As we will learn in this post, supplementing with vitamin D while eating a higher fat diet may help to increase vitamin D levels, but also may have an impact on short term symptoms of heart health, such as heart palpitations in some individuals.
Sun derived vitamin D vs. supplements
Vitamin D is mainly obtained through exposure to sunlight, generated by the cells of the skin, but a small amount can also be ingested through supplements.
Previous studies have shown that vitamin D synthesized in the skin is carried in the blood by a protein known as vitamin D binding protein (VDP). It was assumed that dietary or supplementary vitamin D was carried in the same fashion. However, researcher has shown ingested vitamin D is preferentially carried by various lipoproteins, allowing it to pass from the stomach into the blood supply.1
More recent work has suggested that VDP may associate with lipoproteins as well.2 Interestingly, it seems that when vitamin D alone binds with lipoproteins it is much more readily used, whereas when associated with VDP and lipoproteins it demonstrates a weaker but much longer lasting effect.1 So, for our purposes here, we see that vitamin D derived from sun exposure lasts longer in our systems than does supplemental vitamin D.
Vitamin D impact on lipids
Several studies have investigated vitamin D and blood lipids.
In 2007, a study showed a positive correlation between vitamin D and total cholesterol (when cholesterol in the blood increases, so does detected vitamin D).3 Two years later another study demonstrated that, when exposed to UV radiation, volunteers with high baselines levels of total cholesterol produced significantly more vitamin D, which is shown in the graph below.4
This graph shows that the amount of vitamin D produced after exposure to UV radiation (mimicking exposure to the sun) was greater in volunteers with a high baseline level of cholesterol.
Both of these papers focus on vitamin D production in the skin. As cholesterol is broken down into a vitamin D precursor the link is easy to see. As far as I was able to determine, there have been no studies looking at the link between a high baseline level of blood lipids (especially cholesterol) and vitamin D supplementation.
Vitamin D and heart issues
One hypothesis is that elevated blood lipids results in greater absorption of vitamin D from the gut, and carry more vitamin D generated in the skin, increasing the level of vitamin D detected in the blood.
Muscle relies on a steady supply of calcium ions in order to contract. In the heart this contraction results in the heartbeat; a uniform contraction of the entire muscle which pumps blood around the body. However, if too much calcium is present in the blood, excessive or irregular muscle contractions can occur; in the heart this can manifest itself as an irregular or racing heartbeat.6
Vitamin D genes
Finally to the genetic element of all this. We know there are some SNPs related to a poor lipid outcome i.e. increased LDL levels in the blood, however the exact mechanism is poorly understood and further research is required.
What we do know however is that SNPs in the vitamin D receptor (VDR) gene can lead to enhanced vitamin D activity. Several studies have shown that the shorter VDR protein, produced by the presence of the rs2228570 (FokI) ‘C’ allele is more transcriptionally active. This means that given the same levels of vitamin D someone with the short ‘C’ allele VDR protein will display increased expression of vitamin D dependent genes.78 This increased activation of vitamin D dependent genes results in a greater uptake of calcium from the intestine.910
|Protein||Gene||SNP ID (Traditional name)||Major Allele/Minor Allele (Risk)||Effect|
|Vitamin D Receptor||VDR||rs2228570 (FokI)||T/C||When carrying the C allele, VDR induces a greater effect when vitamin D binds. Resulting in increased calcium uptake|
We don’t currently know if this VDR polymorphism can be linked with heart health. Whilst there are anecdotal reports of people with various VDR gene polymorphisms reporting a racing or irregular heartbeat, there are currently no scientific reports confirming this effect.
Several studies have looked at longer term heart health in association with VDR gene polymorphisms. In a Chinese population, the rs2228570 (FokI) ‘C’ allele was associated with a reduced risk of coronary heart disease (8), although several other studies did not observe a similar protective effect.910
Bringing the hypotheses together
- Eating a higher fat diet can elevate blood lipids in some people.
- Elevated blood lipids results in greater absorption of vitamin D from the gut, and carry more vitamin D generated in the skin, increasing the level of vitamin D detected in the blood.
- Increased levels of vitamin D in the blood lead to increased calcium levels, which may induce an irregular or racing heartbeat.
- Those with a risk alleles for poor blood lipid composition, or vitamin D absorption (e.g rs2228570 ‘C‘) may be at risk of short term cardiac issues following high doses of lipids as characterized by MCT oil, Bulletproof Coffee or other fat derived supplements.
This is hypothesis only – however, those with the risk alleles discussed above and in previous posts may be wary of diets advocating extreme fat intakes, especially when supplementing with vitamin D.