Health

The bright side of being in the sun

Do you find yourself seeking out the sun in winter or wondering why you feel so much better when the weather is good? It turns out there may be a scientific reason for this.

Words: Dr Marissa Kelaher

Vitamin D is a unique vitamin we mostly manufacture within ourselves in response to sunlight on our skin. We get very little of it from food.

It has many roles, including helping with calcium/phosphate metabolism, control of cell growth, immune function, insulin production, blood pressure regulation, bone and muscle strength, and improving mood. Severe vitamin D deficiency can cause muscle pain and bone weakness in adults, as well as rickets (soft bones) in children.

Low vitamin D levels have also been linked to a shorter life expectancy, as well as higher rates of autoimmune disease, allergies, diabetes, cancers, dementia, multiple sclerosis, heart disease, blood clots, strokes, and mental health issues.

In the past few decades public health advice has been to cover up in the sun, due to the increased risk of skin cancer with high levels of sun exposure, especially in New Zealand. There is now growing evidence that safe sun exposure may reduce the risk of ailments and diseases linked to low vitamin D.

An article in the Journal of Internal Medicine even concluded that avoiding sun could harm health as much as cigarette smoking. Yet trials supplementing vitamin D have had mixed results. A large-scale trial published in the prestigious New England Journal of Medicine (2019) showed that routine supplementation of vitamin D did not reduce the risk of cancers or heart disease risk at all.

In contrast, some other trials have shown that correcting vitamin D deficiency may improve allergies, immunity, risk of falls in the elderly, and bone and muscle strength, plus autoimmune diseases (especially MS), and dementia. As a result, scientists now believe that low vitamin D is just a marker for a lack of sun, and that the benefits of sunlight extend far beyond vitamin D levels. When skin is exposed to sun, it produces nitrous oxide - a molecule that dilates blood vessels, reduces blood pressure, induces a sense of euphoria and wellbeing, improves blood flow to tissues, and helps insulin sensitivity. Interestingly, nitrous oxide is also produced when you eat fruit and vegetables! Sun exposure also triggers the release of serotonin and endorphins (happy hormones), improving mood. But the advice always is taking it in small doses. In New Zealand our ultraviolet levels are high in summer, and so are our melanoma (skin cancer) rates, so caution is needed, and getting sunburnt is to be avoided, definitely. Sunbeds are not recommended as an alternative because of the higher UVs they emit – some are said to be more potent than the midday sun, while wearing sunscreen and covering up while outside is important. In Nelson we are lucky to have a lot of sunny days, as well as beautiful places in which to enjoy them. To reap the benefits of a safe dose of sunlight, head outside in the early morning or the late afternoon during summer. Any time of the day in winter is fine – it’s all about balance.

Dr Marissa Kelaher is a Nelson based GP who runs lifestyle, nutritional medicine and plant-based health clinics. She is based at Nelson Family Medicine. Check out Marissa’s blogs and health and wellness tips on Facebook and Instagram @thesimplicitydoctor