The cold temperatures and dark days of bleak mid-winter are upon us and many will be feeling the pinch on their mood. Seasonal Affective Disorder (SAD) or ‘winter blues’ are common at this time and those who struggle with mental health issues such as depression and anxiety may be feeling particularly bad. But why does this phenomenon of low mood happen? And is there anything we can do about it?

Vitamin D is Unique

The answer lies with a special vitamin known as Vitamin D3 or cholecalciferol. Discovered during research into rickets in 1922, the term ‘vitamin D’ refers to a group of fat-soluble steroid molecules. These molecules are currently understood as the pro-hormones responsible for healthy mineral metabolism and bone growth – that is, they are the ‘prerequisites’ or raw materials that enable these functions in the body.

Vitamin D is nicknamed the ‘sunshine vitamin’ because the body naturally produces a sufficient quantity of it in the skin upon exposure to sunlight. In this way it is unique within the vitamin family – humans obtain all other vitamins for health through diet, whereas we are naturally able to synthesise our own source of vitamin D from the sun. In this respect, Vitamin D is more like a hormone than a standard vitamin. It is also a fat-soluble vitamin, which means reserves can be stored in the body.

Vitamin D Manages Minerals

Much of what we know about vitamin D has been learned over just the past 15 years and there remains a significant volume of research underway to determine the full role it plays within the overall health of the human body. However, two known major functions of vitamin D implicate why its application is so anatomically diverse and critical to overall wellness:

The most dramatic known effect of vitamin D is to facilitate intestinal absorption of calcium and enhance absorption of other key minerals vital for health such as magnesium, iron, phosphate and zinc. Vitamin D stimulates the expression of a number of proteins involved in transporting essential minerals from the gut into the bloodstream for distribution. Each mineral is article-worthy of itself as collectively our essential minerals enable the functioning of all our major systems. Vitamin D is most widely recognised for its role calcium absorption as it was this function that led to its discovery. It is responsible for bone structure and strength.

In enabling the absorption of essential minerals, vitamin D serves an implicit supporting role in assisting healthy core processes, the breadth of which spans from hormonal wellness to cardiovascular function, respiratory support, brain development and mental performance. Sunshine is life!

Vitamin D Makes Healthy Cells

Activated vitamin D functions as a steroid hormone, fulfilling the role of either key or gatekeeper for more than 2,700 different cell receptor sites across the human genome. Vitamin D helps to prevent the overall propagation of disease by regulating expression of healthy genes and non-expression of harmful ones.

In performing this vital function for healthy gene expression, vitamin D has been linked to the prevention of over 100 different diseases. A recent review by the Vitamin D Council associated optimal blood levels of the vitamin with a dramatic spectrum of health benefits, including 77% reduction in all cancer incidences and 64-90% reduction in infections.

A Special Kind of Sunshine

Vitamin D production specifically requires UVB sunlight, which sits on the UV spectrum next to UVA. Unfortunately this requirement for UVB creates several challenges to maintaining robust levels of vitamin D year round:
• The tilt of the Earth’s axis means that much of the Northern Hemisphere is not exposed to UVB rays for significant portions of the year. In the UK, this period runs from October to March throughout autumn and winter
• In these northern regions, overcast weather in spring and summer often prevents UVB light from reaching the ground
• Sunscreen absorbs ultraviolet light and prevents it from reaching the skin – SPF 15 will reduce vitamin D synthesis by 98%
• Exposure to sunlight through windows does not stimulate vitamin D production because glass almost entirely blocks UVB light
• Significant levels of naturally-occurring vitamin D in food is scarce

The Perfect Winter Storm

The sum of the above means that the average person living in the West has limited exposure to the sun owing to an increasing number of hours spent indoors owing to work demands and digital pastimes. In addition, geographical factors mean that there are large portions of the year when UVB rays simply do not reach the regions where they live.

When sunshine eventually arrives, sunscreen is often applied as a preventative measure against harmful UVA rays but also stops UVB reaching the skin. With the arrival of October the body begins to utilise its stored vitamin D, which holds 3 months supply at full capacity i.e. if it’s been a good summer.

By the time January arrives the 3 month reserves are empty. Mineral uptake is impaired in the gut, starving the body of much needed raw materials for healthy major functions. Hormone and enzyme production is compromised causing mood-related symptoms and a weakening of energy. Fear creeps in, exacerbating anxiety and depression. Welcome Winter blues!

Beating the Winter Blues

The optimum way to boost vitamin D levels is exposure to natural sunlight without sunscreen for 15-20mins a day. For those enough lucky enough to live in a warm climate, spending this short amount of time outside in the daylight will help keep your mood boosted and body well throughout the year. For those of us less fortunate, here are some recommendations to keep deficiency at bay:

1. Use an organic, ethically sourced supplement throughout autumn and winter ( the UK Government has already recommended this course of action) There is divided opinion about the correct dosage of vitamin D and in rare cases over-supplementation can cause toxicity. Given that a fair-skinned person sunbathing for 20mins will produce approximately 10,000iu I usually recommend a dose of 2500-5000iu daily
2. Supplement in line with the body’s normal circadian rhythm to mimic natural hours of sunlight i.e. take your vitamin D in the morning or at noon. Ingestion in the evening may cause wakefulness or compromise sleep integrity as the influx of vitamin D tricks the body into thinking it is daytime

3. For optimum absorption and benefit, support the new influx of vitamin D molecules by also supplementing good levels of the vitamins and minerals it usually interacts with; calcium, magnesium and vitamin K – a good multi formulation is ideal

4. If you particularly miss the warmth and brightness of the sun during winter consider investing in a SAD lamp, which mimics UVB rays to stimulate vitamin D production. It is of course a substitute for the real thing but can be a great comfort during the cold dark days

5. Our ability to produce vitamin D reduces with age as the integrity of the skin degrades. If you are over 50 years old it would be beneficial to maintain supplementation year round. The same applies to those suffering with skeletal diseases, metabolic disorders, cancer, cardiovascular disease, autoimmune disorders, cognative/mental health issues or infection

6. Don’t fall into the January detox trap! Try to practice radical self-care during these harsh months and if you happen to have some air miles and holiday leave left this is a great time to cash in for some vitamin D-boosting time on the beach


Isabel Ocaña PDNN is a qualified Naturopathic Nutritionist  and member of the Naturopathic Nutrition Association. Her journey into wellness began when she sought alternative healing approaches to battle her own disordered eating and anxiety. Learning simple, natural ways to heal inspired Isabel to retrain as a nutritionist, share her education and empower others to live healthy, symptom-free lives. 
Isabel’s mission is to educate, motivate and inspire health transformation through natural, effective positive eating. A British national, she currently lives in Oakland, California with her husband where she offers personalised nutrition counselling to a variety of clients.
For more information or to book a session with Isabel contact us