HomeArticlesInside Our Food Vitamin D plays many roles in health, from bone development to strong immune systems. There is even emerging evidence that it protects against coronavirus. But if it’s so hard to find good dietary sources of Vitamin D, where does the Vitamin D in supplements come from? Vitamin D: Vital for Health It’s long been known that Vitamin D functions with calcium to keep bones healthy and avoid deformities such as rickets in children and osteomalacia in adults. But it is becoming increasingly clear that it also plays a vital role for our immune system, helping to fight off bacterial, viral and fungal invaders. Vitamin D appears to boost immunity in several ways, such as helping immune cells to function properly and dampening the inflammatory response.1,2,3 There is even some evidence that it protects against coronavirus since low Vitamin D levels have been associated with both a higher number of coronavirus deaths and cases for European countries and more severe outcomes for individuals affected by the disease.4,5 It may be no coincidence that the pandemic broke out in winter when people’s Vitamin D levels are typically at their lowest.6 ‘The Sunshine Vitamin’ Vitamin D has always been a curiosity among vitamins, being the only one our bodies can manufacture in the presence of sunlight. During the sunnier months, this is how most people obtain enough Vitamin D for their needs. But during winter, it can be very difficult to maintain good levels of Vitamin D through natural means alone. As a result, Vitamin D deficiency is widespread and thought to affect one billion children and adults across the globe.7 A prime reason is that there are few sources of this vital nutrient besides sunlight. Vitamin D2 vs D3At this point, it is important to point out that there are two main forms of Vitamin D: Vitamin D2 and D3. Both are essentially converted in the same way by our bodies into the active form. Vitamin D3 is the type we make in sunlight and is also found in a limited number of animal foods, such as oily fish and cod liver oil. Vitamin D2 comes from plants and fungi, including mushrooms grown under UV light. Vitamin D Supplements Since the number of food sources containing Vitamin D is so limited, many countries advise their citizens to take a daily Vitamin D supplement during winter. In some countries, foods such as milk, yoghurts and bread are also fortified with Vitamin D (of either form) to help ensure people have enough in their diet.But if Vitamin D is so difficult to get hold of, how are these Vitamin D supplements made? Surely they don’t come from mountains of cod livers or mushrooms?Vitamin D is made of sheep’s wool?Vitamin D supplements are made from either the D2 or D3 form – if you check the label, it should tell you which one has been used. They might look the same in pill form, but they come from very different sources. How Vitamin D3 supplements are madeFor Vitamin D3 supplements, the process actually starts with lanolin, a fatty substance secreted by the skin glands of sheep to condition their wool. It has been used variously by human cultures for thousands of years and today is an ingredient of many skin creams, beauty products and lip balms due to its waterproofing and barrier qualities. But it also provides the chemical precursors for making Vitamin D3. To produce Vitamin 3, sheep’s wool fleece is first washed to remove any impurities – which range from dirt and straw to faeces and parasites such as blow flies. A detergent is then added to extract the crude lanolin. This is then saponified: a process which converts the fatty component into chemicals that can be removed by centrifugation. The remaining lanolin alcohols are then refined further and subjected to a solvent wash and/or chromatography. This extracts crude cholesterol, which is the base ingredient for a series of chemical reactions that produce a compound named ‘7-dehydrocholesterol’, also called ‘pre-Vitamin D3’. This is illuminated by ultraviolet light to form Vitamin D3, mimicking the reaction that occurs in our skin. Vegan Vitamin DCertain people, such as vegans, may feel uneasy about using a product that comes from sheep. Furthermore, lanolin can also cause allergic reactions (and can be the basis for some apparent allergies to wool). In this case, Vitamin D2 supplements can be an option since these are made using a different process, through applying ultraviolet radiation to ‘ergosterol’, a compound obtained from yeast.But there’s a catch: recent studies indicate that Vitamin D3 supplements are significantly more effective than Vitamin D2 in raising Vitamin D levels in the body.8 Not surprisingly, entrepreneurs have spotted an opportunity to make a vegan version of Vitamin D3. The company Vegetology has produced what they claim to be ‘the world’s first vegan source of Vitamin D3’, extracted from lichens. These are symbiotic associations between two or more organisms: a fungus and algae and/or cyanobacteria. The lichens for Vegetology’s supplements are farmed in designated outdoor areas in Asia and North America. Vitamin D3 is extracted using methods similar to those in the pharmaceutical industry, using water and plant ethanol, and applying pressure.Getting Enough Vitamin DIf all this has made you think twice about where your vitamin supplements come from, the good news is that during the summer months at least you should be able to get enough Vitamin D simply by heading outside every day.