Soy and fruit-enriched yoghurts could find an important role in the management of type-2 diabetes and high blood pressure, says new research from the US.
“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 characterised by spikes in blood sugar (hyperglycaemia) 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.
The new research, published in the Journal of Food Biochemistry, reports that the polyphenol content of fruit-enriched yoghurts, especially those made with blueberries or made from soy, may curb some aspects of diabetes.
How the study was done
The researchers bought commercially available peach, strawberry, blueberry and plain yoghurts (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 yoghurts had the second-highest concentrations of phenols (average 95 micrograms per millilitre) and the most antioxidant activity (radical inhibition of 90 percent). 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 percent and 52 percent of alpha-glucosidase and alpha-amylase activity, respectively.
Nonphenolic nutrient factor at play?
For ACE-I inhibition, however, the researchers report that there was more variation among the extracts, but in general the phenol-rich soy yoghurts were the best at inhibiting ACE-I (around 92 percent). 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 optimised phenolics phytochemical-enriched diets could have a role in developing complimentary strategies for type-2 diabetes and hypertension management.” - (Decision News Media, November 2006)