Author: Rob Hobson Category: Health, Men's Health, Supplements & Vitamins, Women's Health
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Why do I need vitamin D, should I take a supplement and if so how much?

Rob Hobson, registered nutritionist and head of nutrition at Healthspan, explains why this vitamin is so important and why supplements may be the only option during the winter months.

Vitamin D has been a sexy nutrient for a while now and research findings exploring its many potential health benefits seem to make the headlines on a monthly basis.  So, what does it do, how much do we need, and can we get enough from our diet or do we need to take a supplement?

What is vitamin D and what does it do?

The main role of vitamin D is working with calcium and phosphorus to help maintain healthy bones and teeth.  Contrary to most people’s knowledge about bone health, vitamin D is more important in this role as it’s essential for the absorption of calcium in the body.  As well as protecting the body from bone disorders such as rickets and osteomalacia (softening of the bones), this nutrient also helps to maintain muscle strength. 

There’s good evidence from scientific research to show that vitamin D plays a key role in immunity by reducing the risk of coughs and colds.  It also appears to be important for preventing depression such as Seasonal Affective Disorder (SAD), which affects a small percentage of the population.  Other studies have suggested a role of vitamin D in conditions such as diabetes, asthma, multiple sclerosis and breast cancer but more research is needed in these areas. 

How much vitamin D do you need?

Advice from Public Health England (PHE) says that adults and children over the age of one should have 10 micrograms (mcg) of vitamin D every day.

Those at the greatest risk of vitamin D deficiency include:

  • Babies and young children, and children and adolescents who spend little time playing outside
  • Pregnant women and breastfeeding mothers
  • People over 65 years old because their skin is not as good at making vitamin D
  • People with darker skin tones – that is people of Asian, African, Afro-Caribbean and Middle Eastern descent – living in the UK or other northern climates
  • If you always cover most of your skin when you are outside and the further north, you live
  • Anyone who spends very little time outside during the summer – the housebound, shop or night shift workers

Findings from the UK National Diet and Nutrition Survey have shown from blood analysis that there’s evidence of low vitamin D status in 23% of adults and 22% of teenage children over the year but that this increases to 40% amongst all age groups during the winter months.

What if you don’t get enough vitamin D?

Many of the potential symptoms of vitamin deficiency are unlikely to occur unless you have very low intakes over a prolonged period of time, but this is perfectly viable for many people given the findings from the NDNS survey and the nature of those most at risk of deficiency in the UK.

Aching bones

Vitamin D is essential for supporting bones and their structure.  This nutrient helps regulate calcium and phosphorus – the minerals essential for maintaining strong bones – within the body.

When you’re low on vitamin D, your bones can weaken, increasing your risk of stress fractures and putting you at greater risk of conditions such as osteoporosis (brittle bones), rickets and osteomalacia (soft bones).

Muscle weakness

As well as bones, vitamin D also supports normal muscle function and deficiency is thought to be linked to muscle pain. A study published in the British Medical Journal has shown that poor muscle strength and weakness may be associated with vitamin D deficiency, which is common among older people because their capacity to synthesise vitamin D through the skin decreases with age.

Lack of sleep

Although conducted on a small group of people, an American study has suggested a possible link between low levels of vitamin D and poor sleep.  The study that involved a group of older men showed that those with lower levels of vitamin D appeared to report not only less sleep but also poor-quality sleep. These findings can be supported by other studies that show patients with hypoparathyroidism (people who have low levels of Vitamin D in their body as a result of a problem with the parathyroid glands) do feel fatigued, even after a good night’s sleep.

Depression

Low levels of vitamin D have been associated with serotonin (the ‘feel-good hormone’) concentration in the brain and depression.  A study of Norwegian adults found that those with low levels of vitamin D were more likely to be depressed and that taking vitamin D supplements improved the symptoms.

Coughs and colds

Upper respiratory tract infections go hand in hand with the winter months, but research has shown how sufficient vitamin D may help reduce your chances of getting ill.  Studies have suggested that vitamin D is crucial to activating our immune defences, and that without sufficient intake of the vitamin our immune cells are unable to react appropriately.  One such study of school children showed that the incidence of flu was decreased when they were given a supplement.

What is the best source of vitamin D?

Vitamin D is often nicknamed as the ‘sunshine vitamin’ because its greatest source comes from the sun.  Your body is able to synthesis vitamin D under the skin when you’re outside in the sun, which is why it’s often referred to as a hormone as vitamins need to be obtained from the diet and cannot be made in the body.

Can you get enough vitamin D from food?

Very few foods contain vitamin D.  The main source is oily fish and a little can be found naturally in eggs and mushrooms.  You can also find vitamin D in fortified foods such as breakfast cereals and margarine spreads.

Vitamin D content of foods in mcg per serving

Vitamin D levels in food

What does a typical vitamin D rich day look like?

Breakfast:     2 eggs on toast with margarine spread (2.6mcg)

Lunch:           Mushroom stir fry (2.5mcg)

Supper:         Grilled trout with vegetables and potatoes (14.8mcg)

Is a vitamin D rich diet really possible?

In theory, it’s possible to get more than enough vitamin D from your diet but the reality is that your choice of food is very limited and whilst you may be able to eat eggs or fortified breakfast cereal every day for breakfast, the chances of you eating mushrooms and oily fish every day is less likely.  The recommendation for oily fish is also set at no more than 4 servings every week to avoid the build-up of heavy metals, which further limits your food choices.  Fish intake in the UK is also very low with only 23% of adults regularly eating oily fish varieties on a regular basis, lessening a dietary source of vitamin D.

At most, it’s likely that you may be able to get up to 20% of your vitamin D intake from food but the rest needs to come from sunlight in the summer and supplements during the winter.  Even if you’re lucky enough to escape the British winter with a sunny holiday, your stores of vitamin D are not likely to last more than 4-6 weeks.

Vitamin D Supplement Recommendations

Whatever your views on supplements, this is one vitamin that we can all clearly benefit from during the winter months.  Guidance is that all adults and children over the age of one consider taking a supplement (10mcg daily) during the autumn and winter months and that those in the ‘most at risk groups’, should consider taking a supplement all year round.  All babies under one year should be given a daily supplement of 8.5-10 micrograms unless they have more than 500ml of formula milk.
 
It’s very unlikely that you’ll get enough vitamin D from your diet, which makes supplements the most sensible option during the autumn and winter months to bridge the shortfall of intake and exposure to the sun.  Supplements are available in many forms such as sprays, tablets and gummies so choose something you are most likely to take on a daily basis.  When you’re deciding on a supplement then look for vitamin D3 as this is the form naturally found in the body and opt for a dose of at least 10mcg such as Healthspan Super Strength Vitamin D3* 60 tablets £3.95 and 240 tablets £9.95.  The best benchmark to taking a supplement is to start when the clocks go back in the winter and stop when they go forward in the spring.

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