29. May, 2019

Cholesterol, phytosterols, and heart disease

I recently completed 6 months in a role where I was able to directly observe consumer eating habits.  I spoke with people about why they were making their food choices, and found that a key motivator was the prevention of heart disease. 

Cholesterol plays an important role in the production of vitamin D, hormones and bile, which is necessary for fat digestion. It is an essential part of every one of our cells, and our body produces it in the amounts that we need.  Studies show that cholesterol is unlikely to be the cause of heart disease, and it is still unclear if lowering it reduces the risk of developing the disease. 

Despite this, we continue trying to lower our 'bad' cholesterol levels using everything we have in our arsenal.  Today I am examining one of those weapons: phytosterols.  More commonly known as plant sterols, they work by competitively inhibiting cholesterol absorption. 

You have probably heard about plant sterol-containing margarines. Retailing at around $8 per 500g, they claim to help lower your 'bad' cholesterol levels if you eat a tablespoon each day, as part of a healthy diet.  That condition always amuses me, because it begs the question: If you are on a healthy diet, do you actually need this product? How much of the effect 'in conjunction with a healthy diet' is due to the product, and how much to better eating habits or the elimination of highly processed food? 

Western diets already contain very high levels of plant sterols thanks to the incorporation of vegetable oils in processed foods. The combined consumption of plant sterol-enriched products can actually lead to very high concentrations, which can affect the absorption of carotenoids and fat-soluble vitamins, constituting a hazard to children, pregnant and breastfeeding women.  

Western diets also contain high levels of saturated and trans fats through our large intake of meat, dairy products, and fried foods. So if we reduce our consumption of these, most of us will see a natural reduction in our cholesterol levels, without the need for expensive plant sterol-containing products. 

Researchers have also found data suggesting that in patients with the hereditary disease of sitosterolaemia (sitosterol is a plant sterol), epidemiological studies, and recent human cell and animal studies, plant sterols potentially lead to negative cardiovascular effects.  

Based on all of that (often conflicting) information, my recommendation is that you save your money and concern yourself more with the overall quality of your diet if you would like to reduce your risk of heart disease. 

Try to have a more whole foods, plant-based diet, reduce or preferably eliminate processed meat, and use good quality  olive oil. In that way, you will help moderate your cholesterol levels while also getting important nutrients lacking in margarine, such as fibre, vitamins, minerals and other beneficial phytochemicals such as antioxidants, which help reduce inflammation (common in people with heart disease). 

The health benefits of increasing your intake of plant-based foods far outweigh anything you can find in a highly processed food product such as margarine. 

References: 

Kuhlmann, K, Lindtner, O, Bauch, A, Ritter, G, Woerner, B, Niemann B 2005, 'Simulation of prospective phytosterol intake in Germany by novel functional foods' British Journal of Nutrition, vol.93, pp.377–385. 

Patel, MD, Thompson, PD 2006, 'Phytosterols and vascular disease', Atherosclerosis, vol. 186 pp.12–19. 

Weingärtner, O, Böhm, M, Laufs, U 2009, 'Controversial role of plant sterol esters in the management of hypercholesterolaemia', European Heart Journal, vol.30, no.4, pp.404–409.