Africans living in rural areas have been reported to have one of the highest levels of vitamin D in the world. This is not surprising given our wonderful sunny skies and warm weather. To be expected, you’d think, with our wonderful sunny skies and warm weather. What you wouldn’t expect, though, is that studies have also suggested that one in three Africans are vitamin D deficient1, the major cause being urbanisation. With the many roles that it plays in maintaining good health, we need to ensure that we get enough of this sunshine vitamin.
Why we need vitamin D
Vitamin D is essential for the growth and development of bones and teeth, and it helps with improved resistance to certain diseases. It’s a nutrient which the body produces when the skin is directly exposed to sunlight. Some of the key functions of vitamin D include:
1. Aiding calcium absorption in the gut; vitamin D sufficiency enhances calcium absorption by 30–40%.
2. Maintaining phosphate concentrations; it enhances phosphorus absorption by 80%.
3. Reducing inflammation by decreasing cell proliferation, increasing cell differentiation and stopping the growth of new blood vessels.
4. Modulating cell growth, neuromuscular and immune function, and glucose metabolism.
5. Regulating the function of 229 genes in the body.
Prolonged vitamin D deficiency causes rickets in children, a disease where the bone tissue fails to mineralize properly, resulting in soft bones and skeletal deformities. Severe rickets may also cause failure to thrive, developmental delay, hypocalcemic seizures, tetanic spasms, cardiomyopathy, and dental abnormalities.
Similarly, in adults and adolescents, vitamin D deficiency can lead to osteomalacia, the softening of adult bones due to defective mineralisation, also resulting in weak bones. Vitamin D deficiency also exacerbates osteopenia, osteoporosis, and fractures in adults.
Scientists have found that most tissues and cells have receptors for vitamin D, and are therefore investigating other functions of vitamin D beyond bone health. There’s growing research that supports the possible role of vitamin D against cancer, heart disease, hypertension, fractures and falls, autoimmune diseases, influenza, type-2 diabetes, and depression.
Sources of Vitamin D
The main source of vitamin D is sunlight. Vitamin D is found naturally in few foods. You can also get Vitamin D from supplements.
Sunlight. It’s difficult to provide guidelines on how much sunlight is necessary for adequate vitamin D intake since several factors affect vitamin D absorption, including wearing sunscreen (a sun protection factor of 30 reduces vitamin D synthesis by more than 95%), skin melanin content, age, cloud cover, latitude, season and time of day. Read more about it here – 8 Things you should know when getting vitamin D from the sun.
Food. Though few foods are naturally rich in vitamin D3, the best sources are fatty fish (salmon, tuna and sardines) and fish liver oils (cod liver oil). Smaller amounts are found in beef liver, egg yolks and raw mushrooms. In South Africa, a number of cereals and margarine are also fortified with Vitamin D. Vegans, ovo-vegetarians and people who have milk allergies or lactose intolerance tend to have diets low in vitamin D.
Supplements. Supplements can contain either vitamin D2 or vitamin D3 or both. Vitamin D2 (ergocalciferol) is plant-based and vitamin D3 (cholecalciferol), is animal-based. Though both forms are well absorbed in the small intestine, there is a debate as to which one is better; experts have preferred D3 as its naturally produced in the body.
Recommended dosage
In South Africa, the Recommended Daily Amount of vitamin D is 15 μg (600 IU) for adults, though the individual recommended dose depends on your age, gender, pregnancy and breastfeeding status.
Certain groups are at risk of having vitamin D inadequacy and may benefit from supplementation:
• People with dark skin, because the greater the amount of melanin in the skin reduces the skin’s ability to produce vitamin D from sunlight
• People who have limited sun exposure such as those who work nightshifts, cover their bodies for religious purposes or who are homebound
• The elderly, because the skin’s ability to synthesise vitamin D declines with age
• People with conditions that limit fat absorption, such as some forms of liver disease, cystic fibrosis, celiac disease, Crohn’s disease, and ulcerative colitis. Vitamin D absorption depends on the gut’s ability to absorb dietary fat.
• People who are obese or have undergone gastric bypass surgery
• Breastfed infants since human milk alone does not ordinarily provide infants with sufficient to meet vitamin D requirements
It’s fat-soluble, which means that it’s stored in the body. Too much vitamin D is toxic, but toxicity would come from supplementation not from excessive sun exposure. If you’re getting more than 2000 IU daily, then it can be toxic, leading to kidney stones or kidney damage, muscle weakness, or excessive bleeding.
Vitamin D supplements may interact with several medications, including statin medications, corticosteroids such as prednisone and some diuretics. Inform your health care professional if you are taking supplements with medication.
When choosing your supplement, always check if there is a full list of ingredients on the product, a package insert, a valid company address with contact details and compliance to Good Manufacturing Practices (GMP), which is a prerequisite for health product manufacturing. Click here for further info.
