Vitamin D: How much is enough?

 

BY ISABELLE NUNN, Head of Nutrition at Wild Nutrition.

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1 in 6 of us in the UK are estimated to have insufficient blood levels of Vitamin D for good health; we simply can’t produce enough of it from the sunshine alone, especially those of us in Northern Europe. The half-life of this vitamin is also only 3-6 weeks, so even gathered stores over the summer rapidly decline by deep winter.

 

How much Vitamin D do I need to take?

Aside from sunshine helping us reach optimal Vitamin D levels, certain food groups can also offer further support including: 

• Oily fish (salmon, trout, sardines, mackerel) 
• Whole-fat dairy
• Egg yolks
• Red meat
• Fortified food.

However, only 10% of the required intake can be achieved via diet alone. So, if you don’t or rarely consume them, then you won’t even be hitting this. The Department of Health recommends the following guidelines and supplementation for those below:

• Adults
• Teens
• Babies & children
• Women navigating fertility, pregnancy or breastfeeding.

Adult Vitamin D requirements  

All teens and adults should supplement 10ug (400iu) every day between October to spring (the official month is March, but common sense should be applied, since sunshine ‘quality’ can vary year on year). If you're over 65, the recommendation is that this dose is taken all year around - especially if you're indoors more, not exposed to consistent sunlight or experiencing illness. 

All pregnant, breastfeeding women and at-risk groups (such as people from ethnic minority groups with dark skin, elderly people in care homes and those who wear clothing that covers most of the skin) should take a daily supplement containing 10 micrograms (400iu) of Vitamin D all year round.

However, it's important to consider that many people in the UK do not get good access to consistent sunlight due to work (offices) and 'typical British' summer weather (cloudy days and rain).

Please speak to a health professional if you feel you need to take additional Vitamin D over the recommended levels, especially if you have received results that show you are below the optimal range or deficient, or you're experiencing any ongoing challenges to your immune system as you may be professionally recommended to supplement with more than 10ug.

Teens & Vitamin D

Vitamin D is an essential nutrient for developing teens. Research shows low Vitamin D levels are very common in adolescents, which is a concern as this is when the skeleton grows the most rapidly of any life stage. 

Therefore, they may be ‘using up’ their Vitamin D levels for their bones, and require Vitamin D to sufficiently support their immune system. Their developing immune system may fluctuate more than an adult's, as they're prone to higher levels of inflammatory cytokines (immune chemicals).

Teens low in Vitamin D should be evaluated for supplementation as young adults rather than children. They're frequently incorrectly viewed nutritionally as ‘bigger children’.

Babies & children

All babies from birth up to one year of age should take 8.5 to 10 micrograms (340iu to 400iu) of Vitamin D per day (particularly those being breastfed). Babies fed infant formula will not need vitamin drops until they're taking less than 500ml (about a pint) of infant formula daily, as these products are fortified with Vitamin D.

While children between one and four should take 10 micrograms of Vitamin D (400iu) supplements all year round. However, for babies, toddlers and older children who do not consume Vitamin D-rich foods, professional health advice is recommended. 

 

Fertility, pregnancy & breastfeeding 

Official UK government advice states that women who are pregnant or breastfeeding require 400 IU (10ug) of Vitamin D to be supplemented.

Please seek advice from a health professional if your current levels are less than optimal, low, or you're deficient, especially in the colder and darker months. You are also more at risk of low levels if you spend greater amounts of time indoors (even in the summer), or have darker skin or cover up your skin. 

If you're already pregnant, you need to make sure you're supplementing at least the officially recommended dose for both your own health and your baby’s (who draws upon your reserves for its growth and development). If you didn’t know this, you may need to catch up on dosing, so please do reach out to your doctor to discuss safe supplementation. 

NHS testing for pregnant women does not usually happen before the first midwife appointment, and sometimes later, at around 8 to 12 weeks. So if you are concerned, book an appointment with your doctor sooner. 

If you're trying for a baby, Vitamin D levels may not be optimal overnight. Knowing your Vitamin D levels in advance will help you plan supplementation. The preparations you make in this phase will help support a healthy immune system, bones and teeth throughout your pregnancy. 

We recommend getting your levels tested (via a blood test), and if you're undergoing assisted fertility, such as IVF, we recommend getting levels checked in advance of any procedures or medical treatments. Please note that some fertility clinics do not check Vitamin D levels as standard, so be sure to request this or check with your usual GP, IVF clinic or other official Vitamin D test provider. 

Breastfeeding women are, of course, sharing some of their Vitamin D stores via their milk, so supplementation is key in this stage too. Even if you don’t breastfeed, supplementation should still be considered, especially if you've just given birth, as deficiencies are common due to delivery (blood loss, healing time, impact on the immune system through lack of or broken sleep).

 

Can I get Vitamin D through a window? 

It's worth noting that while you can get a tan through glass, you cannot access the special UVB rays needed to produce Vitamin D. 

What about Vitamin D toxicity?

Vitamin D toxicity is rare. A person would need to be taking very large doses over a long time. The real modern risks are Vitamin D insufficiency and deficiency. If you are at all concerned, speak to your health care provider. 

In terms of what the right dose is for you, we always recommend speaking to an expert and considering having your levels checked. We'd be happy to guide you further, book a free 15-minute consultation to speak with our nutritional team today.