Not sure about you but I really find January the hardest month of the year! I get hit quite badly with SAD and resort to my SAD lamp and increasing my vitamin D/K2 capsules, which become my companions until the spring has sprung (usually May time), when I can finally benefit from the daylight and blue skies and sunshine! Many people focus on dietary changes during this time and choose to join in with “Veganuary”, opting for a vegan diet during the month of January, check out my article. Increasing plant-based foods is a good way to support health, however certain nutrients can be hard to obtain from a vegan and plant based diet, including vitamin D.

In addition, the body’s own vitamin D production relies on exposure to sunlight which is lacking at this time of year. They grey skies not only affect our mood and make you feel miserable but deplete us of our Vitamin D, therefore it really is a good time to consider taking a quality vitamin D supplement. I don’t usually advocate taking lots of vitamins and minerals as I believe if we eat the right foods and good quality foods we are able to obtain them quite easily, however, and this is important for peri and post menopausal women, we DO need to think about supplementing with vitamin D, Omega 3, vitamin B’s and a good probiotic.

So who is at risk of low levels of vitamin D?

Usually during the summer months we get sufficient sunlight to convert into vitamin D, but that’s not always the case. Those populations at most at risk are the aging, so if you have elderly male or female relatives who are unable to get out and about (either at home, care home or hospital) it is important that they too, supplement with vitamin D. As we age, so does our skin and it becomes less able to manufacture vitamin D, therefore supplementation for everyone as we age becomes vital.

Other studies have shown that the prevalence of vitamin D insufficiency in vegans was higher than in omnivores (73% versus 46%), therefore vitamin D status should be considered in those following a vegan diet5.

Other populations who are at risk include:
• People with dark skin, as the ability to absorb UV light is reduced with darker skin
• Obese people, it has been shown that obesity can increase vitamin D deficiency
• People who have reduced exposure to UV light i.e. those who work indoors all of the time, children who do not play outside and people who cover-up or use high factor sunscreen etc.
• Children under 5 years of age

Where do we get vitamin D from?

When the skin is exposed to the UVB radiation from sunlight a molecule is derived from cholesterol and converted into vitamin D, known as D3. It can also be derived from your diet or by taking supplements, which are usually animal derived. Some great natural sources of vitamin D are oily fish, eggs and butter but vegan sources can be obtained from lichens, mushrooms, fortified soya milk and almond milk or by vegan supplements, which should be clearly labelled.
Vitamin D functions and Seasonal Affective Disorder

Vitamin D is the most highly researched nutrient – with a search on “vitamin D” returning over 80,000 hits on PubMed. Although research is often small and inconclusive, it is widely believed that vitamin D deficiency plays a significant role in the onset of many conditions.

What about SAD?

Seasonal affective disorder or SAD is a type of recurring major depression with a seasonal pattern. According to the Diagnostic and Statistical Manual of Mental Disorders, the criteria for SAD includes having depression that begins and ends during a specific season every year (with full remittance during other seasons), for at least two years and having more seasons of depression than seasons without depression a long period of time. Seasonal pattern disorders occur most frequently in winter although they can also occur in summer.

A systematic review and meta-analysis concluded that low levels of vitamin D are associated with depression. Many people with SAD have insufficient or deficient levels of vitamin D and research investigating this association suggests that supplementing vitamin D may improve their symptoms.

SACN recommends all members of the population should obtain:
• “a reference nutrient intake (RNI) of 10 micrograms of vitamin D per day, throughout the year, for everyone in the general population aged 4 years and older
• an RNI of 10 micrograms of vitamin D per day for pregnant and lactating women and population groups at increased risk of vitamin D deficiency
• a ‘safe intake’ of 8.5 to 10 micrograms per day for all infants from birth to 1 year of age
• a ‘safe intake’ of 10 micrograms per day for children aged 1 to 4 years”
However, those at risk of vitamin D deficiency/insufficiency or who know they are vitamin D deficient may need to increase their intake further.

Maintenance – in order to support general wellness over the winter months, generally I would recommend a good quality multivitamin and mineral, which includes 30ug vitamin D3. However the amount of vitamin D required for different people will be specific to them. This needs to be ascertained from a blood test, so if you are feeling generally under the weather go to your GP and ask for a blood test. There is a good calculator on the https://www.grassrootshealth.net/project/dcalculator that will give a and indication of how much (i.e. dose) and how long to supplement with vitamin D based on your blood test results. I am just waiting for mine to come back, at the time of writing this.

Vitamin D deficiency

If your tests come back and have demonstrated vitamin D levels are deficient, a higher dose of vitamin D should be considered (e.g 4000IU) especially over the winter months to help restore adequate vitamin D levels. High dose vitamin D3 should be taken alongside vitamin K2, to support calcium homeostasis (by directing calcium into bone away from arteries – this is absolutely ESSENTIAL). D3 levels should be tested after 3-6 months, reducing dose once optimal levels are achieved.

Other ways to support vitamin D levels

Food sources:
D3: oily fish, eggs, butter
D2: Mushrooms, soya and almond milk

Sun exposure
A great way to obtain vitamin D is via exposure to UVB light. This is difficult through the winter months (particularly October to May) however during the summer months it is a good idea to get appropriate levels of sun exposure. To obtain vitamin D from the sun you need to expose your face, legs and forearms to sunlight (between 10am and 2pm) for ten minutes without sun protection on as many days as possible through the summer. Ensuring, though, that the skin does not burn or redden.

Key Takeaways
• Vitamin D deficiency is most common in winter, affecting 30-40% of the population, with institutionalised adults being the greatest affected. In addition, many more people have sub-optimal levels of vitamin D. Many more people may have sub-optimal levels of vitamin D.
• Those at particular risk of vitamin D deficiency include people consuming a vegan diet, people with dark skin, older adults, people who rarely expose their skin outdoors and obese individuals. Children under 5 are also at a higher risk.
• Vegan sources of vitamin D are in the vitamin D2 form, which needs to be converted by the body to vitamin D3. Therefore, it can be difficult for vegans to obtain adequate levels of vitamin D especially during the winter.
• Vitamin D deficiency is associated with seasonal affective disorder and vitamin D supplementation has been shown to be helpful for these individuals who experience this during the winter months.
• Vitamin D deficiency also plays a significant role in the onset of many other conditions.

Vitamin D contributes to:
• The absorption and utilisation of calcium and phosphorus
• Normal blood calcium levels
• The maintenance of bones and teeth
• The maintenance of normal muscle function
• The normal function of the immune system
• Vitamin D has a role in the process of cell division
• Vitamin D is needed for normal growth and development of bone in children
• Vitamin D helps to reduce the risk of falling associated with postural instability and muscle weakness. This is a real consideration post menopause as falling is a risk factor for bone fractures among women 60 years of age and older. (also men are at risk)

References
1. Vitamin D and Health 2016 Ii.; 2016. https://www.gov.uk/government/groups/scientific-advisory-committee-on-nutrition. Accessed December 3, 2019.
2. New advice on vitamin D – British Nutrition Foundation. https://www.nutrition.org.uk/nutritioninthenews/new-reports/983-newvitamind.html?__cf_chl_jschl_tk__=2fa3d847d00598101ecd8713a2e127506cdfb39b-1575369996-0-AYCshmmhlGi3_-BBNCDADdGOVTtJtO5YKYx2-W8mSoWeDzMVNU43q6jpgFO3X5TFNoQ1UHi2Tk-eV5f8Hv2LxTYLS5DQP-8B964A7sjPfSO7IJxJzfwruqkChQSucQOrzXUWC3b0cK73Lkh1AJ_3fUBTtVsxzsEknWJ8MabXg6P2Ysxw5TAfvW4FfjNZ9cen1rtoqtS6pLYFuyQfTJfQBh-K2iMKMunAZqj528LKBe3E4msQ6GSZFHPzrmtsL9NqVOUFMYR2sDVf3wZI8ZvbtZkJ4u2AGDzomjHVitXz9hbWi2433_9r8NO6bcx9B2OwLn2XnGsyNT21TBli1dmR9aScIWopzsVOAZU1X1mp_xsIf3XaqyBpiqUZuaYXIW9mqbkq6bwG04_vJEiDmjKoCgI. Accessed December 3, 2019.
3. Scientific Opinion on the Tolerable Upper Intake Level of vitamin D. EFSA J. 2012;10(7). doi:10.2903/j.efsa.2012.2813
4. www.grassroots.net
5. Ho-Pham LT, Vu BQ, Lai TQ, Nguyen ND, Nguyen T V. Vegetarianism, bone loss, fracture and vitamin D: A longitudinal study in Asian vegans and non-vegans. Eur J Clin Nutr. 2012;66(1):75-82. doi:10.1038/ejcn.2011.131
6. Murray JPM. Textbook of Natural Medicine. 4th Ed.; 2013.
7. Bland J et al. Textbook of Functional Medicine.; 2008.
8. Swanson CM, Nielson CM, Shrestha S, et al. Higher 25(OH)D2 is associated with lower 25(OH)D3 and 1,25(OH)2D3. J Clin Endocrinol Metab. 2014;99(8):2736-2744. doi:10.1210/jc.2014-1069
9. Oliveri B, Mastaglia SR, Brito GM, et al. Vitamin D3 seems more appropriate than D2 to sustain adequate levels of 25OHD: A pharmacokinetic approach. Eur J Clin Nutr. 2015;69(6):697-702. doi:10.1038/ejcn.2015.16
10. Melrose S. Seasonal Affective Disorder: An Overview of Assessment and Treatment Approaches. Depress Res Treat. 2015;2015. doi:10.1155/2015/178564
11. Oseiki H. The Nutrient Bible. 8th Ed. Bio Concepts Publishing Australia.; 2009.
12. Piotrowska A, Wierzbicka J, Żmijewski MA. Vitamin D in the skin physiology and pathology. doi:10.18388/abp.2015_1104
13. Thank you to Cytoplan for their article