Vitamin D is getting a lot of press.  Once a supplement only considered in winter – self-isolation, and its links to help the fight against Covid-19 has seen a significant growth in its popularity.  Here, Aimée Benbow, BSc (Hons), MSc, ANutr at Viridian Nutrition answers the most commonly asked questions surrounding Vitamin D including, does SPF prevent its absorption, can to much of the supplement cause harm and what food sources are high in Vitamin D.

What is vitamin D?

Vitamin D is a nutrient that is supplied either through the diet or summer sun exposure.  What makes vitamin different from other vitamins is the fact it works within the body like a hormone.  Subsequently it is intricately involved in immunity, in fact vitamin D is necessary in every immune cell.  This may explain the association between lowered vitamin D status in those with chronic health conditions.  Additionally, research shows that supplemental vitamin D can improve mood in those who suffer with seasonal affective disorder, colloquially referred to as the winter blues.  Vitamin D has been shown to work with lactic acid producing beneficial bacteria (probiotics) to drive down inflammation and contribute to improved gastrointestinal health.  In fact, vitamin D receptors are found within all the human organs that include, the heart, kidney, bone and skin, which means that adequate vitamin D is necessary for those organs to function normally.

Although Public Health England recommends that all adults and children supplement with 400iu of Vitamin D from October through to March, a larger dose may be necessary for those with a diagnosed vitamin D deficiency.  

Does SPF prevent the body from absorbing vitamin D?

Sunscreens containing skin protection factors (SPF) work by blocking ultraviolet (UV) rays from the sun, particularly UVB the rays which causes sun burn. However, it is also UVB rays which when in contact with our skin, initiates the process that leads to our body manufacturing vitamin D. Therefore, we can see that the strict use of sunscreen can in fact lead to poor vitamin D status.

Why is it particularly important for the UK to take a vitamin D supplement now?

New guidance in 2016 from Public Health England (PHE), advises that throughout autumn and winter people should consider taking a daily supplement of vitamin D at 10micrograms (400IU). However, updated governmental advice released in April this year suggests that everyone should now consider taking vitamin D supplements throughout spring and summer particularly while in lockdown. With lockdown measures in place and many working from home, a significant number of the UK population remains indoors most of the day, even during the spring and summer months. Therefore, a large proportion of population may have experienced reduced exposure to the sun and hence have lower than normal circulating levels of vitamin D in the body.

What are the symptoms/indicators that you are experiencing vitamin D deficiency?

A variety of factors may affect vitamin D status, but symptoms of vitamin D inadequacy can be subtle, hard to identify, or even symptomless.  In fact, a recent trial showed 3 out of 5 adults in the UK during winter are deficient in vitamin D.  However, an increased frequency of infections, ongoing fatigue, unexplained back or lower body pain, poor wound healing and low mood can be general indications, subsequently these aspects may be more pronounced in the winter months when the sun is too low in the sky for vitamin D metabolism to occur in the skin.  Those at risk of lowered vitamin D status include those who follow a diet that is low in vitamin D, have limited skin exposure to summer sunlight, have dark skin, are obese or have issues with malabsorption, a digestive issue that reduces nutrient absorption.

If you are not deficient in vitamin D and add a supplement into your routine, can it cause harm?

Vitamin D is a fat-soluble vitamin which means it is stored by the body. As with other fat-soluble vitamins, if consumed in excess long term this can lead to toxicity. It is important, therefore, that if you have not been tested and do not know if you are deficient that you only supplement with 400IU of vitamin D as recommended by Public Health England. Supplementing with 400IU of vitamin D daily, even with adequate levels of vitamin D will not pose harm. Higher dose supplements are available on the market up to 2000IU which are advisable for those who have known vitamin D deficiency.

What sources are high in vitamin d?

The best and most efficient natural source of vitamin D is through controlled sun exposure, this can range from 20 minutes for those with fair skin to 40 minutes daily for those with darker skin.  Once vitamin D stores are fulfilled by sun exposure the mechanism halts and so levels will not achieve toxicity.  This gives the reasoning that even the best food sources of vitamin D are low and limited to oily fish such as salmon, mackerel and sardines besides dairy, eggs, and mushrooms, especially sun-exposed or ultraviolet light-exposed mushrooms.  Consequently, vitamin D is often fortified into foods, for example, to milk alternatives.

About Aimée Benbow, BSc (Hons), MSc, ANutr.

Aimee is passionate about nutritional product development and the impact and efficacy of nutraceutical ingredients. Working in the food and supplements industry for over 11 years, she has supported people’s health through product development, advice and education.

As Technical Services Director at Viridian Nutrition she is responsible for a team of Nutritionists, providing customer support and ensuring an understanding of the latest clinical research.  Aimee has launched over 20 products into the market based on consumer need and clinical efficacy. With experience managing a product range she has an in depth understanding of the industry regulations as well as the process to achieve certified organic status. A keen supporter of health food stores, Aimee is a regular speaker at training events to share knowledge and best practice.

A health and fitness advocate, Aimee has specialist knowledge of sports nutrition and has completed sprint triathlons and endurance events. Other focus areas include ageing, skin health and beauty. Additionally, with a passion for ethically and sustainably sourced ingredients, Aimee is also highly experienced in quality assurance and audit procedures.

Aimee graduated from the University of Surrey in 2008 with a BSc in Nutrition. In 2018 she completed a Masters degree in Nutritional Medicine and has also achieved a Diploma in Herbalism. This is supported by extensive experience in HACCP (food safety) and qualified supplier auditing.

Aimee believes that diet and lifestyle play a huge role in overall health and wellbeing, therefore it is vital to support people in achieving a healthy regime and optimum nutrition.