Vitamin D Supplementation Is A Double-Edged Sword

Low serum vitamin D levels have been linked to higher risks of heart disease, cancer, falls, COVID, dementia, C. Diff, and others. And yet when we actually do randomized trials of Vitamin D supplementation — the thing that can prove that the low level was causally linked to the outcome of interest — we get negative results.

Vitamin D supplementation

A new randomized trial shows it can reduce the risk of cancer, while increasing the risk of heart disease.

Imagine, if you will, the great Cathedral of Our Lady of Correlation is Not Causation. You walk through the majestic oak doors depicting the link between ice cream sales and shark attacks, past the rose window depicting the cardiovascular benefits of red wine, and down the aisles frescoed in dramatic images showing how Facebook usage is associated with less life satisfaction. And then, you reach the altar. The holy of holies. Where, emblazoned in shimmering pyrite, you see the patron saint of this church. Vitamin D.

Low serum vitamin D levels have been linked to higher risks of heart disease, cancer, falls, COVID, dementia, C. Diff, and others. And yet when we actually do randomized trials of Vitamin D supplementation — the thing that can prove that the low level was causally linked to the outcome of interest — we get negative results.

Trials aren’t perfect of course — and we’ll talk in a moment about a big one that had some issues. But we are at a point where we need to either be Vitamin D apologists — saying forget what those lying RCTs tell you and buy this supplement — (an $800 million a year industry by the way) — or conclude that Vitamin D levels are a convenient marker of various lifestyle factors that do associate with better outcomes — a marker of exercise, of getting outside, of eating a varied diet.

In addition to its primary benefits, research suggests that vitamin D may also play a role in:

• Reducing the risk of multiple sclerosis (MS). A 2018 review of population-based studies found that low levels of vitamin D are linked with an increased risk of MSTrusted Source.
• Decreasing the chance of heart disease. Low vitamin D levels have been linked to increased risk of heart diseases such as hypertension, heart failure, and stroke. But it’s unclear whether vitamin D deficiency contributes to heart disease or simply indicates poor health when you have a chronic condition.
• Reducing the likelihood of severe illnesses. Although studies are mixed, vitamin D may make severe flu and COVID-19 infections less likely. A recent review found that low vitamin D levels contribute to acute respiratory distress syndrome.
• Supporting immune health. People who do not have adequate vitamin D levels might be at increased risk of infections and autoimmune diseases, such as rheumatoid arthritis, type 1 diabetes, and inflammatory bowel disease

Research has shown that vitamin D might play an important role in regulating mood and decreasing the risk of depression.

A review of 7,534 people found that those experiencing negative emotions who received vitamin D supplements noticed an improvement in symptoms. Vitamin D supplementation may help people with depression who also have a vitamin D deficiency.

Another study identified low vitamin D levels as a risk factor for more severe fibromyalgia symptoms, anxiety, and depression

People with higher body weights have a greater chance of low vitamin D levels.

In one study, people with obesity who received vitamin D supplements in addition to following a weight loss diet plan lost more weight and fat mass than the members of the placebo group, who only followed the diet planTrusted Source.

In an older study, people taking daily calcium and vitamin D supplements lost more weight than subjects taking a placebo supplement. The researchers suggest that the extra calcium and vitamin D may have had an appetite-suppressing effect.

The current research doesn’t support the idea that vitamin D would cause weight loss, but there appears to be a relationship between vitamin D and weight.

Several factors can affect your ability to get adequate vitamin D from sunlight alone.

You may be less likely to absorb enough vitamin D from the sun if you:

• live in an area with high pollution
• use sunscreen
• spend most of your time indoors
• live in a big city where buildings block sunlight
• have darker skin (The higher the levels of melanin, the less vitamin D your skin can absorb.)

These factors can increase your risk of vitamin D deficiency. That’s why it’s important to get some of your vitamin D from non-sunlight sources.