The downside of Vitamin D supplements
Known as the ‘sunshine vitamin, Vitamin D makes a significant contribution to our general well-being. It helps to maintain healthy bones and teeth and in supporting immunity.
For some groups, Vitamin D deficiency can be a problem, and GPs may prescribe supplements to increase levels. These people tend to be in groups aged over 65, pregnant and breastfeeding women spend large amounts of time indoors, dark-skinned people, and children. Those living in geographies with weak sunshine may also find they have low levels of Vitamin D.
The benefits of having the right levels of Vitamin D have become well-known. And this has led to a tendency for the fit and well to start looking at supplements too.
However, overdosing with Vitamin D can be harmful.
New guidelines from the US Endrocine Society suggest that the people who may benefit from supplements are:
- Children 1-8 years to prevent rickets and possibly lower the risk of respiratory tract infections
- Pregnant women, to decrease the risk of maternal, foetal or neonatal complications
- Adults over 75, to lower mortality risk
- Adults with pre-diabetes, to reduce Type 2 diabetes risk
However, you can have too much of a good thing, especially if you don’t fall into any of these categories. Potential effects of taking ‘too much’ Vitamin D as a supplement could be:
- Hypercalcemia: excess Vitamin D increases calcium absorption, leading to dangerously high blood calcium levels, which can cause nausea, vomiting, weakness, and kidney stones.
- Kidney damage: over time, high calcium levels can lead to calcium deposits in the kidneys, potentially causing permanent kidney damage.
- Bone health issues: paradoxically, too much Vitamin D can weaken bones by increasing bone resorption.
- Heart problems: elevated calcium can also lead to cardiovascular issues like calcification of arteries, increasing the risk of heart disease.
- Gastrointestinal symptoms: symptoms like constipation, poor appetite, and frequent urination may occur.
In a well-publicised story from 2023, an 89-year-old died in the UK after being admitted to hospital with hypercalcemia, a condition where the blood is overloaded with calcium. The inquest concluded that he died from vitamin D toxicity, also known as hypervitaminosis D, as well as cardiac and kidney failure. The coroner ruled his death a ‘misadventure’ – accidental but also due to an action he deliberately took. The patient had been taking vitamin supplements for at least nine months before his death, and a test showed his vitamin D levels were at 380, the maximum level the lab could record.
For all these concerns though, specialists are still unsure about what the ideal level for Vitamin D is. As ever, we recommend talking about supplements with your healthcare provider before embarking on a course of supplements that you may not need and could even damage your health.
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