Vitamin D is known as the ‘sunshine vitamin’ as large quantities can be produced by the body when skin is exposed to UVB light.
As the daylight hours shorten and we start to spend more time wrapped up indoors, we should start to think about our vitamin D levels and how to keep ourselves topped up throughout the winter months.
1 in 6 adults in the UK are estimated to have insufficient levels of vitamin D in their blood (1). Vitamin D deficiency, although common, can go undetected, brushed off as “the winter blues” or “the change in season”. Symptoms may include one or more of the following; feeling fatigued, experiencing low mood and depression, joint and muscle pain, hair loss and suffering from frequent colds and infections.
Vitamin D is a vital nutrient, involved in the functioning of every system in the body, and yet many of us are running on suboptimal levels and need a boost!
Where does vitamin D come from?
The body makes a form of vitamin D when skin is exposed to sunlight and this is the primary natural source of vitamin D production. This is sufficient for some throughout the warmer months, however if you have dark skin or cover up most of your skin with clothes, then production will be less.
The UVB rays that Northern Europe receives during the months of November-March are too weak to result in adequate vitamin D synthesis. This means the skin makes very little vitamin D throughout the winter, leaving us vulnerable to suboptimal levels.
Some people may be especially vulnerable to deficiency, including:
- Vegans and vegetarians
- Pregnant and breastfeeding women
- Individuals with dark skin or skin that’s mostly covered
- People with digestive impairments, such as Inflammatory Bowel Disease (IBD) or fat malabsorption disorders.
- The elderly (65 years and older). Vitamin D synthesis in the skin becomes less efficient as we age.
- People on medications that can deplete vitamin D status e.g., statins and steroids.
Can we get enough vitamin D from food?
Food sources of vitamin D include oily fish (e.g., sardines, anchovies), egg yolks, liver and some types of mushrooms, as well as fortified foods (cereals, milk etc).
As a nutritionist I love to use food first as the source of nutrients. However, when it comes to vitamin D, food sources don’t quite cut it. They don’t contain enough of the nutrient to be able to maintain adequate levels without the help of summer rays, especially if you are avoiding animal products.
The role of vitamin D – Why do we need It?
Many of us will have grown up being told that vitamin D is the nutrient needed for healthy bones and muscles but it has since been discovered that its role in our overall health goes way beyond this!
Vitamin D supports the:
- Immune system – helps defend the body when tackling viral infections, illness and is important for respiratory health. Vitamin D is also supportive in autoimmune diseases.
- Endocrine (hormone) system – minimises the risk of type II diabetes.
- Reproductive System – is important for women’s health (fertility, pregnancy, breastfeeding, perimenopause and menopause).
- Nervous System – helps to regulate mood, reduce anxiety and relieve symptoms of depression.
- Cardiovascular System – helps to regulate blood pressure and may reduce the risk of heart attack and cardiovascular disease.
- Musculoskeletal System – is important for calcium absorption and helps to maintain good bone and muscle health.
Should we supplement with vitamin D?
Taking a daily vitamin D supplement could be a simple way of improving your health this winter and beyond. The question is, how much do you currently need for your body to be well supported?
The UK government advises adults and children over the age of 4 take 400 IU (10 micrograms) throughout the months of October to March. Individuals with dark skin, women who are pregnant or breastfeeding and those who lack sun exposure, are advised to take 400IU all year round (2).
Please note: Some people have medical conditions that mean they cannot safely take this much vitamin D. If in doubt, you should consult your doctor.
For the majority of the population, these measures will prevent deficiency (blood levels less than 25 nmol/L [10 ng/mL]). However, the reality is that for most people, 25 nmol/L isn’t enough for optimal wellbeing. It is suggested that optimal levels require a blood concentration of more than 75 nmol/L (30 ng/mL) up to 125 nmol/L (50 ng/mL).
What dosage should I take?
How much you require will depend on your current level and circumstances. Unfortunately, there isn’t a magic number for everyone. It is always best to test first, either via your GP or with a registered nutritional therapist. This is because vitamin D is a fat soluble vitamin, meaning the body is capable of preserving stores in the liver and therefore you can take too much.
If you would like help establishing your vitamin D level, amount to take and a good quality supplement, along with diet and lifestyle recommendations to support your immune system and other aspects of your health, please get in touch HERE