Getting the “D” you need?
Image credit: Unslaph - Yogesh Pedamkar
During the months of autumn the sun is lower, the days are shorter and the skies are often grey. But, are you aware this could be impacting your nutritional status?
We obtain our vitamin D not only from the food we eat but also from sun exposure. Our bodies actually make vitamin D when the skin is exposed to UVB rays and this is why it is sometimes referred to as the “sunshine vitamin”. In fact this is the main source of vitamin D for most people and therefore it probably no surprise that an estimated 25% of the UK population are likely deficient and many more of us are likely to have sub-optimal levels [1, 2].
Why is this the case? Food sources are limited and farming methods over the years have depleted many natural food sources of their vitamin D content and fortified foods are limited, coupled with the westernised diet our intake of vitamin D from food sources makes up only around 10% [3, 4]. In the northern hemisphere the reduced sunlight and indoor lifestyles impact our production and therefore, our stores often get depleted quickly over the darker colder months [5]. The difficulty in obtaining sufficient intake from food and this decreased exposure to UVB light during the autumn and winter months along with the prevalence of deficiencies actually led to Public Health England’s (PHE) recommendation that all UK residents should supplement autumn through winter [6, 7]. The reference nutrient intake of vitamin D for an adult is 10μg in the UK, however it is questioned by many whether this intake is sufficient for optimal health benefits [8]. There are also many other factors that can contribute to low vitamin D levels, including pregnancy and breastfeeding , obesity, age, skin colour, low magnesium and even genetic variants [9-15]. So with the increased time most of us are spending indoors in 2020, it is vital we think about ways to increase our intake when our ability to make enough is hindered.
Why do we need vitamin D?
Vitamin D is an important vitamin involved in many functions in the body and behaves like a hormone by helping to regulate the function of many body systems but some of the main roles of vitamin D are in:
Supporting bone, muscle and connective tissue health, particularly bone density due to it enhancing the absorption of calcium and phosphorus [16].
Supporting the immune system, therefore reduced vitamin D status can negatively impact our immune health which is important over these colder months when flu season in the UK begins [17-19].
Stimulates production of serotonin, often referred to as the “happy” hormone and as such low levels of vitamin D can have an impact on mood. This is extremely relevant to the estimated 3-29% of the UK population who suffer from Seasonal Effective Disorder (SAD) as studies suggest this is the time of year it is at its peak and reduced serotonin levels may be one of the causes [20-22].
It is therefore not surprising that suboptimal vitamin D levels have additionally been linked to an increased risk of immune and musculoskeletal dysfunction and various other common conditions including diabetes and depression [23-26]. Vitamin D has even hit the media headlines a lot over the last few months with studies suggesting that low vitamin D status is linked to an increase in COVID-19 severity and the long-term impact of infection, this is nothing new as vitamin D has previously been associated with reduced risk of respiratory infections [27-29]. So there has never been a better time to start considering our intake and working towards optimising our vitamin D status [6, 20].
Can you increase your intake of vitamin D naturally?
Increasing your vitamin D through your food intake can be hard if you are already consuming a balanced diet, although it is not impossible by eating mindfully. Here are a few foods you may want to incorporate into your diet if you wish to improve your intake naturally:
Oily fish (recommendation is 2 portions/week)
Eggs
Dairy
Mushrooms
Tofu
Fortified products (food products that have had vitamin D added to them)
Do you require a supplement and if so how much should you be taking?
It really depends on the person but PHE recommends adults supplement with with 10μg of vitamin D daily autumn through winter, as it is difficult to obtain sufficient amounts from food sources. However, when taking any supplement even those recommended by PHE it is advised you run this by your GP or nutrition professional especially, if you suffer from a medical condition or are taking any medication.
Some people who suffer from specific conditions Arthritis, Multiple Sclerosis (MS), Myalgic Encephalomyelitis/Chronic Fatigue Syndrome ME/CFS, Osteoporosis, SAD, depression or who are obese for example, may benefit from higher doses and/or supplementation throughout the year, however, this should only be considered if under the supervision of health professional or nutrition professional [11, 19]. Why? Low vitamin D status even if it has been checked through testing can be due to other factors other than intake or production [14,15]. High doses can additionally effect the absorption and utilisation of other nutrients and often with higher doses and/or specific conditions other vitamins would be recommended in line with an increased vitamin D intake [14, 31, 32].
Even if supplementing you should still consider increasing your intake of food sources and getting some autumn sunshine as research suggests a combination of sources may be the best way to achieve optimal vitamin D levels [8].
Stay happy and healthy,
C h e l
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