How much Vitamin D is enough and how much is too much?


Understanding Vitamin D dosage recommendations

What is the Governments advice?

The Government in the UK has issued public health advice stating that everyone should consider taking Vitamin D supplements in Autumn and Winter. The dosage recommended is 10 micrograms (400iu) of Vitamin D per day. There is concern that is may not be achievable through diet and sunlight alone and people should therefore get their Vitamin D intake from supplements.

Can’t I get this from my diet or from the sun?

Limited amounts of Vitamin D are found in foods such as oily fish, eggs and fortified foods but for most people, the majority of their Vitamin D is made from the action of sunlight on their skin. Since we have a lack of sun for the most part of the year in the UK, there is a real concern that people just aren’t reaching the optimum levels necessary for good health.

What should my levels be?

Vitamin D levels are checked by a blood test. Vitamin D is measured in nanomoles per litre (nmol/L). You can ask your GP for a Vitamin D test or order a home test kit from the Vitamin D Council - www.vitamindcouncil.org.

The UK Department of Health advises the following measurement guidelines:

  • >50nmol/l = adequate
  • 25-49nmol/l = insufficient
  • <25nmol/l = deficient

We do know that the majority of people in the UK fall into the deficient category.

How much should I be supplementing with?

You may have had your Vitamin D levels tested or you may strongly suspect that you are deficient and you want to boost your levels. What dosage should you take?

The answer to this is quite complicated due to the difference between all our lifestyles. How long to you go out in the sun for? How often do you eat oily fish? Do you use a total block sunscreen, what are your current Vitamin D levels etc. We know that the minimum you should be taking is 10mcg (400iu). For this reason all our top multi vitamin and minerals contain this amount. However this dosage may not be enough for people who are deficient or those who may be in the “at risk” groups. These people need to be more careful about ensuring they get a good intake of Vitamin D. Those considered to be in the “at risk” group are –

  • Infants or children aged under 5
  • pregnant and breastfeeding women, particularly teenagers and young women
  • people over 65
  • people who have low or no exposure to the sun, for example, those who cover their skin for cultural reasons, who are housebound or confined indoors for long periods
  • people with darker skin, for example, people of African, African-Caribbean or South Asian family origin

All things considered, a daily Vitamin D supplement intake of 25 – 100mcg (1000 – 4000iu) should be enough to ensure good blood levels in most people.

How much is too much?

We don’t need to worry about taking too much Vitamin D through our diet as the amounts are minimal. We also don’t need to worry about getting too much from the sun as the body has a feedback mechanism that prevents too much Vitamin D from being made through the skin. Vitamin D toxicity can however occur through overuse of supplementation. This is known as hypervitaminosis D. It is exceptionally rare and usually occurs in extremely high long-term doses of Vitamin D supplements. The main consequence of Vitamin D toxicity is a build-up of calcium in your blood. The Institute of Medicine and HFMA (Health Food Manufacturers Association) recommend the upper safe limit of 100mcg (4000 iu).

Be wary of buying a Vitamin D supplement online which is higher than this dosage and does not give any mention of guidelines. If you are considering taking a higher dosage than 4000iu, please speak to your Doctor before purchasing.

How can I find out more?

If you have any further questions about your Vitamin D dosage, why not ring our team of Nutrition Advisors who can answer your queries. Simply call them on 01892 55 21 75 between 9 and 5 during the week. Please leave a message outside of these hours and they will get back to you or email them your questions in the “free nutrition advice” section of our website.
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