Before I answer that question, let’s remember that each body compound has its purpose and cholesterol is no exception. It is essential for the structure of healthy cell membranes and for producing vitamin D and our sex and adrenal hormones, which keep our metabolism working efficiently. It is only when blood cholesterol becomes too high that it presents a problem.
So where does cholesterol come from?
Our liver makes most of our cholesterol, in fact only 20% comes from the food we consume. Foods that are high in saturated fat contribute to high cholesterol levels.
Cholesterol travels in the bloodstream in protein encapsulated particles called lipoproteins. Two of the many types of lipoproteins are low-density lipoprotein (LDL) and high-density lipoprotein (HDL). LDL transports cholesterol to tissues. HDL transports cholesterol away from tissues back to the liver for excretion.
Foods high in saturated fat and too low in unsaturated fat change the way the liver deals with cholesterol. When cells have taken up sufficient cholesterol and there is still cholesterol present in the blood, the receptors on our cells become resistant to it and don’t work so well. The result is that cholesterol accumulates in the blood and is deposited in arterial tissue forming plaques that narrow the arteries.
This is why paying attention to the relative levels of HDL to LDL cholesterol is important. Higher amounts of HDL will keep our tissues clear of excessive cholesterol. Too much blood cholesterol is particularly associated with heart disease and strokes.
Foods high in saturated fats
processed meat, such as sausages, burgers, bacon and kebabs
fatty meat, such as lamb chops
full-fat dairy products such as cream, milk, yogurt, cheese and ice-cream
fried foods
butter, lard, ghee, margarine, coconut oil, palm oil
chocolate, toffee, cakes, puddings and biscuits, pastries and pies
The British Heart Foundation has some tips on simple swaps to help make healthier choices where the above is concerned (reference below).
Other considerations
High cholesterol can also be triggered by a sedentary lifestyle, medical conditions and genetic predispositions. Research shows that diets high in fibre help regulate cholesterol.
Back to the main question…can our microbiome influence cholesterol?
Mice studies show that dietary interventions that increase the richness and diversity of the microbiome have been associated with a decrease in circulating cholesterol.
There are three possible ways that a balanced microbiome influences cholesterol levels:
1. Studies have shown that some species of bacteria convert cholesterol to a substance called coprostanol in the gut. Coprostanol cannot be absorbed into our blood stream and therefore the cholesterol bound to it is flushed out in our stool.
2. Some lactobacillus strains absorb cholesterol, possibly to strengthen their own cell membranes, although this is not clearly understood.
3. Cholesterol is a component of bile, which is made in the liver and plays an essential role in breaking down fats in the digestive system so that they can be absorbed. Most bile is reabsorbed into the blood to be reused. However, a small amount remains in the digestive system where bile loving species thrive on it, producing secondary bile acids. It is unclear how bile acids and secondary bile acids feed back to the liver to regulate bile production and hence influence circulating cholesterol, but it is thought that higher levels of secondary bile acids may reduce cholesterol levels.
It is complicated, but the bottom-line is that the evidence points to balanced microbiomes positively influencing cholesterol levels.
All this leads to another question!
Can probiotics reduce cholesterol?
Research has shown that probiotics help to reduce cholesterol by positively altering the gut microbiome. Beneficial bacteria contribute to the clearance of cholesterol by influencing the way bile acid works and thereby reduces its absorption. Probiotics also increase short chain fatty acids which help to suppress cholesterol formation in the liver and improve its metabolism.
Best tips:
Consistently choose a diet high in fibre to improve short chain fatty acid status
Include probiotic (fermented) foods
Pursue an active lifestyle
Watch the amount of saturated fat in your diet
Choose to bake, steam, grill or boil foods instead of frying them.
Use a small amount of healthy oil or fat spread made from vegetables or seeds.
Minimise butter and other animal fats.
Consider microbiome analysis to aid a targeted approach to promote the health of your microbiome.
Pictured here is a selection of healthy fats - olive oil, avocados, walnuts, sunflower and pumpkin seeds.
Melanie Kulkarni Ad Dip Nat is a registered Naturopath and Microbiome Group Associate. You can book appointments with The Microbiome Group practitioners here.
REFERENCES:
Elina S Momin et al. The Effects of Probiotics on Cholesterol Levels in Patients With Metabolic Syndrome: A Systematic Review April 2023. DOI10.7759/cureus.37567
Aurelie Cotillard et al. Dietary intervention impact on gut microbial gene richness. Nature 2013. https://doi.org/10.1038/nature12480
https://www.bhf.org.uk/informationsupport/risk-factors/high-cholesterol
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