Eating fresh, seasonal and local foods is encouraged by many dietary traditions, such as the Mediterranean diet. There is solid evidence that these foods lower the risks of cardiovascular and metabolic disease, cancer and cognitive decline. As these chronic diseases all include an activation of chronic inflammatory pathways and changes in the gut microbiota (the bacteria which live in our intestine), does an increased intake of plant-based foods improve health by suppressing inflammation and promoting a healthy gut microbiota? Disruption of prolonged inflammation by polyphenols in foods and a healthy gut microbiome with dietary fibre may also reduce age-related complications and improve tissue repair mechanisms.
The standard medicines for the treatment of inflammation include inhibitors of the arachidonic acid pathways such as the glucocorticoids and NSAIDs. However, foods also contain effective anti-inflammatory compounds. This suggests that functional foods, defined as foods which provide both nutrition and benefits to health, could reduce the symptoms of chronic inflammation.
Professor Lindsay Brown’s research group at the University of Southern Queensland is interested in harnessing the power of these functional foods to develop potential treatments for chronic diseases such as metabolic syndrome, which includes hypertension (high blood pressure), obesity and fatty liver, diabetes and insulin resistance, as well as inflammatory bowel disease (IBD), chronic kidney damage and osteoarthritis.
Purple fruit and vegetables
Recent research from Professor Brown and his team emphasises the use of whole foods in rat models of chronic human diseases, initially studying anthocyanin-containing fruits and vegetables. Anthocyanins, the compounds responsible for the blue, purple, red and orange colours seen in many fruits, show marked anti-inflammatory activities. The team explored whether symptoms of metabolic syndrome could be improved, using sources such as Queen Garnet plum, a new variety containing up to 10-times more anthocyanins than standard varieties. Queen Garnet plums fed to rats reduced the symptoms of metabolic syndrome produced by a diet high in saturated fats and simple sugars including fructose and sucrose. Further, Queen Garnet plums reduced symptoms of IBD in rats given dextran sodium sulphate as effectively as the standard treatment with sulfasalazine. Other sources of the same anthocyanin, cyanidin glucoside, such as purple carrots, Saskatoon berries, chokeberries and purple maize, were just as effective. The related anthocyanin, pelargonidin glucoside from strawberries, also reduced metabolic syndrome and IBD symptoms.
Indigenous fruits such as Davidson’s plum in Australia are potential sources of anthocyanins and other bioactive compounds. Professor Brown and his team showed that this fruit decreased signs of metabolic syndrome and, in additional studies, reduced obesity-induced degeneration of knee cartilage.
As these studies were in rats, the next step was to determine whether humans responded similarly to the anthocyanins. Professor Brown and his group explored whether Queen Garnet plum juice improved markers of inflammation in overweight subjects and reduced the mildly elevated blood pressure in these people. The findings showed that 12 weeks of Queen Garnet plum juice consumption reduced blood pressure, as well as fasting insulin and leptin concentrations which are often used as markers of metabolic health. Overall, this plum juice was just as effective as standard medications for lowering blood pressure and improving metabolic health in this participant group. Professor Brown highlights the importance of building on these findings with extended clinical trials in metabolic syndrome and other inflammatory diseases.
Foods grown in tropical areas such as rice, fruits and seaweeds are important components of traditional diets. Nutritious tropical fruits, such as mango, mangosteen, pineapple and avocado, may offer the same health benefits as anthocyanin-containing temperate fruits and vegetables.
Studies on potential health benefits of tropical fruits present more opportunities for identification of environmentally sustainable, cost-effective and commercially viable functional foods. One such example is mangosteen, whose pulp is often eaten but rind is largely considered a waste product, despite being used in traditional medicine for many years and proven to have higher concentrations of beneficial phytochemicals. Indeed, Professor Brown and his team conclude that fruit rind powder derived from mangosteen improved metabolic syndrome in rats by mechanisms including appetite suppression, anti-inflammatory effects and increased fat metabolism. This still leaves the pulp as a culinary sensation!
An important example of the extent of agricultural waste is in the production of coffee, mainly in tropical areas. Green coffee reduced signs of metabolic syndrome but an even more effective and readily available intervention was spent coffee grounds, a waste product around the world usually ending up in landfill. Spent coffee grounds reduced the cardiovascular, liver and metabolic changes of the high-carbohydrate, high-fat diet. Roasting coffee produces melanoidins, which act as prebiotics. Prebiotics are generally a type of dietary fibre, which feed the gut bacteria and promote growth of the ‘good’ bacteria that contribute to gut, metabolic and immune health. The intervention with spent coffee grounds increased the diversity of the gut microbiota, and the changes in gut microbiota correlated with the reduction in obesity and improvement in glucose tolerance and systolic blood pressure. So, the enjoyment of coffee as a beverage can be paired with the redirection of the waste product to improve our health.
The human diet in Japan, Korea, China, Vietnam and the Philippines has included seaweeds, which have been considered healthy for hundreds of years – but they remain under-utilised outside East Asia. Seaweeds provide a source of dietary fibre such as alginates and carrageenans. Rats supplemented with red seaweed showed decreased body weight, visceral fat, blood pressure and blood cholesterol. As with the anthocyanin studies, there was a reduction in the number of inflammatory cells that migrated into organs, supplemented by prebiotic effects to reverse the changes by the high-carbohydrate, high-fat diet on the gut microbiota.
These are only some of the many possible functional foods that could reduce the burden of chronic diseases such as obesity, hypertension, liver disease, IBD and osteoarthritis.
From their studies, Professor Brown and his team hypothesise that there are two major reasons for the benefits of the foods. Firstly, all of the effective interventions reduced the infiltration of inflammatory cells into the heart, liver and adipose tissue. Given that many of the diseases that the group is targeting are chronic inflammatory conditions, this may go some way to explaining their benefits. Secondly, many of the interventions contained prebiotics and the normalisation of the gut microbiome could be a powerful mechanism of action. Further biological actions may support these actions, such as appetite suppression.
However, it is important to bear in mind that, while most of these studies have been undertaken in rodent models, the effects that these foods have on human disease has not yet been determined. Initial but limited studies on humans suggest improved health outcomes, but these results need to be reinforced.
Sustainability and community projects
A varied diet, containing plenty of colourful fruits and vegetables, is the best approach for optimising health. Appropriate foods can be grown in most climates and may include indigenous plants, usually under-researched and under-utilised. The growing of health-giving plants can be a local initiative as the involvement of multi-national companies is not necessary. This community involvement in growing the food can then be extended by community involvement in producing and storing the food, possibly using techniques developed over millennia. Such community projects on functional foods can build in sustainability for both food and health. While the benefits of functional foods are intuitive rather than proven, what is not yet clear – but what studies from Professor Brown’s team and others are beginning to show – is: the extent of these benefits, the mechanisms for these beneficial effects of these foods in the body and which individual food components are most effective.
Chronic diseases, such as metabolic syndrome in developed countries, are disproportionally common in people from low socioeconomic backgrounds, who may not have the budget to include these foods regularly in their diet. This shows that further work is needed to make functional foods accessible to all, including by finding ways to use agricultural and food waste.
Producing and processing foods produces large amounts of waste. The biorefinery concept allows food products to be just one of many outputs from the growing of foods, leading to the eventual goal of zero waste from food production. The options are very broad, including the production of fertilisers, methane, bioplastics and biofuels, allowing economic benefits from materials that would otherwise be sent to landfill. Collaborations between researchers, engineers, business and governments could ensure optimal outcomes at reduced costs, so that these options remain feasible for local communities.
- Bhandarkar NS, Mouatt P, Goncalves P, Thomas T, Brown L and Panchal SK. (2020). Modulation of gut microbiota by spent coffee grounds attenuates diet-induced metabolic syndrome in rats. FASEB Journal, 34(3), pp. 4783–4797. Available at: https://doi.org/10.1096/fj.201902416RR [Accessed 03 Dec 2020].
- du Preez R, Paul N, Mouatt P, Majzoub ME, Thomas T, Panchal SK and Brown L. (2020). Carrageenans from the red seaweed Sarconema filiforme attenuate symptoms of diet-induced metabolic syndrome in rats. Marine Drugs, 18(2), p. 97. Available at: https://benthamopen.com/FULLTEXT/TOSSJ-10-160 [Accessed 03 Dec 2020].
- du Preez R, Wanyonyi S, Mouatt P, Panchal SK and Brown L. (2020). Saskatoon berry Amelanchier alnifolia regulates glucose metabolism and improves cardiovascular and liver signs of diet-induced metabolic syndrome in rats. Nutrients, 12(4), p. 931. Available at: https://doi.org/10.3390/nu12040931 [Accessed 03 Dec 2020].
- Ghattamaneni NK, Sharma A, Panchal SK and Brown L. (2020). Pelargonidin 3-glucoside-enriched strawberry attenuates symptoms of DSS-induced inflammatory bowel disease and diet-induced metabolic syndrome in rats. Eur J Nutr, 59(7), pp. 2905–2918. Available at: https://doi.org/10.1007/s00394-019-02130-1 [Accessed 03 Dec 2020].
- John OD, Mouatt P, Majzoub ME, Thomas T, Panchal SK and Brown L. (2019). Physiological and metabolic effects of yellow mangosteen (Garcinia dulcis) rind in rats with diet-induced metabolic syndrome. Int J Mol Sci, 21(1), p. 272. Available at: https://doi.org/10.3390/ijms21010272 [Accessed 03 Dec 2020].
- John OD, Mouatt P, Prasadam I, Xiao Y, Panchal SK and Brown L. (2019). The edible native Australian fruit, Davidson’s plum (Davidsonia pruriens), reduces symptoms in rats with diet-induced metabolic syndrome. J Funct Food, 56, pp. 204-215. Available at: https://doi.org/10.1016/j.jff.2019.03.018 [Accessed 03 Dec 2020].
- John OD, Mouatt P, Prasadam I, Xiao Y, Panchal SK and Brown L. (2020). Tropical foods as functional foods for metabolic syndrome. Food & Function, 11, pp. 6946. Available at: https://doi.org/10.1039/d0fo01133a [Accessed 03 Dec 2020].
- Bhaswant M, Brown L and Mathai ML. (2019). Queen Garnet plum juice and raspberry cordial in mildly hypertensive obese or overweight subjects: A randomized, double-blind study. J Funct Food, 56, pp.119-126. Available at: https://doi.org/10.1016/j.jff.2019.03.011 [Accessed 03 Dec 2020].
Professor Lindsay Brown is a pharmacologist researching functional foods as potential treatments for chronic diseases such as metabolic syndrome including hypertension, obesity and fatty liver, as well as inflammatory bowel disease, osteoarthritis and chronic kidney damage. He has around 230 peer-reviewed publications with over 10,000 citations.
The University of Southern Queensland (Australia), Advance Queensland (Queensland State Government)
Sunil Panchal, Oliver John, Ryan du Preez, Jessica Pahl, Naga Ghattamaneni, Nikhil Bhandarkar; other important collaborators include Nicholas Paul, Rocky de Nys, Peter Mouatt, Torsten Thomas.
Nikhil Bhandarkar determined the reversibility of metabolic syndrome in rats with green coffee, coffee components and coffee waste. This has led to his current studies at Ben-Gurion University of the Negev, Israel, on therapeutics to suppress NAFLD and metabolic disturbances.
Naga Ghattamaneni has expanded the understanding of the usefulness of anthocyanins in inflammatory disorders by demonstrating that they improve the structure and function of the gastrointestinal tract in rats with IBD. His current project emphasises functional foods in obesity-induced osteoarthritis.
Oliver John focused on tropical fruits, especially mangosteen and Davidson’s plum, demonstrating their effectiveness to attenuate cardiovascular, liver and metabolic changes in diet-induced metabolic syndrome in rats. He is interested in the potential of generating affordable functional foods from tropical fruit waste to attenuate metabolic syndrome.
Jessica Pahl has investigated components of Queensland-grown algae, such as fibre and antioxidant pigments, to alleviate complications of metabolic syndrome. Working with locally-grown algae could provide another high-value revenue stream to regional industries that are already growing algae for other purposes.
Sunil Panchal has developed expertise in characterising responses to functional foods and nutraceuticals in animal models that mimic human disease conditions. His current research focusses on characterisation of food wastes and product development from these food wastes.
Ryan du Preez has analysed the effectiveness of macroalgae, microalgae and curcumin to reduce diet-induced changes in cardiovascular and metabolic function, including in the gut microbiota, in rats. This will lead to further studies of these functional foods in humans to improve chronic low-grade inflammation.
Professor Lindsay Brown
School of Health and Wellbeing,
University of Southern Queensland (Ipswich campus) 4305,
T: +61 7 3812 6366