Sunshine – and vitamin D

April 19, 2021

Sunshine!  it has been lovely to see the sun this week, despite it still being quite chilly.  The sun and blue sky lift our mood and that is much needed at the moment and it also enables our bodies to produce vitamin D.

Whilst enjoying a few minutes in the garden I came across an article on some research looking at the benefits of vitamin D in reducing cancer mortality.  This is of particular interest to me as I’m currently doing a piece of work looking at nutrition to support people with cancer in their family who are concerned about their risk factors.

Vitamin D has been in the news recently for its beneficial role in reducing severity of COVID symptoms.  A few vitamin D facts as we enjoy the sunshine..

Why do I need vitamin D?

Vitamin D impacts health across our body, influencing how our genes express, promoting the absorption of calcium in the gut, regulating immune function, muscle structure and cell growth.  In the role of supporting immune function, it has been linked to reducing Covid severity and reducing cancer risk.  Low levels of vitamin D have been linked to muscle and bone weakness, Inflammatory Bowel Disease, high blood pressure, autoimmune conditions and diabetes.

Why might I not have enough?

Our weather!  Vitamin D is made from cholesterol via action of sunlight.  It takes a 15–30-minute exposure on arms or legs, between the hours of around 10am and 3pm in summer to produce around 10,000-20,000 IU.  I say in summer as this is dependent on the angle of the sun – an approximate idea is that your shadow needs to be shorter than your actual height.  Sunscreen use, air pollution, cloud cover, age and skin pigmentation can decrease effectiveness of production.   Unfortunately, older adults may produce up to 75% less.  People with darker skins will require more exposure time to generate the same amount of vitamin D.

There is vitamin D is available in a limited range of foods, mostly animal in origin.  This means it is important for vegans to check their status (as included in my Health Check).  The main food source is oily fish such as salmon and sardines.  It is also present in some mushrooms in the precursor to the active form of the vitamin (shitake for example).

The liver activates the vitamin D from both our food and our skin. It can be stored in the blood for a month or more.

Several genes enable the activation and transportation of vitamin D.  Changes in these genes which make this process less efficient are more prevalent in African Americans than Caucasians.  This can be tested for with a simple saliva test (see ‘Testing I use’).

Do I need to supplement?

Maybe – I like to work with improving our diets first, but as we can’t control the weather supplementation may be necessary, particularly during the winter. In the summer it is best to top up with sun exposure, not least because of the many other benefits to our mood and health.

It is best not to supplement any individual vitamin or mineral unless you know you are deficient.  This is because our body likes to keep everything in balance and loading with something can disturb the balance of the body in ways we don’t envisage.  Animal studies indicate that taking too much supplemental vitamin D can be toxic and may cause kidney stones, nausea, diarrhoea, and weight loss.  As vitamin D works in synergy with other vitamins your overall nutritional status is important.

I suggest testing your vitamin D level before supplementing as it is relatively easy – your GP can test, you can (cheaply) test at home using a finger prick test or I can run a test for you as part of working together.  You are aiming for levels 40-70 ng/mL.  If your result is lower than 35 ng/mL you may need to supplement.  Book a free discovery call if you wish to learn more.

What to look for in a supplement

Vitamin D3 is the active form of the vitamin.  As the body stores vitamin D, you can chose to take daily or weekly, the dose will depend on your current levels.  If you take a multivitamin daily, then do check if vitamin D is included before looking for an individual supplement.

Resources

City Assays are an NHS laboratory who offer home kits to test vitamin D levels at £29.  The directions are easy to follow.

http://www.vitamindtest.org.uk/

References

Vitamin D for All Over 50’s to Prevent Cancer Deaths? – Medscape – March 17, 2021.

Gropper, S.S., Smith, J.L. and Carr, T.P. (2018) Advanced Nutrition and Human Metabolism, 7th edn.

Malaguarnera, L. (2020) ‘Vitamin D and microbiota: two sides of the same coin in the immunomodulatory aspects’, International Immunopharmacology, doi: 10.1016/j.intimp.2019.106112

Lips, P. (2006) ‘Vitamin D physiology’, Progress in Biophysics and Molecular Biology, 92(1), pp.4-8.

Photo by Ibrahim Rifath on Unsplash

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