Recently, market analyst Mintel reported that sales of yoghurt in the UK are set to increase by 40 per cent over the next five years, and smashing the £2bn barrier by 2011, with surging functional yoghurt drinks driving sales.
"Cost-effective dietary changes are essential for fighting this disease, and traditional diets that have a higher content of these protective antioxidants are an important part of the solution. We should be able to use diet along with other therapies, and diabetes is a disease where this especially makes sense," said lead researcher Kalidas Shetty from the University of Massachusetts Amherst.
Type-2 diabetes is characterized by spikes in blood sugar (hyperglycemia) right after a meal, and is associated with many of the complications that can arise from the disease, including the failure of various organs such as the kidneys, heart, and eyes.
An estimated 19 million people are affected by diabetes in the EU 25, equal to four per cent of the total population. This figure is projected to increase to 26 million by 2030.
The new research, published in the Journal of Food Biochemistry, reports that the polyphenol content of fruit-enriched yogurts, especially those made with blueberries or made from soy, may curb some aspects of diabetes.
The researchers bought commercially available peach, strawberry, blueberry and plain yogurts (Dannon, Stonyfield, Stop 'n Shop, and Whole Soy) and tested the effects of these against enzymes typically targeted by diabetic medications (alpha-amylase and alpha-glucosidase), which slow the body's absorption of sugars. They also looked at the angiotensin-I converting enzyme (ACE-I), which plays a role in the constriction of blood vessels.
The UMass Amherst scientists found that the extracts from blueberry yogurts had the second-highest concentrations of phenols (average 95 micrograms per millilitre) and the most antioxidant activity (radical inhibition of 90 per cent). The soy yoghurt was found to have the highest polyphenol content (115 micrograms per millilitre).
In terms of alpha-glucosidase and alpha-amylase inhibition, Shetty and co-workers report that the blueberry yoghurts had the highest inhibitory effect, inhibiting, on average, 77 per cent and 52 per cent of alpha-glucosidase and alpha-amylase activity, respectively.
For ACE-I inhibition, however, the researchers report that there was more variation amongst the extracts, but in general the phenol-rich soy yogurts were the best at inhibiting ACE-I (around 92 per cent). The fruit content did not seem to influence ACE-I inhibition, unlike the other enzymes.
"This may indicate that a specific nonphenolic nutrient factor or specific peptides, could be relevant for enhanced ACE-I inhibitory activity," wrote the researchers.
However, the researchers noted that the yoghurts studied were all high in sugar, and the implications in terms of functionality are not clear. People with type-2 diabetes are typically advised to avoid eating sweet snacks.
Despite these unanswered questions, the researchers concluded: "This investigation indicates that properly optimized phenolics phytochemical-enriched diets could have a role in developing complimentary strategies for type-2 diabetes and hypertension management."