Vitamin D

Vitamin D and your immunity

Helen Ross outlines the importance of getting your daily vitamin D and the role of supplementation.

This year, more than ever, we need to be aware of our vitamin D status.

A very recent retrospective cohort study published in the JAMA Network (2020), concluded that vitamin D deficiency may be associated with an increased risk of contracting the Covid-19 infection (1).

Unfortunately, we can easily get deficient in Vitamin D, especially during the winter months. So, besides helping to protect us against potential viruses, it’s important to know some of the reasons why getting enough of this fat soluble vitamin is so vitally essential to our overall health and wellbeing — and how we can make sure we are getting enough of it.

Why do we need it?

Here are six more reasons why you should ensure you are getting an adequate supply of vitamin D:

  • Vitamin D protects bone density, so therefore we need it to prevent osteoporosis.
  • Can help to reduce depression and enhance mood.
  • Alleviates musculoskeletal pain.
  • Improves our overall sense of wellbeing (2).
  • Vitamin D has also been implicated as an aid in the prevention of many serious conditions such as cardiovascular disease, rickets, depression, type 1 diabetes, cancer, epilepsy, polycystic ovary syndrome, and multiple sclerosis.
  • Balances Th-1 and Th-2 immune system responses, therefore plays a role in the prevention of autoimmune diseases such as Hashimoto’s thyroiditis, Graves disease, and rheumatoid arthritis (3).

Not all are aware of this vitamin, however. In fact, vitamin D is not actually a vitamin at all, it is a hormone (or a pro-hormone) and it plays a role in influencing hormone receptor gene interactions, which can then influence disease expression (2).

Interestingly, recent research is also showing evidence to support the hypothesis that vitamin D positively influences the composition of the gastrointestinal microbiota, although further studies are needed to fully understand the extent that vitamin D can modulate the gut microbiome (4).

There are three primary ways to get Vitamin D:

1. From the Sun

By far the best and most natural way to get our vitamin D (or Vitamin D3 – cholecalciferol) is from the sun. For this to occur, we need to expose as much of our skin as possible to the sun to get Ultraviolet B (or UVB). And it doesn’t take long. In fact, you can get adequate daily vitamin D3 from the sun in half the time it takes to get a tan, or to burn. Fifteen minutes of full body exposure (or as much as possible) should be plenty for most people. Your skin will produce more Vitamin D when it is exposed to the sun during the middle of the day.

When exposed to the sun, it is important not to allow your skin to burn. As there is contradictory research on the use of sunscreens for preventing various skin cancers, it is always a safer option to protect your skin (after your 15 minutes of exposure) by wearing suitable clothing or getting into the shade, to avoid getting too much sun exposure. Infants have very delicate skin and extra care should be taken to avoid sunburn.

Choose a natural sunscreen product if necessary. There are many on the market now without the harmful chemicals, which can be toxic to us and the marine environment (6). Always look for a natural and organic product that uses titanium oxide or zinc oxide, as opposed to oxybenzone or octinoxate as the main sunscreen agent. Reputable companies in the UK include Green People, JÂSÖN, UVBIO, EQ, Neils Yard, Lavera, and Yaoh.

2. Limited amounts from food

Obviously, in the UK we don’t always get the opportunity to get enough sun exposure, therefore we need to look at other ways of ensuring we get a good supply of vitamin D.

There are only a few foods that contain vitamin D — vitamin D-enriched mushrooms, and fortified foods, plus a number of animal products (oily fish, egg yolks, beef liver).

Unfortunately, these foods only have small amounts, which are not enough for our body’s needs. Therefore, supplementing with vitamin D is a recommended strategy especially for those living in colder climates.

3. From supplements

Unless you are getting at least 15 minutes of full-skin exposure to the sun on a daily basis, then supplementation is the way to go. Various government organisations recommend daily dosages of 600IU (International Units) per day for adults and children, and 400IU for infants. However, the Vitamin D Council recommends 5000IU per day adults, 1000IU/day per 25lbs of bodyweight for children, and 1000IU/day for infants, with even higher upper limits.

Bear in mind that vitamin D is a fat-soluble vitamin, and it can be difficult for the body to get rid of large amounts; however, for toxicity to occur, you would need to be taking around 40,000IU/day for at least two months. Some research has shown that some disease states, like multiple sclerosis and prostate cancer, may benefit from high doses (5).

Always ensure that your supplement is Vitamin D3, which is the same type that we get from the sun, and not vitamin D2. Please be aware that most D3 supplements are not vegetarian, but vegetarian and vegan supplements are also available.

Caution: If you are taking certain heart medications like digoxin, thiazide diuretics, or medication for high blood pressure, then please don’t take high doses of vitamin D. Other conditions that require caution include Hodgkin’s and non-Hodgkin’s lymphoma; hyperparathyroidism; kidney, liver or hormonal diseases. Always check with your GP to ensure you are taking a safe amount.


Meltzer, D. O. et al. (2020) ‘Association of Vitamin D Status and Other Clinical Characteristics With COVID-19 Test Results’, JAMA network open. doi: 10.1001/jamanetworkopen.2020.19722.

Institute for Functional Medicine, 2005. The Textbook of Functional Medicine,

Wentz PhD., I., 2013. Hashimoto’s Thyroiditis: Lifestyle Interventions for finding and treating the Root Cause,

Waterhouse, M. et al. (2019) ‘Vitamin D and the gut microbiome: a systematic review of in vivo studies’, European Journal of Nutrition. doi: 10.1007/s00394-018-1842-7.

Downs, C.A. et al., 2016. Toxicopathological Effects of the Sunscreen UV Filter, Oxybenzone (Benzophenone-3), on Coral Planulae and Cultured Primary Cells and Its Environmental Contamination in Hawaii and the U.S. Virgin Islands. Archives of Environmental Contamination and Toxicology, 70(2), pp.265–288.

Helen Ross

Helen Ross is a registered nutritionist and a gut health specialist.

Helen completed her BSc (Hons) in Nutritional Science in 2017 and has since worked as a nutritionist and a cook for retreat companies, as well as running her own business ‘The Well Life Lab’, helping her clients with personalised nutrition programmes, while also running cooking workshops, and one-day retreats. She specialises in gut health and IBS.