Do Plant Sterols Lower Cholesterol?

It’s no secret that the world is becoming more overweight and obese by the day. The twenty-first century lifestyle often includes diets high in saturated fat, smoking, a lack of physical activity and an abundance of alcohol. These factors are all major players when it comes to developing high cholesterol (and other cardiovascular diseases). One solution to lowering cholesterol you might have heard about is consuming plant sterols. So let’s get into it. Do plant sterols lower cholesterol?

First off, what are plant sterols?

In the simplest of terms, sterols are a group of compounds (when two or more different elements are bonded together) that all share a fairly similar structure. They are found in the cell membranes of animals, microorganisms (e.g. bacterium and viruses) and plants (Gordon, 2003). To the average Joe, this doesn’t mean anything, or really matter. But, to the millions of people around the world with high cholesterol, this is a way we can use some pretty awesome science to our benefit. But in short, plant sterols (also known as “phytosterols”) are a compound found in the cell membranes of plants.

How do plant sterols lower cholesterol?

The fact that sterols all have a relatively similar chemical structure (with each type of sterol having an ever-so-slight difference) is one of the reasons that makes them useful for lowering our cholesterol. Because fats don’t mix well with water (think about when fat rises to the top when you make a stew and you have to skim it off), they need to be transported by the little ‘fat taxis’ of the intestines, called micelles. Micelles will help transport the fats we eat, as well as fat-soluble vitamins (vitamins A, D, E and K), to our intenstinal walls where they can be absorbed (Thomson, 1971).

When plant sterols are eaten with other foods, they essentially compete with cholesterol from our food for a spot within these micelles, our little ‘fat taxis’. Imagine twenty people are waiting for a taxi. A taxi pulls up and all twenty people charge for the taxi but only four people can get in. The taxi driver doesn’t care which four people get in, just that four people (or sterols, in our case) get in so he can have a full taxi, drive off and drop these people off at their destination. This leaves a bunch of people still outside of the taxi who have to wander off and look for another taxi.

Maybe not an amazing example, but hopefully you get the idea. Those who have to wander off looking for another taxi are the cholesterol that didn’t get absorbed by a ‘fat taxi’ which would eventually get excreted in our faeces. What a… weird sentence. So in short, plant sterols compete with cholesterol for a spot in the ‘fat taxi’, resulting in less cholesterol being absorbed from our food, meaning less cholesterol in our blood. Pretty smart, huh?

How much plant sterols should I consume?

This is an important part to get right. If you don’t consume enough, you won’t see the benefits you’re after.

1.5 to 2.4g is the recommended amount of plant sterols you need to consume to see a cholesterol-lowering effect. But what does this look like in terms of amount of food?

Unfortunately, unless you ate copious amounts of specific foods that are high in plant sterols, it’s really difficult to get enough from foods that aren’t fortified with plant sterols (had them added in, like when breakfast cereals are ‘fortified with vitamins and minerals’). For example, vegetable oils are thought to be one of the best sources of plant sterols, and are thought to contain between 150-1231mg per 100g (this is equal to 0.15g to 1.23g). However, 100g of vegetable oil contains around 900kcal. So while they may be a good source, you would have to consume a lot of calories worth of vegetable oil to get the desired amount.

As such, some food companies have added plant sterols to their products.

What foods contain high amounts of plant sterols?

As I mentioned above, it’s very difficult to achieve the daily recommended amount of plant sterols from ‘normal food’ alone. A 2018 study looking into the sterol content of fruits and vegetables commonly consumed in Sweden (yes, I know, random – but there’s not much research on this!) found that the median sterol content in fruits and vegetables was 16mg/100g and 14mg/100g, respectively (Normén, Johnsson, Andersson, van Gameren & Dutta, 1999). So you’d have to eat a boat load to get enough plant sterols from fruit and vegetables. In addition, studies investigating the amount of plant sterols consumed in Indonesia and Sweden (again, yes, random) found that the median intake was between 229 and 291.76mg/day. Bearing in mind the minimum recommended dose is 1.5g or 1500mg/day, it’s clear that you really do have to go out of your way to seek out high sterol-containing foods if you’re going to get anywhere near that 1500mg target.

This is where the fortified foods come in. These are foods such as margarine spreads and drinks that have plant sterols added to them in high amounts, to make achieving that beneficial amount much easier.

These are foods such as:

– Benecol spread / Benecol yoghurt drinks / Benecol yoghurts

– Flora Pro-Activ spread

– Sterol-containing supplements

Note – Always read the label so you’re sure how much of that product you need to consume to achieve the desired intake of plant sterols. Also, I’m writing this from the UK, so if you’re not reading this from the UK, I’m not sure what’s available in your country. However, the labelling on “cholesterol-lowering” products that contain plant sterols should say how much sterols they contain.

If you’re unsure about anything, please consult your doctor.

Does it matter when I consume plant sterols?

One particular study found that, whether you consume all of your daily plant sterols in one meal, or spread your intake over the day (e.g. over two or three meals), it doesn’t matter when it comes to getting the cholesterol-lowering effects from plant sterols. It just matters that you have them everyday, and in the right amounts (the research I’m referring to used average sterol intakes ranging from 1.76g/day, to 2.5g/day). However, research has also found greater effects when taking plant sterols two times per day, and even greater effects when taking more than two times per day.

So, to summarise the above paragraph – Taking the recommended amount of plant sterols per day (1.5-2.4g/day) will give you some benefit if taken once per day, more benefit if taken over two points of the day, and even more benefit if taken over more than two points during the day.

A table from the research I’m referencing is shown below, but don’t worry if you can’t make much sense of it, what I said above summarises it.

(Trautwein, Vermeer, Hiemstra & Ras, 2018)

Conclusion

So the main point of this article was to answer the question, “do plant sterols lower cholesterol?”. And the answer is as many answers are in the world of science, “yes, but it depends”. Plant sterols do lower cholesterol, but only when taken in the appropriate amounts (1.5-2.4g). If you don’t get enough, you won’t see any benefit, however it’s recommended that you don’t consume too much either, as this can affect your ability to absorb fat-soluble vitamins. So in short, more sterols will not produce more of a cholesterol-lowering effect and can have a negative effect. In addition, if you’re someone who doesn’t need to watch their cholesterol, then, well, you really don’t need to be going out of your way to consume sterols.

If you have any questions/comments, please do put them in the box below – it would be great to hear your thoughts on this topic, or any questions you may have.

And just to reiterate, if you’re unsure about anything, please consult your doctor.

Cheers for reading!

References:

– Gordon MH. FATS | Classification. Encyclopedia of Food Sciences and Nutrition. Academic Press; 2003. 2287–2292 p.

– Martianto, D., Bararah, A., Andarwulan, N., & Srednicka-Tober, D. (2021). Cross-Sectional Study of Plant Sterols Intake as a Basis for Designing Appropriate Plant Sterol-Enriched Food in Indonesia. Nutrients. 13(2), 452. Retrieved from: https://doi.org/10.3390/nu13020452

– Normén, L., Johnsson, M., Andersson, H., van Gameren, Y., & Dutta, P. (1999). Plant sterols in vegetables and fruits commonly consumed in Sweden. European Journal of Nutrition, 38(2), 84–89. Retrieved from: https://doi.org/10.1007/s003940050048
– Thomson, R, G. (1971). Absorption of fat-soluble vitamins and sterols. Journal of Clinical Pathology. 5, 85-89. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1176264/

– Trautwein, E. A., Vermeer, M. A., Hiemstra, H., & Ras, R. T. (2018). LDL-Cholesterol Lowering of Plant Sterols and Stanols –  Which Factors Influence Their Efficacy?  Nutrients. 10(9), 1262. Retrieved from: https://doi.org/10.3390/nu1009126