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Grapefruit a risk to type 2 diabetes
08 Oct 2009
Sphumelele Mngoma

GRAPEFRUIT can be a serious risk for people with type 2 diabetes.

This is according to a pharmacologist at the University of KwaZulu-Natal whose findings are set to be published in an international scientific journal, Methods and Findings in Experimental and Clinical Pharmacology for 2009.

Dr Peter Owira’s research finding suggests that the simultaneous intake of grapefruit juice and metformin, the number one drug for type 2 diabe­tics, increases the build-up of lactic acid in the body.

This, he said, can result in too much acid in the blood or low pH levels, which may be fatal.

Speaking to The Witness yesterday, Owira, who lectures in pharmacology, said grapefruit juice is popular among patients with type 2 diabetes for its weight reduction properties because it is beneficial for lowering glucose in the blood.

He explained that obese people usually develop type 2 diabetes as a result of the hormone called insulin, which is produced by the pancreas to lower the amount of glucose and facilitates glucose uptake into the cells to allow for metabolic function.

“There are many metabolic consequences which come as a result of too much glucose in the blood, like renal failure. It can affect the blood vessels through cardiovascular diseases, which can lead to heart failure and strokes. It can even cause hypertension.

“Our results show that grapefruit acid taken simultaneously with metformin accelerates the uptake or the entry of the drug by the liver, which creates the build-up of lactic acid in the body.”

The metabolic reactions that keep the body alive require the body to be at a constant pH, he said, adding that the danger of a low pH or too much acid in the body is that it interferes with these functions and can be fatal.

Peter Owira presented his paper Grapefruit Juice improves glycaemic control but exacerbates metformin induced lactic acidosis in non-diabetic rat at College of Health Sciences research Symposium recently held at the Nelson R Mandela School of Medicine.

He tested the effects of grapefruit juice on glucose tolerance amongst metformin treated Wistar rats as part of his PHD research.

Three groups of rats were given different doses of grapefruit juice with one group also receiving a dose of metformin.

The results showed that both the group of rats given grapefruit juice along with those who had been administered metformin had lowered blood glucose levels. However, for those rats who had been treated for both glucose and metformin had significantly elevated blood lactic acid levels.

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