2022 marked one hundred years since two biochemists reported their discovery of a substance they would name Vitamin D. Whilst it has long been known for its importance in supporting bone health, there has been an explosion of recent research about the significance of Vitamin D in relation to a range of other types of health including brain and immune health. Vitamin D is now the most highly researched nutrient so you may have seen lots of information flying around in the media about the ‘sunshine vitamin’ and the implications for deficiency. However, I think there are still some misconceptions about this important vitamin and if you want to make sure you are getting enough then there are a few things you need to know.
What is Vitamin D?
Vitamin D is actually more appropriately classified as a hormone rather than a vitamin given its production, actions in the body, and the fact that all non-skeletal cells in the body have Vitamin D receptors (a sure-fire clue as to why it is so important). It’s called the sunshine vitamin because the majority of our Vitamin D is produced in the body from a form of cholesterol stored under the skin. However, what you might not know is that the UVB radiation from the sun required to stimulate this production is only strong enough in the UK from April to September. From October to March the radiation from the sun is not strong enough to stimulate this production as the sun is not high enough in the sky. An easy way to tell whether the angle of the sun is sufficient is to check your shadow – the length of your shadow needs to be shorter than your body, if it’s not then you won’t be able to make Vitamin D.
There are two forms of Vitamin D – D 2 and D 3 . D 3 is the form produced under the skin and is found in animal products. Consequently, this form of Vitamin D is the most bioavailable. D 2 is formed in fungi and yeast on exposure to UVB and is typically the form of Vitamin D used in supplements and fortified foods. However, D 2 is not well absorbed or utilised by the body. In order to be biologically active in the body these molecules are then converted in the liver and kidneys to the active forms. All the enzymes involved in these processes require magnesium to function, so if we are not getting enough magnesium in our diet, we may be unable to make use of the Vitamin D. The full activity of Vitamin D also requires other important cofactors such as Vitamin A, B2, zinc, selenium and essential fatty acids. Therefore, it is useful to think about the overall nutritional profile of the foods containing Vitamin D to help us make the most of our intake.
The importance of Vitamin D
Sufficient levels of Vitamin D can bring about many benefits to teeth, bone, and muscular health. It has long been known that Vitamin D is needed for normal growth and development of bone in children. In older individuals, it helps to reduce the risk of falling associated with postural instability and muscle weakness and the likelihood of bone fractures. This is because Vitamin D plays a critical role in the absorption and utilisation of essential minerals such as calcium, phosphorus, and magnesium.
However, research has increasingly shown a much wider range of health benefits associated with adequate Vitamin D that goes beyond its role in skeletal health. Over the years Vitamin D has been positively associated with reduced inflammation, autoimmune disease, and allergies due to its role in the normal functioning of the immune system. As well as improved mental and emotional health, gut health, health during pregnancy, and hormonal health. Multiple studies have also shown the importance of Vitamin D in reducing insulin resistance and the consequent development of diabetes and obesity.
Getting sufficient Vitamin D
Sun exposure from April to September is the best way to ensure we are getting enough Vitamin D. The body can store Vitamin D so if we get outside enough in the summer months, we can draw on our reserves from October to March. However, our modern lifestyles often mean that we don’t build up our reserves, so we also need to think about other sources of Vitamin D.
Current government recommendations are for a daily intake of 10 micrograms (µg) or 400 international units (IU) of Vitamin D throughout the year for anyone over 4 years old, but when it comes to eating enough ‘D is for difficult’. There are very few rich sources of Vitamin D, but the best ones are oily fish, liver, red meat and egg yolks. Mushrooms exposed to UVB are another food source, but you would need 2kg a day. Some products such as milk, fruit juice and breakfast cereals are fortified with Vitamin D but at very low levels and in the form of D 2 which is not well utilised by the body. Given how difficult it is to achieve this intake from food sources alone, a supplement is a good idea for most people particularly through the winter months. However, our supplementation needs are very individual, and it is probably worth getting some advice on the best way to determine what they are.
So from a practical perspective here’s the bottom line. Get out in the sun for 15mins around 12pm from April to September, eat as many rich food sources as you can regularly and take a daily supplement at least through the winter months, if not all year. Plus, make sure you have sufficient magnesium to convert it for use in the body.
Our understanding of the importance of Vitamin D to our health and the way it operates in the body has come a long way in recent years. Having sufficient levels of this key nutrient is fundamental but our requirements will vary according to our individual circumstances. Therefore, a tailored approach to nutrition and lifestyle is likely to support optimum health. If you or someone you know is looking for an individualised approach to support their health, well-being and energy levels then use this link to book in for a complimentary 30-minute health and energy review.