Investigating seaweed bioactives for protection against cardiovascular diseases
Do you know someone who has had a heart attack or stroke?
These conditions fall under the umbrella of cardiovascular diseases (CVD), diseases of the heart and blood vessels, and are the leading cause of death worldwide. In fact, over 30% of all deaths can be attributed to CVDs, which is of great concern because many of these deaths are premature and could have been prevented[1].
A common risk factor for CVD is the level of lipids (fats) in the blood. This includes total cholesterol, high- (HDL) and low- (LDL) density lipoprotein cholesterol and triglycerides. HDL cholesterol is sometimes called the ‘good’ cholesterol because it helps to reduce the risk of CVD, while LDL cholesterol is sometimes called the ‘bad’ cholesterol because it increases the risk of CVD. Research suggests that improving the ratio of HDL to LDL cholesterol can have protective benefits for CVD[1].
A class of bioactive compounds, called polyphenols, has the potential to moderate levels of cholesterol in the blood. Polyphenols are found in plants and are present in common foods such as coffee, tea, red wine, berries, cocoa and spices. However, a more environmentally sustainable source of polyphenols can be found in the sea[2].
Seaweeds are a rich source of polyphenols that offer a more environmentally sustainable solution. Compared with land-based plants, seaweeds produce a higher biomass per production area, require less fresh water, and can be cultured in the sea avoiding the need for herbicides and pesticides[2]. In fact, seaweeds are being used as a sustainable source of feed for livestock that helps to lower methane emissions[3]. Bladderwrack (Fucus vesiculosus) is a variety of seaweed that typically contains high concentrations of polyphenols found uniquely in seaweeds (approx. 6% dry weight)[4].
Dr Margaret Murray and colleagues conducted a clinical study to investigate whether consuming a polyphenol-rich Fucus vesiculosus extract (supplement) for 12 weeks could help to moderate cholesterol levels and other risk factors for CVD. What they found was that, compared with the placebo group, the group who received the supplement had a small but significant increase in their levels of HDL (‘good’) cholesterol, with no changes in any other CVD risk biomarkers.
These findings were different from previous literature[5], which has largely demonstrated reductions in LDL cholesterol following supplementation with polyphenol-rich seaweed extracts. As mentioned, improving the ratio of HDL to LDL cholesterol, either by increasing HDL cholesterol or decreasing LDL cholesterol, is an important protective factor for CVD. The increase in HDL cholesterol levels observed in this study may therefore have important implications for reducing the impact of CVD.
This is one of only a few studies to indicate an increase in HDL cholesterol levels following supplementation with polyphenol-rich seaweed extracts, and highlights a key outcome for further investigation. While this study focussed on one specific type of seaweed, other seaweeds such as Ecklonia cava, have shown promise for improving biomarker risk factors of CVD and should be further investigated for its ability to moderate HDL and LDL cholesterol levels[4,5]. You can read about the health effects of Ecklonia cava and other seaweeds here.
This is an exciting stepping stone to more research into the health benefits of seaweed polyphenols and how they can be used to provide protective benefits against CVD. In the meantime, including seaweed as part of a healthy and balanced diet provides a good source of protein, fibre and micronutrients[6].
By Margaret Murray
Dr Margaret Murray is a Research Fellow in the School of Chemistry and Teaching Associate in the Department of Nutrition, Dietetics and Food at Monash University. Her PhD research investigated the human health benefits of polyphenols from seaweed for the prevention and management of diabetes and cardiovascular diseases. Other research interests include investigating health impacts of food-based bioactives and exploring how food systems can be tailored to support human and environmental health. Access Margaret’s research profile here.
Publication information:
Margaret Murray, Aimee L Dordevic, Kate Cox, Andrew Scholey, Lisa Ryan, Maxine P Bonham. Twelve weeks’ treatment with a polyphenol-rich seaweed extract increased HDL cholesterol with no change in other biomarkers of chronic disease risk in overweight adults: A placebo-controlled randomized trial. The Journal of Nutritional Biochemistry. Volume 96, 2021, 108777, ISSN 0955-2863, https://doi.org/10.1016/j.jnutbio.2021.108777.
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References:
[1] World Health Organisation, Cardiovascular diseases fact sheet (https://www.who.int/news-room/fact-sheets/detail/cardiovascular-diseases-%28cvds%29).
[2] Buono S, Langellotti AL, Martello A, Rinna F. and Fogliano, V. Functional ingredients from microalgae. Food Funct. 2014, 5:1669–1685.
[3] Roque BM, Venegas M, Kinley RD, de Nys R, Duarte TL, Yang X, Kebreab E. Red seaweed (Asparagopsis taxiformis) supplementation reduces enteric methane by over 80 percent in beef steers. PLoS One. 2021 Mar 17;16(3):e0247820. doi: 10.1371/journal.pone.0247820. PMID: 33730064; PMCID: PMC7968649.
[4] Murray M, Dordevic AL, Ryan L, Bonham MP. An emerging trend in functional foods for the prevention of cardiovascular disease and diabetes: Marine algal polyphenols. Crit Rev Food Sci Nutr. 2018 May 24;58(8):1342-1358. doi: 10.1080/10408398.2016.1259209
[5] Murray , Dordevic , Bonham , Ryan L. Do marine algal polyphenols have antidiabetic, antihyperlipidemic or anti-inflammatory effects in humans? A systematic review, Crit Rev Food Sci Nutr. 2017 :DOI: 10.1080/10408398.2017.1301876
[6] Food Standards Australia New Zealand, Australian Food Composition database. Accessed on 17/06/2021. Available from: https://www.foodstandards.gov.au/science/monitoringnutrients/afcd/Pages/default.aspx
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