Vitamin D: Why It Might Be Top-Up Time!

Mother and child daughter show heart from hands at sunset on beach.


Vitamin D is truly our sunshine vitamin. When sunlight hits our bare skin our bodies’ start to make Vitamin D. Its our own human kind of photosynthesis, making an essential something just from pure sunlight. But what if we haven’t had a dose of sunshine in a while? Living in the more southern regions of the Antipodes, we are at a higher risk of Vitamin D deficiency. And Vitamin D is not something you want to be missing out on. 


When I was first studying nutrition in my naturopathic degree 15 years ago, Vitamin D was just a footnote. The main thing known about Vitamin D was that is was important for bone development, and that too little Vitamin D could cause softening of the bones and bowed legs in children, a condition called rickets. This was thought to be something historical, something we had moved beyond. 


Fast forward to 2019, and there aren’t many patients I don’t ask to get their Vitamin D levels tested. There is so much more we now know about Vitamin D and its critical function in many essential physiological processes. The other reason why its important to get tested is because Vitamin D deficiency is so very common. 


We now know that Vitamin D is almost like a hormone in its action, having influences on almost all body tissues, binding to receptors to influence gene expression in cells. Vitamin D receptors are found on the brain, the heart, the reproductive organs, the muscles, and our immune cells, showing the far-reaching effects of Vitamin D and the potential seriousness of the consequences of deficiency. 


Vitamin D is important for:


  • Immune health: Vitamin D supports our innate immune response, enhancing our response to both bacterial and viral pathogens. 


  • Cancer prevention: due to its role in regulating the immune system, Vitamin D has been shown to be a preventative factor in many cancers. 


  • Reducing inflammation: Vitamin D reduces inflammation of all kinds by calming down the production and release of some inflammatory mediators called cytokines. 


  • Reproductive health: Vitamin D is essential for the production of oestrogen and progesterone. Various studies confirm the importance of Vitamin D for various reproductive conditions, including PCOS. 


  • Pregnancy: Vitamin D is not only essential for baby’s skeletal development but also for various maternal health measures such as blood pressure and risks of pre-eclampsia and gestational diabetes. 


  • Male Fertility: Vitamin D is essential for sperm development, motility, morphology, and survival. It is also important for maintaining testosterone levels. 


  • Female Fertility: Amongst other factors, adequate levels of Vitamin D have been found to have a positive correlation with improved IVF outcomes. 


  • Healthy Mood: Although depression is a complex condition, many studies show a positive link between improved mood and higher Vitamin D levels. Vitamin D works on neurotransmitter release and may affect serotonin levels. As we also know it can decrease inflammation, and one model of depression points to neuro-inflammation as a contributing factor. Seasonal Affective Disorder or SAD is the official name for a serious kind of winter blues – again, Vitamin D levels that decline in winter may have a part to play. 


  • Those with auto-immune conditions: Vitamin D seems to affect a special immune cell called Th17, or T Helper cell 17, which plays a significant role in modulating immune function. Vitamin D may also directly reduce auto-antibodies. Studies have shown positive effects with Vitamin D supplementation on multiple sclerosis, psoriasis, type 1 diabetes mellitus and systemic lupus erythematosus (SLE). At the very least, Vitamin D deficiency has been linked to an increased risk for developing these conditions. 


  • Muscoloskeletal health and nutrient absorption: Last but not least, yes of course Vitamin D is still important for bone health and skeletal development. It is essential for the absorption of calcium, phosphorus and certain other nutrients. It also reduces the risk of fracture in the elderly, and not just because their bones are stronger but because with better Vitamin D levels they have less falls. This is because Vitamin D is also important for muscular function. 


But we often don’t get enough Vitamin D because….

  • We work and live indoors during daylight hours and don’t get enough sun
  • We cover up in the sun and use sunscreen because of the very real risk of skin cancers developing


And some people are more at risk than others of Vitamin D deficiency:

  • Those with darker skin have more melanin present and take longer to make Vitamin D, therefore often don’t get enough and risk deficiency.
  • Pregnant and breastfeeding women
  • People who are overweight or obese
  • Those living in a heavily polluted environment, as pollution limits the ability of UVB (Ultra Violet B) rays to reach your skin
  • Older people make less Vitamin D
  • Those with kidney or liver disorders
  • Those with digestive disorders such as Coeliac disease or Inflammatory Bowel Disease
  • Those living in more southern regions. Not only do we spend less time outdoors when its colder outside, but also at lower latitudes the angle of the sun’s essential UVB rays is too low to be utilised by our skin effectively. Long shadows in winter mean less ability to make Vitamin D. 


As you can see, winter is a vulnerable time for us in regards to Vitamin D. Not only do we not get as much sunlight, but the angle of the sun is lower. Added to this, winter is the time when we get a higher prevalence of infection, especially respiratory infections, and need additional immune support.


How to get your Vitamin D boost:


  • Safe sun exposure: Balancing sun exposure with sun safety is paramount, especially in New Zealand and Australia where our skin cancer rates are so high. The guidelines are that you can make enough Vitamin D in half the time it takes to get sun-burnt. This means about 15 minutes for many people on a typical summer’s day at peak time. For some with more vulnerable skin this is more like 10 minutes, while those with darker skin will be longer. Skin needs to be bare and uncovered for this time, without sunscreen. 


  • Eat Vitamin D-rich foods: Some foods are fortified with additional Vitamin D, but the highest natural sources include oily fish such as sardines, mackerel, salmon, cod and herring. Tuna may have Vitamin D but it also has mercury, so steer well clear of eating tuna. Cod Liver Oil has naturally occurring Vitamin D, as well as Vitamin A and essential fatty acids, making it a wonderful winter wellness supplement. Other non-fish sources include butter and eggs. Animal livers also have some Vitamin D. Foods are not enough to maintain good Vitamin D levels without sun exposure, but they are helpful. 


  • Supplements. Vitamin D supplements come in capsules, tablets, dissolvable lozenges and sprays. This means you can find a suitable supplement for every age and stage. If in doubt, there is no harm in most adults supplementing with 1000-2000iu of Vitamin D daily, especially through winter. Some people may need more however. Discuss a Vitamin D blood test with your GP. Knowing your specific levels will allow your practitioner to advise the right dose for you to move the Vitamin D into the optimal range. The optimal range is different from the ‘reference range’. While you may be in the ‘normal’ range this still may not be an ideal level for you, so do discuss options with your practitioner. Vitamin D3 (cholecalciferol) is the form of vitamin D you want in your supplement. 


If you have any recurrent infections, low immune function, auto-immune issues or inflammatory conditions, please do think about Vitamin D. Safe sun exposure will improve your winter wellness as long as you don’t get chilled! But don’t assume that your Vitamin D levels are fine. This is one test its always worth taking. 

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