Vitamin D, otherwise known as the ‘sunshine vitamin’ is a hot topic. For years vitamin C has been recognised worldwide for how it boosts immunity and promotes good skin health. Now however, off the back of a wave of studies and media attention, the health benefits of vitamin D are very much in the spotlight.
What is vitamin D?
There are 2 forms of Vitamin D – D2 and D3. Both have been studied in great depths looking at how they are interlinked and what form might be more effective. This debate has resulted in mixed opinions. Vitamin D2, also known as ergocalciferol, is derived from plants, whereas vitamin D3 is typically derived from animals or produced when our skin is exposed to sunlight or UV rays.
Studies have shown that of the 2 forms, D3 has proven to be the more potent and biologically active form of vitamin D in all primate species, including humans. Evidence suggests that vitamin D3 is far superior to D2 in raising serum 25-hydroxyvitamin D levels (25(OH)D) where, in the kidneys it changes into an active form of vitamin D. The active form of vitamin D helps control calcium and phosphate levels in the body.
This study, and many others outlining other various benefits has led to D3 becoming the prominent form in commercial vitamin D3 supplements.
Vitamin D deficiency soars…
In recent years the media coverage of vitamin D has exploded largely in part as a result of as much as three-quarters of some global populations being deficient . In the UK, a recent survey showed that more than 50% of the adult population now have insufficient levels of vitamin D and that 16% have a severe deficiency during winter and spring when daylight hours are limited.
Many studies blame the lack of vitamin D on limited exposure to sunshine as over 90% of it is derived from exposure to sunshine. It is estimated that 30 minutes of sunlight exposure on the face and forearms is enough to generate around 2,000 International Units (IU) of vitamin D. The Institute of Medicine recommends getting between 600 and 800 IU every day whereas other institutes recommend higher levels. Typically commercial D3 supplements deliver between 1000 and 2500 (UI).
What foods contain vitamin D?
Vitamin D is one of 4 fat-soluble vitamins (A, D, E, and K). Typically, vitamin D3 is found in fish, fish liver oils, egg yolks and fortified diary and grain products. Excluding sunshine, most natural sources found in foods are derived from animals. For that reason, vegan diets tend to be low in vitamin D.
Vitamin D deficiency links
Vitamin D deficiency has been linked to an increased prevalence of diseases. Numerous studies have linked the lack of vitamin D to everything from rickets, through to metabolic disorders and cancer. The most well-known consequences to not having enough vitamin D are rickets in children and softening bones (osteomalacia) in adults.
Vitamin D and calcium are often paired because vitamin D speeds up the absorption of calcium, whilst boosting phosphate uptake from the blood by the bones. This benefits sufferers of an inherent disorder called familial hypophosphatemia, triggered through low levels of phosphate in the blood.
Other studies have linked the pairing of vitamin D and calcium to a lowered risk of developing certain types of cancer. However, taking vitamin D alone does not appear to reduce the risk.
In addition to bone health, taking vitamin D supplements has been linked to a reduction in cavities, a reduced risk of Multiple Sclerosis (MS), and a lower chance of developing respiratory infections. Research also suggests that older women who consume more vitamin D from foods or supplements tend to have a lower risk of developing rheumatoid arthritis.
Finally, research has shown that people with lower vitamin D levels are more likely to be obese than those with higher levels.
How can you tell if you’re vitamin D deficient?
As with all medical or health concerns, it’s important to consult your GP for help and advice on the topic. Typically a blood test will be taken to measure levels of vitamin D in the blood before drawing any conclusions.
However, it’s important to note that those who are at risk of vitamin D deficiencies also include people of ethnicities with darker skin. Your skin pigment acts as a natural sunscreen. Pigment levels are greater in darker skin where individuals may need as much as 10 times more sun exposure to produce the same amount of vitamin D as a person with lesser pigment or of Caucasian roots.
Obese and overweight individuals also have a higher risk of having reduced levels of vitamin D. As a fat-soluble vitamin, your body fat will consume vitamin D. Therefore, if you’re overweight or obese, you will need more vitamin D than a healthy BMI individual to overcompensate for the fat absorption. The same also applies for people with higher body weights due to muscle mass such as bodybuilders for example.
Finally, the tell-tale sign of vitamin D deficiency is feeling ‘down’. In winter, many of us suffer from Seasonal Affective Disorder (SAD). SAD is a form of depression that occurs during the winter months, probably in response to the fewer hours of daylight. Taking a vitamin D supplement can help boost your mood and help overcome feeling ‘blue’.
Whyte MP, Haddad JG Jr, Walters DD, Stamp TCB. Vitamin D bioavailability: serum 25-Hydroxyvitamin D levels in man after oral, subcutaneous, intramuscular, and intravenous vitamin D administration. J Clin Endocrinol Metab 1979;48:906–11
Demographic Differences and Trends of Vitamin D Insufficiency in the US Population, 1988-2004. Adit A. Ginde, MD, MPH; Mark C. Liu, MD; Carlos A. Camargo Jr, MD, DrPH.
Pearce SH, Cheetham TD; Diagnosis and management of vitamin D deficiency. BMJ. 2010 Jan 11;340:b5664. doi: 10.1136/bmj.b5664.