While many of us still bask in the glow left by summer, unfortunately daylight saving has recently come to an end, signalling the slide towards winter, with shorter days, cooler temperatures and warmer clothes. We start to cover up reducing both skin and sun exposure, making it harder for the body to produce the vitamin D it needs to keep us healthy. This is a worry since around 50% of New Zealanders have less than optimal levels of this versatile vitamin to start with.1,2
Our ability to produce vitamin D in the skin is determined by a number of factors, such as time of day and time of year, age, skin type and colour and length of sun exposure.
The sun in New Zealand winter is at a different angle making less UVB light available to produce vitamin D in exposed skin.
So if you live in the bottom of the North Island and anywhere in the South Island you could go outside in your “birthday suit” for as long as you like and get nothing but a chill between the months of April to October.3So eating food high in Vitamin D or supplementing may been necessary over the winter months.
People with SAD or the “winter blues”can feel sad, irritable, and may cry easily; they feel tired and lethargic, have difficulty concentrating, sleep longer than normal, lack energy, are less active, withdraw from social situations, crave carbohydrates and sugars, and tend to gain weight due to overeating.4
Women tend to suffer more than men and onset is between 18 and 30 years of age.
The further you live from the Equator the more susceptible you are.4SAD is thought to be linked to low levels of vitamin D, increased melatonin levels and reduced serotonin activity. Combined these factors result in low mood, poor mood regulation and in severe cases depression. 4
An inborn internalreward system for sun exposure indicates that UV exposure is important for health.5 Interestingly research has shown that sun exposure can lead to addictive behaviour, by activating the production of beta-endorphin in special skin cells called keratinocytes.6,7
Beta-endorphins are a “feel good” chemicals that increase dopamine to support good mood. They possess morphine like effects and are involved in the body’s natural reward circuits to enhance pleasure and reduce pain.8
In some countries light boxes are used to simulate natural daylight to help support vitamin D levels and mood balance.4
Winter is known as the cold and flu season and we spend more time indoors making it easier for viruses to spread and take hold. Vitamin D has been shown to play a role in regulating the immune system, and vitamin D deficiency is associated with poor immune function.
Research shows that vitamin D induces the production of special antimicrobial substances in the body called cathelicidins and defensins.4 When vitamin D levels drop over winter it makes it harder for the immune system to protect the body from viruses and infections.
Vitamin D supplementation in the elderly and people with primary immune deficiency has been shown to reduce antibiotic consumption by 50 – 60% compared to placebo.
Many foods in New Zealand are routinely fortified with B-group vitamins. Unfortunately very few foods are fortified with vitamin D so consider topping up your vitamin D levels now, rather than leaving it until later to support your health and your family’s health over the winter season.
For those of you who are interested in finding out more about the versatile vitamin have a look at The Vitamin D Council website and maybe sign up for the informative regular newsletters.
Debora-Dale Young Clinicians Pharmacist
References are available on request.
1. Lips P. Worldwide status of vitamin D nutrition.J Steroid Biochem Mol Biol.2010;121(1-2):297-300.
2. Rockell JE, Green TJ, Skeaff CM, et al. Season and ethnicity are determinants of serum 25-hydroxyvitamin D concentrations in New Zealand children aged 5-14 y. J Nutr. 2005;135(11):2602-2608.
3. The Vitamin D Council Website. http://www.vitamindcouncil.org/about-vitamin-d/how-do-i-get-the-vitamin-d-my-body-needs/ Accessed 4.4.2016.
4. Melrose S. Seasonal Affective Disorder: An Overview of Assessment and Treatment Approaches. Depress Res Treat. 2015;2015:178564. doi: 10.1155/2015/178564. Epub 2015 Nov 25. PMID: 26688752. [Full text free].
5. Lindqvist PG, Epstein E, Nielsen K, Landin-Olsson M, Ingvar C, Olsson H. Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort. J Intern Med. 2016 Mar 16. doi: 10.1111/joim.12496. [Epub ahead of print] PMID: 26992108.
6. Fell GL, Robinson KC, Mao J2, Woolf CJ, Fisher DE. Skin β-endorphin mediates addiction to UV light. Cell. 2014 Jun 19;157(7):1527-34. doi: 10.1016/j.cell.2014.04.032. PMID: 24949966. [Full text free].
7. Tejeda HA, Bonci A. Shedding "UV" light on endogenous opioid dependence. Cell. 2014 Jun 19;157(7):1500-1. doi: 10.1016/j.cell.2014.06.009. PMID: 24949960. [Full text free].
8. Sprouse-Blum AS, Smith G, Sugai D, Parsa FD. Understanding endorphins and their importance in pain management. Hawaii Med J. 2010 Mar;69(3):70-1. PMID: 20397507. [Full text free].