What is Vitamin D and why do you need it?
If you are confused about how much Vitamin D to take this winter then this might help.
Vitamin D is an essential nutrient known for its role in helping the body form and maintain healthy bones, muscles and teeth, but the evidence now available shows that it does much more than this. Vitamin D has also been found to play a key role in regulating the immune system, lowering the risk of infection, supporting mood, and reducing the risk of heart disease and autoimmune conditions. Research in this area is still ongoing, but it is such an important nutrient that I think everyone needs to consider how to achieve optimal levels.
Vitamin D was discovered in the 1920s following research into how cod liver oil, a rich source of Vitamin D, could cure rickets. Rickets is a condition in children where bones become weak and soft. It was common in Victorian England but was almost eradicated in the 1940s as foods were fortified with Vitamin D and calcium, and supplements were widely used. Interestingly, since the 1990s there has been a resurgence of the condition, likely driven by modern diet and lifestyle factors.
What food is vitamin D in?
Unlike many other nutrients, it is very difficult to get enough Vitamin D from food alone. While you can get some Vitamin D from eggs and fatty fish, the body’s main source is produced naturally when the skin is exposed to UVB rays from sunlight. In the past, people in the UK may have produced enough Vitamin D in the summer months through outdoor work or daily activities. More recently this has changed, as many people spend most of the day indoors or in cars. Increased use of sunscreen also limits sun exposure and therefore Vitamin D production. You cannot absorb the rays required to make Vitamin D through clothing or when using an SPF of more than 15.
To get Vitamin D naturally without supplements, NHS guidance recommends being in the sun between 11 am and 3 pm for 10 to 15 minutes, three days a week between April and September, without sun protection. If you are not able to do this, the NHS recommends a supplement. They also recommend a supplement for everyone between October and April. Certain groups are likely to need supplements all year round and are at risk of deficiency without doing so:
- Babies
- People who wear clothing that covers most of the skin
- People who use sun protection with SPF 15 or above
- People who spend little time outdoors, including many older adults
- People with darker skin tones, as higher melanin reduces UVB absorption
The reality is that most of us fall into one or more of these groups, so I believe supplements are essential. The question is how much and in what form. It is now easier to understand how deficiencies are returning, with reduced dairy intake, high sun protection use, and more indoor work.
What is the recommended Vitamin D dosage?
The minimum level of Vitamin D in supplements is 400 IU. This is the amount suggested by the NHS, and taking this level along with some sunlight and food sources should protect you against developing rickets.
However, is that enough? Given what we now know about the role of Vitamin D for immune health, mood and bone health, it makes sense to aim for optimal levels.
From the research I have seen and from doctor led papers and seminars, benefits of Vitamin D have been found at supplement levels between 1,000 and 4,000 IU per day. Do not take more than 4,000 IU unless under medical advice, as Vitamin D can be toxic. It is not a case of more being better.
The best way to know how much to take is to have your Vitamin D levels tested. Unfortunately this is not always easy to access through your GP, although they will test if you have certain health concerns. If you are able to, you can share your results with us so we can make personalised recommendations. Alternatively, we can arrange a simple home skin prick test for you (purchase here).
Without testing, we cannot be completely accurate, but there is some helpful guidance:
Suggested supplement range
1,000 IU to 4,000 IU during the winter months.
Supplement at the lower end if:
- You travel frequently over the winter and enjoy 10 to 15 minutes of sun in shorts and a T shirt without sun protection
- You have already been supplementing with 1,000 IU or more throughout the year
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You eat oily fish around three times per week and regularly eat eggs, dairy or fortified foods
Supplement at the mid range if:
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You have white skin tone and had some sun exposure in the UK over the summer without sun protection, but have not previously taken Vitamin D supplements
Supplement at the mid to higher end if you have not taken Vitamin D over the summer and:
- You have darker skin tones
- You have little or no sun exposure
- You follow a vegan diet without fortified foods
- You have a higher requirement for Vitamin D (risk of osteoporosis, menopause without HRT, autoimmune conditions)
What form of vitamin D should you take?
Vitamin D can be taken as sprays, capsules or tablets. The choice is mostly personal, but here are some points to consider.
Vegan Vitamin D
Most Vitamin D supplements found in supermarkets or chemists are from sheep wool, so they are not suitable for vegans. Look for brands that use Vitamin D extracted from mushrooms. We recommend Viridian or TerraNova for pure and ethical vegan options.
Capsules
These are our best selling form and the one we recommend most often because people tend to take them consistently. You must take them with food that contains a small amount of fat, as Vitamin D is fat soluble and absorption is reduced without it. Most people take them at breakfast with milk, yoghurt or eggs.
Shop the capsules:
Sprays
These combine oil and Vitamin D. You spray them into the mouth to support absorption. Studies I have found show similar absorption to oil based soft gel capsules, but they may be superior for people with digestive issues or fat malabsorption. Quality matters, as particle size affects effectiveness. These are convenient as they do not need to be taken with food.
Shop the sprays:
Tablets
I tend not to recommend tablets as they often contain fillers and binders. There is no need for these ingredients in your supplements.
Check the brand
Look for brands with strong ethics and purity standards. Viridian and TerraNova always tick the boxes for us.
Vitamin D with Vitamin K
You may have read that you need to take Vitamin D with Vitamin K, and there is good reason for this, although it is not essential. Vitamin D3 helps your body absorb calcium from food into the bloodstream, and Vitamin K, especially K2, directs that calcium into bones and teeth and away from soft tissues such as arteries or kidneys where calcium build up can be harmful.
There are a few situations where I would always recommend taking K2 with D3:
- If you are taking high dose calcium and Vitamin D supplements
- If you need extra protection for bone or cardiovascular health
TerraNova Vitamin D3 1000iu With Vitamin K2 50ug Complex
TerraNova Vitamin D3 2000iu With Vitamin K2 100ug Complex
Book now for free advice
We know it can be hard to work out the right supplements or dosage, so we offer a free supplement review with a registered nutritional therapist in person or by phone.
Book now: Book a Vitamin D test
The best way to find out your current Vitamin D level is to book a test. All of our health tests include a 30 minute session with a registered nutritional therapist and personalised recommendations.
References available on request.