In recent years, vitamin D has become somewhat illustrious in the vitamin world. It is, or at least should be, high on the priority list of health professionals and the general public alike. Recommendations have been updated a number of times and, as with many things in life, this can get pretty confusing. Cue a handy summary of what’s what in in the sunshine vitamin world, circa 2016-17.

Following the Scientific Advisory Committee on Nutrition (SACN) report in July 2016, Public Health England recommended that everyone >4 years of age should consider taking a supplement containing 10micrograms(mcg)/day vitamin D, particularly during the autumn and winter months. This is because our main source of vitamin D is from the action of sunlight on our skin, which then gets converted in the liver and kidneys to a form that can be used by the body. Nobody is sure exactly how much vitamin D we get from sunshine, hence the recommendation to consider supplementation during those months where the sun is somewhat scarce. I know what you’re thinking…in the UK, the sun doesn’t exactly make a major appearance during spring and so-called ‘summer’ either… But, rest assured, the sun at these times of year has more ultraviolet B (UVB) radiation – even if it is hidden behind layers of ominous clouds – and so this should see you through late March/early April up until the end of September. And no, sunbeds aren’t recommended as a vitamin D top-up!

Nowadays, there aren’t specific guidelines regarding how long you should spend in the sun to get your vitamin D fix, as many other factors influence its synthesis and conversion in the body (such as body fat, muscle mass, skin colour and inflammation status). The National Institute for Health and Care Excellence (NICE) advises that most people can make sufficient vitamin D by going out for ‘short periods’ and only leaving forearms, hands or lower legs uncovered, as these are areas that are often exposed. NHS Choices also advises to:

  • Spend time in the shade between 11.00 am and 3.00 pm.
  • Make sure you never burn.
  • Aim to cover up with a T-shirt, hat and sunglasses.
  • Remember to take extra care with children.
  • Then use factor 15+ sunscreen.

screen-shot-2016-10-07-at-15-07-26We can add to our sunshine source through consuming oily fish, red meat, liver, egg yolks, milk, fortified fat spreads and fortified breakfast cereals. You may have heard of cow’s milk being fortified with vitamin D in other counties, but this isn’t the case in the UK so don’t count on that as part of your daily quota.

Here are a few ideas to get your 10mcg quota (or as near as dammit) of vitamin D in a day:

Day 1

Breakfast: 4 slices of smoked salmon and scrambled egg (made with 2 eggs).

You’re sorted for the day!

Day 2

Breakfast: One bowl of Cornflakes.

Lunch: 2 slices of fortified bread (for example, from Marks and Spencer’s) with fortified spread and egg mayonnaise (can be made just with one egg).

Dinner: Rump steak (with whatever sides you fancy) and fortified yogurt for pud.

Day 3

At whatever time of day you prefer: one grilled herring. Enough said.

Do consider that, if you don’t get enough calcium in your diet, this may adversely affect your vitamin D levels. Aim for 3 portions/day of dairy products (milk, cheese, yogurt). Other non-dairy sources include spinach, figs, curly kale, whitebait, pilchards, sardines, tofu and kidney beans.

Some groups are advised to take a 10mcg vitamin D supplement all year round:

  • People whose skin has little or no exposure to the sun. This may be people who are housebound, living in institutions such as care homes, or those who cover most of their skin when they are outside for religious or other reasons.
  • People with dark skin, for example, from African, African-Caribbean and South Asian backgrounds. It is not clear whether this is due to skin pigmentation, the efficiency of vitamin D synthesis on the skin, or to other physiological or lifestyle differences compared to people with lighter skin colour.
  • Pregnant and breastfeeding women.
  • Children aged 1 to 4 years.
  • Babies under 1 year of age should take an 8.5-10mcg vitamin D supplement daily, unless they are having >500ml of infant formula a day (this is already fortified so supplementation is not needed). So, babies who are exclusively breastfed should be taking a supplement. Supplements for babies come in the form of drops or liquid that can be added to bottles or taken with a syringe or spoon. There is even a spray available on the market for little cherubs who don’t like the taste of the aforementioned options. Women and children with low incomes who qualify for the Healthy Start scheme can get free supplements containing the recommended amounts of vitamin D.

Ensure supplements contain vitamin D3 (cholecalciferol) rather than vitamin D2 (ergocalciferol), as the former is more effective at raising blood levels of vitamin D.

If a healthcare professional has identified you as having low, or even inadequate levels of vitamin D, you may need a supplement that provides >10mcg vitamin D.

Why is vitamin D important?

For infants, children and adolescents, vitamin D is important for healthy bone development in these times of rapid growth. By this, we mean optimal bone mass, i.e. the amount of bone you have, and bone mineral density, i.e. the amount of calcium and other minerals in your bone.

For adults, vitamin D is important to maintain healthy bones and for muscle strength and function.

There are various other conditions that your vitamin D status may influence, such as risk of cancer, cardiovascular disease risk and outcome, low birth weight, hypertension, autoimmune diseases and overall mortality. However, the evidence published so far is inconsistent and thus vitamin D supplementation is not warranted to prevent or treat these conditions.

screen-shot-2016-10-07-at-15-06-45Can I have too much vitamin D?

It isn’t possible to ‘overdose’ on vitamin D from prolonged sun exposure. However, taking high doses of vitamin D supplements, either as a one-off or over long periods of time, may lead to high levels of calcium in the blood. This can actually weaken the bones and damage the kidneys and heart.

Max recommended doses:

Infants under 12 months: max 25mcg/day.

Children aged 1-10 years: max 50mcg/day.

Children aged 11 and over and adults, including pregnant and breastfeeding women: max 100mcg/day.

These maximum upper limits may need to be even lower for people with certain medical conditions that predispose to developing high levels of calcium in the blood, such as normocalcaemic hyperparathyroidism, sarcoidosis, tuberculosis and Idiopathic Intracranial Hypertension.

Take home messages:

  • People aged >4 years old need 10mcg vitamin D from dietary sources or supplementation, assuming minimal sun exposure.
  • It certainly isn’t easy to get your recommended daily allowance of vitamin D from dietary sources. Eggs and oily fish are pretty darn good though.
  • Most people aged 5 years and over may not need to take vitamin D supplements in spring/summer. If you’re doubtful that you’re meeting your daily quota of vitamin D through your diet (see handy hints above), then you should consider taking a supplement in the autumn and winter.
  • If you’re aged 5 or over and (for various reasons…see above) have very minimal sun exposure, you should be taking a vitamin D supplement.
  • If you’re under 5: firstly, I’m VERY impressed that you’re reading this blog post; secondly, ask your mum or dad to get you a vitamin D supplement, unless you’re having >500ml/day infant formula.

natashaNatasha Schoeler PhD

Natasha is a postgraduate student at KCL. She completed her PhD on the genetics of response to the ketogenic diet and is keen to follow a career combining clinical paediatric dietetics and ketogenic diet research.

 

Foodtalk blog posts are written by a variety of health and care professionals in order to showcase different perspectives in the world of nutrition and health.