Seaweed may lower cholesterol and aid blood sugar regulation

Australia enjoys one of the highest life expectancies in the world, with a ranking within the top 10 for both men and women (Australian Institute of Health and Welfare 2017). However, while we are living longer, we are not necessarily healthier. There are many Australians living with and losing their lives to heart disease and type II diabetes (Australian Institute of Health and Welfare 2017, Heart Foundation 2017). Chances are you know someone who has suffered one or both health conditions, and it is predicted that they are only going to become more common.

Populations in Japan, particularly Okinawa, historically have much lower levels of diseases such as heart disease, cancers, stroke and diabetes, than people of Western cultures. This reduced risk of disease is thought to be due, in part, to their nutrient-dense diet, which is particularly high in vitamins, minerals and phytochemicals (such as polyphenols).

Taking a leaf out of the cookbook of Okinawa residents, Monash Nutrition researcher Margaret Murray has delved into the world of seaweed, which is touted as having positive effects on cardiovascular health and blood glucose regulation. A compound found in seaweed, polyphenols, is what caught her attention.

‘Polyphenols are biologically active compounds found in plants and seaweed,’ Margaret explained. ‘They play a role in the natural defence system of these organisms, protecting against environmental factors, such as UV radiation, and herbivore grazing’. As humans, we consume polyphenols every day in foods such as coffee, tea, cocoa, red wine, berries and spices. Seaweeds are also a source of polyphenols (algal polyphenols). While there are many different types of polyphenols, seaweeds contain a class not found in other, terrestrial plants, called phlorotannins. This is due to the harsh and unique environments in which seaweed survive.

Polyphenols are best known for their antioxidant activity, but may have numerous health benefits including protective effects against hyperglycaemia (high blood sugar), and hyperlipidaemia (high cholesterol) which are all known risk factors for cardiovascular disease and diabetic complications.

We are only just beginning to investigate algal polyphenols in humans to determine their health benefits. But the evidence to date shows promise, indicating that they may help to lower total and low-density lipoprotein (LDL) cholesterol levels, a risk factor for cardiovascular disease (Choi 2015, Hernandez-Corona 2014, Shin 2012). They may also help with blood sugar control, a key factor for preventing and managing type II diabetes (Hernandez-Corona 2014, Shin 2012).

Margaret explains that ‘if we can show that they are effective, algal polyphenols may be used as a first port-of-call to help lower cholesterol levels in people’. Unlike many prescription medications, algal polyphenols are not associated with a long list of side effects.

While algal polyphenols may help in the management and prevention of cardiovascular disease and type II diabetes, it is not simply a matter of harvesting seaweed from your local beach. Margaret and her research team are continuing their research into the health benefits of seaweed and are investigating if taking a specially formulated seaweed supplement for 12-weeks can reduce cholesterol levels in people who are overweight.

Further information

The Department of Nutrition, Dietetics and Food at Monash University is currently running a 12-week intervention study to investigate whether taking a seaweed supplement can reduce cholesterol levels. We are currently looking for volunteers for this study. If you are overweight and concerned about your cholesterol levels, you can get involved by contacting Margaret (Margaret.murray@monash.edu, 9902 4199) or by visiting https://tinyurl.com/MonashSeaweed.

Margaret Murray is a researcher at the Department of Nutrition, Dietetics and Food at Monash University. You can follow Margaret on Twitter via @MargaretSMurray. The research team is also comprised of A/Prof Maxine Bonham, Dr Aimee Dordevic and Dr Lisa Ryan.