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how to boost your vitamin D

October 30 2017 by Jess

Our nutritionist Jess explains why we need vitamin D and the best ways of topping it up in winter months.

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Like all vitamins, vitamin D is essential to life, however what makes it stand out from the crowd is that we don’t only have to rely on food to increase our body’s levels. In fact, only about 5 to 10% of our vitamin D requirement comes from our food. So before we go into the best ways of topping up our vitamin D levels, let’s go into why we need vitamin D in the first place...

Jess, graze nutritionist
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Why do we need vitamin D?

Did you know vitamin D is actually considered a hormone?

Vitamin D keeps your bones healthy – it increases absorption of calcium and phosphorus and a deficiency results in impaired bone mineralization.

Vitamin D also affects your mood. Not enough may affect risk of depression; there’s a strong association with a lack of vitamin D and the onset of seasonal affective disorded (aka. SAD). During the sunlight-restricted months the rate of winter blues and depression sky rockets since a large part of vitamin D production is reliant on sunlight.

Vitamin D is also needed for a healthy immune system and to regulate gene expression playing a key role in cancer prevention. For a healthy mind, including reducing the chances of Alzheimer’s, vitamin D is a mineral that must be kept an eye on, as is the case for preventing type-2 diabetes and sex hormone imbalance since healthy ovulation requires vitamin D.

It is thought to play a role in blood pressure regulation. It's also important for healthy muscle function. A deficiency of vitamin D is also associated with an increased risk of some autoimmune diseases.

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How do we boost our vitamin D levels?

The most effective way to increase your vitamin D status is actually relatively easy – focus on safe sun exposure.

Obviously the ease with which can achieve this varies depending on your geographical location, your lifestyle, your job, the weather and/ or the season. Over the winter months we often find ourselves wrapped up warm or spending time indoors with less exposure to the sun, except for our hands and faces.

When the skin is exposed to sunlight, ultraviolet B (UVB) rays penetrate the skin and trigger a biochemical reaction that converts cholesterol in the skin to vitamin D, hence why vitamin D is often called the ’sunshine’ vitamin. So it is important to spend a little time each day exposed to the sun and to increase our food sources of vitamin D.

During the winter months, it takes a longer duration of sun exposure to the sun for our skin to actually synthesis enough vitamin D, so this again, affects our body’s vitamin D production power.

So if you don't spend much time outdoors in the middle of the day during the winter months, you may be at risk of vitamin D deficiency in spring.

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Vitamin D in your diet

Only oily fish is a significant source of vtamin D, while egg yolks, organic butter, meat and a few fortified foods provide small amounts. Vitamin D is found in the yolks of the egg, not the whites, so make sure you enjoy the whole egg, no egg white omelettes!

Other foods contain no vitamin D or negligible amounts and most of the population consume less than 3µg of vitamin D per day.

Fortified foods in the UK include:

  • Formula milks – infant formulas, follow-on formulas and growing up milks
  • Fortified milks – evaporated milk and fortified milks for toddlers e.g. Arla Big milk
  • A few breakfast cereals
  • Some brands of yogurts.
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vitamin D deficiency

While the majority of the population aren't clinically deficient, they don't have optimal levels of vitamin D to support all of its critical functions in the body.

This is the one vitamin which is really worth considering adding to your daily supplement regime given how essential it is to our long-term health and how sun-reliant it is to produce in our bodies. This ensures you have guaranteed levels each day.

As vitamin D is a fat-soluble vitamin, it's best to take supplements with a meal that contains some nourishing fats to maximize absorption.

If you supplement continuously, it's important to check your levels periodically as you can have too much vitamin D.

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If you are concerned about your vitamin D levels, see your doctor to have your levels tested. If your vitamin D levels are low, a supplement may be necessary.

Jess, graze nutritionist


  1. Scientific Advisory Committee on Nutrition (2015)
  2. Public Health England and Food Standards Agency (2014)
  3. Clemens TL, Henderson SL, Adams JS, Holick MF. Lancet 1982: 1(8263): 74-76
  4. Holick MF. J Investig Med. 2011;59(6):872-80
  5. Dror DK. Curr Opin Obstet Gynecol. 2011 Dec;23(6):422-6.
  6. Bodnar LM, Catov JM, Hyagriv NS, et al. J Clin Endocrinol Metab 2007;92:3517e22.
  7. Cancer Research UK (2010)
  8. National Institute for Health and Care Excellence (2016) Nice Guidance 34 Sunlight Exposure: Benefits and Risks
  9. Department of Health (2012) Letter from Chief Medical
  10. Officer to Healthcare Professionals: Vitamin D: Advice for at risk groups
  11. Department of Health (1998) The Stationery Office, London.
  12. National Institute for Health and Care Excellence (2014)
  13. National Institute for Health and Care Excellence (2015)
  14. EFSA (2012) EFSA Journal 2012;10(7):2813 [45 pp.]. doi:10.2903/j.efsa.2012.2813
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By Jess, graze nutritionist.

Our nutritionist extraordinaire, Jess trained at the Institute for Optimum Nutrition and is a registered practitioner with the British Association for Applied Nutrition & Nutritional Therapy. She's the creator of our health badges, to help you choose the snacks and boxes that are right for you. Check out everything from Jess on our blog, with recipes and tricks to help you keep making better choices, or go to Jess's blog at for even more.

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