levels. For instance…
- If your skin doesn’t regularly get sunlight exposure (many don’t because of indoor-based lifestyles or use of suncream)
- If your body needs more than it usually does, ie. during pregnancy
- If you are vegan and unlikely to get many food-based sources
- If you have digestive issues that mean your intestine may not adequately absorb Vitamin D
- If your kidneys aren’t adequately converting Vitamin D into ‘active’ Vitamin D (as often happens in older age)
Should I Supplement?
Always get your level checked first and speak to your doctor about supplementing. Generally speaking, it’s claimed we need 10µg daily (or 600IU if under 70, 800IU if over). For average use and Vitamin D top-up, OTC supplements can be a straightforward way of preventing deficiency. If you have a chronic deficiency, however, you may need to be prescribed a ‘loading dose’, like I did, which is a far greater amount of Vitamin D than any OTC supplement would offer.
A Vitamin D blood test, which looks at the 25(OH)D level, is not routinely done. If you suspect you may be deficient or are experiencing unexplained symptoms speak to your doctor and ask for a Vit D blood test.