Professor Jack Vanden Heuvel, co-director of Penn State's Center of Excellence in Nutrigenomics, has suggested that incorporating CLA as a dietary supplement or from enriched foods, in addition to a balanced diet, could be a suitable way of helping diabetics control their blood glucose and insulin levels.
CLA are found predominantly in dairy products such as milk, cheese and meat, and are formed by bacteria in ruminants that take linoleic acids – fatty acids from plants – and convert them into conjugated linoleic acids, or CLA.
The benefits of CLA supplementation for diabetics is not new, with studies with the rat model for diabetes, called the Zucker fatty rat, producing a 50 percent reduction in glucose and insulin.
Improvement in eight weeks
Despite human intervention trials producing mixed results, said Vanden Heuvel, generally eight weeks of CLA supplementation in type-2 diabetics can lead to improvements.
“The eight-week number that was quoted actually comes from examining the review articles on the human studies. By eight weeks of CLA [supplementation] you see a reduction in body fat (in most studies); since body fat is causally related to diabetes, I interpret this to mean that there is an improvement in diabetes,” Vanden Heuvel told NutraIngredients.com.
Prof Vanden Heuvel said however that no studies have shown a decrease in glucose utilisation in humans given CLA supplements, highlighting a need for a large, long-term clinical study to examine the effects of CLA supplements on human health.
The mechanism behind these benefits is said to be similar to anti-diabetic drugs, said Vanden Heuvel, and works by triggering a set of nuclear receptors called PPAR, with the biological purpose to sense fatty acids and fatty acid metabolites within the cell, and increase the tissues' sensitivity to insulin.
"Anti-diabetes drugs act the same way. They mimic the natural activators of the receptors by getting into the cell and interacting with the PPARs to regulate glucose and fat metabolism," said Vanden Heuvel.
"And compared to the synthetic drugs used to treat this disease, CLA does not cause weight gain and may in fact decrease overall body fat," said Vanden Heuvel.
Despite such promising results, several challenges remain, said Vanden Heuvel.
“[Firstly], showing that there is true, clinical efficacy of CLA in treating diabetes. Rat models are great for testing a hypothesis, but they may not reflect what happens in humans.
"[Secondly], there is more than one 'CLA'. This term refers to a lot of isomers and each isomer may have a different biology. Some of the studies done on diabetes were performed using a purified isomer whereas others use a mixture of CLA isomers. This makes interpretation difficult.
“[Finally], how can we incorporate this information into a healthy lifestyle? Should we encourage consumption of dairy products or are we talking about a dietary supplement? We need more research to address all of these issues.” - (Decision News Media, August 2006)
A-Z of CLA