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Vitamin D is often touted as being an important supplement to take. It’s needed to regulate absorption of calcium and phosphorous in the body, which helps to maintain bone strength and protect against osteoporosis and rickets. Researchers have also found links between low levels of vitamin D and increased risk of several health conditions, including falls, cardiovascular disease, diabetes, depressed moods, and cognitive deterioration.
There are 2 types: vitamin D3 and vitamin D2. D3 is found in animal-sourced foods and D2 found in fortified and plant-based foods. D3 is considered to be superior. Keri Briggs, Technical Advice Manager from Lamberts Healthcare explains that “D3 is widely considered the superior option and raises vitamin D levels more quickly and for longer than D2”.
It acts like a hormone
The way vitamin D is described can be misleading, says Keri. “Vitamin D is often called a fat-soluble vitamin, but in reality it acts more like a hormone in the body; it can be made by the body after exposure to sunlight which vitamins can’t, and it helps to regulate the production of other hormones important for bone health and the concentration of calcium in the blood”.
Can we get enough from our diet or lifestyles?
Yes, it’s possible. However, there are obstacles to obtaining an adequate quantity: oily fish is a rich source of vitamin D but is often avoided by people in the UK. “Other dietary sources include dairy produce, fortified cereals and margarines, and offal, but these sources contain quite small amounts of this nutrient; for example an individual would need to consume 450g of Bran Flakes or 10 eggs to reach the 10 micrograms (400iu) level that is suggested for most people” explains Keri.
Other factors including high SPF and less time spent outdoors prevent many making sufficient quantities of vitamin D. Moreover, “between late September and April, the angle of the sun means that those living in as the UK will make little or no vitamin D in their skin. People with darker skins, the elderly and those who cover much of their skin in the summer may also struggle to make a sufficient quantity”, explains Keri. Public Health England also advise every adult to take a 10-microgram supplement in autumn and winter, and that those at risk of lower vitamin D levels, including people with darker skin, take a supplement year-round. Children between the ages of 1 and 4 years should take 10 micrograms of vitamin D too, according to The British Nutrition Foundation.
In current circumstances, the Association of UK Dieticians has advised those who are unable to go outdoors to consider taking 10 micrograms of vitamin D each day.
Great, I’ll buy some!
Not so fast. Vitamin D supplementation is a contentious topic, and it’s worth exploring this a little more.
Argument against:
We know reasons for taking it, but there is a strong argument that vitamin D supplementation is not a good idea. Professor Tim Spector from Kings College London explained in 2018 that guidelines were shaped by 1980s trials conducted into supplementation in care homes and are "probably flawed".
Professor Spector also explained that he sees an increasing number of patients with very high levels of vitamin D, and that “several randomised trials have shown that patients with high blood levels or taking large doses of vitamin D (above 800IU) had an unexpected increased risk of falls and fractures”. Similarly, he argues that “it was widely believed that vitamin D supplements prevented cardiovascular disease, but meta-analyses and large-scale genetic MR studies have ruled this out”.
Argument to take even more:
To confuse matters further, some believe that not only should we take it, but that we need to take more. In 2018, researchers at the University of Birmingham found that the “UK has the lowest adherence to infant vitamin D supplementation in Europe”. Paediatric A&E doctors here in the UK were found to “frequently encounter dark-skinned infants with hypocalcaemic seizures, and rickets during winter and spring” by these researchers: Dr Högler and Dr Uday.
So what do I do?
It’s clear that this is a divisive topic, and that medical professionals do not unanimously agree whether we should all supplement with vitamin D in the UK, let alone how much to advise the UK population to take.
One thing is certain, however. Whether to take vitamin D depends on a whole host of factors about you as an individual, including the pigment of your skin and how quickly your body makes new bone. Ideally, you would go to a medical professional for a blood test to conclusively find out whether you are deficient or not. However, general consensus is that taking vitamin D over winter months in the UK is fine.