Written by: Lewis Wallis Edited by: Swathi Kumar & Natasha Barrow
After coming across phytosterols and phytostanols during my degree, I was intrigued by the growing evidence indicating therapeutic potential as anticancer agents. However, these compounds are not new and have been long known to help reduce cholesterol. This blog post will summarise the benefits of phytosterols and phytostanols and describe how they are marketed as functional food products. The aim of these products is to reduce cholesterol levels which are a risk factor for heart disease and are designed for those who need help with cholesterol level management.
What is cholesterol?
Cholesterol is a molecule that circulates the blood. The molecule is a sterol which functions to provide stability to our cells and has an integral part to play in the digestive tract, where it is an essential component of bile - an important substance which drives the breakdown and absorption of nutrients.
Even though cholesterol plays an important role in normal functioning of the human body, too much can be harmful. Increased levels can lead to a build-up of fat in the blood which can block blood vessels and prevent blood flow, increasing the risk of heart disease.
What are phytosterols and phytostanols?
Phytosterol may sound like a technical term, but I guarantee you will have come across such compounds without realising. The term has two parts, with phyto meaning plant and sterol describing the chemical structure. Therefore, the term can be used interchangeably with plant sterol. Essentially these compounds play a similar role to cholesterol, but only naturally occur in plants. Similar to animals, sterols provide the plant cell membrane with support and stability. Plant sterols are unsaturated compounds meaning that somewhere in the structure, they have at least one double bond between a pair of carbon atoms (e.g. sitosterol).
The closely related phytostanols have the same chemical structure but exist in a “saturated form”, meaning that the double bonds between carbon atoms have been broken and hydrogen atoms have been added (e.g. sitostanol). Although they have a similar structure, plant stanols exist in much smaller quantities in food. Still, this did not stop Benecol using them to build a product portfolio of cholesterol-lowering functional foods.
The widely accepted cholesterol-lowering effect can be attributed to structural similarity between the compounds and cholesterol. As both are absorbed in the intestine via the same transporter protein, plant sterols absorption leaves cholesterol sitting in the digestive tract. This prevents cholesterol from reaching the bloodstream reducing the risk of elevated levels.
Cholesterol-lowering functional foods
Benecol is a brand that produces spreads, yogurts and yogurt drinks which all incorporate phytostanols as an ingredient. In doing so they have created a portfolio of cholesterol-lowering foods which can help consumers manage their cholesterol levels.
Combining phytostanols with another functional group, called an ester, results in a compound with increased solubility which can be more easily incorporated into products. Esters are therefore more often added to foods and are the functional ingredient in Benecol products. As they have more stable interactions, the resulting Benecol products can withstand higher temperatures and can be used for cooking or baking. However, brands vary in the compounds they add and each have different properties which can alter the specific use of the final products. Unlike Benecol, plant sterols are added to a competitor Flora Pro-Activ. This product should not be used for cooking or baking as the molecules can break down due to heat, reducing their effectiveness.
Do phytosterol-containing functional foods lower cholesterol?
The highest phytosterol content can be found in vegetable oils, nuts and seeds at (200-500mg), with phytostanols generally at lower concentrations 0.5-1.5mg/100g. When added as functional ingredients to yogurts and spreads, much larger quantities over 2000mg/100g are used. They are then marketed as 'cholesterol-lowering' or 'proven to reduce cholesterol'. But can they really be effective?
Indeed, there is substantial evidence to support the cholesterol-lowering effect of phytosterol- and phytostanol-containing products. After rigorous scientific assessment by the European Food Safety Authority (EFSA), four health claims have been approved for use within the European Union and Great Britain, allowing products to emphasise the proven health benefit. Therefore, foods containing the compounds at sufficient quantities (1.5-3g) can communicate the potential to reduce heart disease risk.
Can I benefit from cholesterol-lowering products?
Statins are a group of medicines often prescribed to treat high blood cholesterol and reduce the risk of heart disease. Another valuable route for lowering cholesterol is by moderating your diet, which could include the use of these food products. If you are currently taking cholesterol lowering medication, you should check with your doctor whether such products are suitable.
If you are familiar with checking food labels, you may be surprised to find a bulky paragraph on the back of the pack. This information is required by food labelling regulations and including the following information is mandatory:
Who is not recommended to use the product?
For pregnant or breastfeeding women and children under the age of 5, there is no need to reduce blood cholesterol levels. Therefore, such products may not be nutritionally appropriate, and an indication is required to emphasise this on pack. Including this information is required to avoid misleading the average consumer into believing that without the product they will not be able control their cholesterol and therefore be at higher risk.
What is the future for plant sterols?
Ongoing research into phytosterols and phytostanols highlights other important health benefits including an anticancer effect, meaning they could have therapeutic potential. A recent meta-analysis - a study which combines all the available evidence - summarised how the most common phytosterol, beta-sitosterol, can reduce breast and colon cancer cell activity and prevent tumour development in animal models1. Further clinical trials in this area would help to understand how this result is translatable to humans. Does this mean that in the future we will see more approved health claims for these compounds? Will they be recommended in a clinical setting to reduce cancer risk or to supplement cancer therapy? Potentially, and with food products and supplements already on the market, these compounds can be delivered at a low cost and are already widely accessible.
To summarise, phytosterols have a proven track record of reducing cholesterol and can be a great way for people to help control their individual levels. However, products in this space are designed with the intention to support those who have elevated cholesterol levels and need help with control. Still, there's no harm done by consuming Benecol or other phytosterol-containing functional foods within the recommended amounts of 1.5-3g, so don’t be put off by what can seem like a complex back of pack paragraph, provided you incorporate it as part of a healthy and balanced diet.
References:
1Giorgia Cioccoloni, Chrysa Soteriou, Alex Websdale, Lewis Wallis, Michael A. Zulyniak & James L. Thorne (2020) Phytosterols and phytostanols and the hallmarks of cancer in model organisms: A systematic review and meta-analysis, Critical Reviews in Food Science and Nutrition, DOI: 10.1080/10408398.2020.1835820
EU Nutrition & Health Claims: https://ec.europa.eu/food/safety/labelling_nutrition/claims/register/public/
GB Nutrition & Health Claims:
https://www.gov.uk/government/publications/great-britain-nutrition-and-health-claims-nhc-register
EU FIC regulation (retained by UK law):
https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32011R1169&from=EN
NHS information page on statins: https://www.nhs.uk/conditions/statins/
Chemical structures: https://genesandnutrition.biomedcentral.com/track/pdf/10.1007/s12263-010-0182-x.pdf
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