South Africa has over 2,500 hours of sunshine per year. We live outdoors. We swim. We braai. We hike. So it would be reasonable to assume that vitamin D deficiency isn’t something we need to worry about.
And yet, it’s the single most common deficiency I find in my practice.
Why South Africans Are Still Vitamin D Deficient
The assumption that sunshine equals sufficient vitamin D is widespread, but it doesn’t hold up. There are several reasons why so many South Africans, even those who spend time outdoors, are running low.
Firstly, the amount of vitamin D your skin produces depends on far more than just sun exposure. Skin pigmentation plays a role: darker skin requires significantly more sun exposure to produce the same amount of vitamin D as lighter skin. Sunscreen use also blocks the UVB rays needed for vitamin D synthesis. And many people, particularly those working office jobs, simply aren’t getting as much direct sun exposure as they think.
Secondly, even with adequate sun exposure, some people don’t convert or absorb vitamin D efficiently. This can be influenced by body composition, gut health, age, and genetic variation.
And thirdly, the reference ranges used to define “normal” vitamin D levels are, once again, set conservatively. A level of 30 nmol/L might keep you out of the “deficient” category, but the evidence increasingly supports that optimal levels sit closer to 75 to 100 nmol/L.
What Vitamin D Actually Does
Vitamin D is not really a vitamin at all. It’s a hormone precursor, and it influences far more than just your bones. Adequate vitamin D is involved in immune regulation, mood and mental health, muscle function, cardiovascular health, insulin sensitivity, and even gene expression.
When I find a patient with low or sub-optimal vitamin D, I don’t just tell them to “get more sun.” I prescribe a structured replacement protocol and then recheck to make sure we’ve actually moved the needle.
It’s Not Just Vitamin D
While vitamin D is the most common deficiency I encounter, it’s far from the only one. There are a handful of nutrient deficiencies that I see again and again, often flying under the radar.
Iron
Iron deficiency (particularly low ferritin) is epidemic in menstruating women and is routinely dismissed when levels fall in the low “normal” range. Fatigue, hair loss, brain fog, breathlessness, and restless legs should always prompt a full iron panel, not just a haemoglobin check.
Vitamin B12
When I find a low vitamin B12, I don’t simply prescribe a supplement and move on. I investigate why it’s low. Vitamin B12 deficiency can be dietary (particularly in vegans and vegetarians), but it can also be caused by pernicious anaemia, medications like metformin or proton pump inhibitors, or conditions affecting the gut like coeliac disease or inflammatory bowel disease.
If you replace B12 without asking why it’s low, you may be masking an underlying condition that needs its own management. A responsible approach means testing intrinsic factor antibodies and gastric parietal cell antibodies when B12 is low.
Folate
Folate deficiency often coexists with B12 deficiency and can contribute to fatigue, mood changes, and in women of reproductive age, carries significant implications for pregnancy outcomes.
Magnesium
Magnesium is involved in over 300 enzymatic reactions in the body. Deficiency is common and underdiagnosed, partly because standard serum magnesium testing has limitations. Only about 1% of your body’s magnesium sits in the blood, so serum levels can appear normal even when total body stores are depleted. For a more accurate picture, I include RBC magnesium, which reflects intracellular levels more reliably.
The Bigger Picture
Nutrient deficiencies rarely exist in isolation. A patient who is low in vitamin D may also be low in iron and B12. A patient with fatigue and brain fog may have sub-optimal levels across several nutrients. Looking at the whole picture, rather than testing one thing at a time, is what allows us to address the root cause rather than chasing individual symptoms.
This is the heart of investigative blood analysis. It’s not about running every test under the sun. It’s about running the right tests, interpreting them in context, and then actually doing something meaningful with the results.
The Bottom Line
Living in a sunny country doesn’t protect you from vitamin D deficiency. Eating a “balanced diet” doesn’t guarantee adequate B12, folate, or magnesium. And when a deficiency is found, the question shouldn’t just be “how do we replace it?” It should be “why is it low in the first place?”
That second question is the one that changes outcomes.
Dr Robyn Bradfield is the founder of Bloodfields, a virtual investigative blood analysis practice. If you’d like a thorough assessment of your nutrient status, you can book through our website.