Are polyphenols truly beneficial?

EATING fruit or having a glass of red wine is seen as offering health benefits. The benefits are often pinned on polyphenols, natural chemicals—found in foods—referred to as flavonoids and phenolic acids, but also fragments of food proteins called peptides. Until recently, there were a large number of food and beverage products containing polyphenols and peptides that were making health claims, but evidence has been lacking.

Now, scientists in Europe are to run experiments and clinical trials to work out what beneficial effects polyphenols and peptides can have on cardiovascular disease risk and also how they cause these effects, under the EU-funded BACCHUS research project. Examples include potentially healthy polyphenols from apples, pomegranates and oranges, and peptides found in certain wheat varieties and in specially processed eggs, as well as peptides produced during the dry-curing of pork meats.
Paul Kroon, Ph.D., project coordinator at the Institute of Food Research, Norwich, UK, hopes to see European food companies making health claims for heart health on their label which is backed up by clinical trials and evidence from the lab showing what is happening in the body. 

The benefits of polyphenols are well-known but they may not be as easy to harness, according to experts. “There is good evidence, both from basic research and human studies that certain polyphenols can improve blood vessel relaxation and lower blood pressure in patients with heart disease and/or hypertension,” notes Balz Frei, Ph.D. of the Linus Pauling Institute at Oregon State University, USA.  

However, he adds that polyphenols are not nutrients and are generally poorly absorbed. “The small amount that makes it into the body is rapidly metabolised and excreted in urine and bile. This is very different from vitamins and micronutrients, which the body needs for normal function and survival.”

The rationale for the project is to avoid misleading claims on product containing such active substances. “It is important that consumers are protected from health claims that are not supported by good science.” It is a challenge to tease out which compounds are causing which effects. Until last year, many products came with health claims, for example related to heart health, but the European Union cracked down on unsupported claims in September 2012.

Dr Kroon hopes that the participation of food companies in the project will improve the design of the trials and provide access to improved foods for testing. “In my view a lot of claims made about certain products were difficult to substantiate,” he adds. “Making a claim for example that foods have lots of antioxidant activity when measured in the laboratory is not sufficient, it is necessary to demonstrate that consumption of this food causes a measureable benefit in the body.” 

The trouble, Dr Frei tells youris.com, is that numerous companies, especially in the neutraceutical field, have made unsupported or misleading claims about polyphenols. “One of them is the ‘high antioxidant value’ of ‘superfruits’ as measured by the so-called ORAC assay, and how this high antioxidant content will trWomens Running Shoes