Grapefruit and Metformin May Have Ill Effects on the Body's pH Levels

Too much acid in the blood can cause low pH levels that interfere with the body’s metabolic functions.

| Oct 26, 2009

A South African university pharmacologist has found that simultaneous consumption of metformin and grapefruit juice raises lactic acid to dangerous levels in rats (and conceivably in people) with type 2 diabetes. Too much acid in the blood can cause low pH levels that interfere with the body's metabolic functions. Conceivably, says Dr. Peter Owira, a pharmacologist at the University of KawZulu-Natal, such low levels could be fatal.

Dr. Owira's research involved three groups of non-diabetic rats, each of which received a different dose of grapefruit juice. While two groups ingested juice only, a third group ingested both grapefruit juice and metformin.

Results showed that all three groups experienced lowered glycemic levels. The group receiving both juice and metformin, however, also developed what Dr. Owira calls metformin-induced lactic acidosis, a condition in which lactic acid levels climb to very high, and potentially dangerous, levels.

Dr. Owira notes that grapefruit juice is a popular drink among South Africans with type 2 because it assists in weight control and helps lower blood glucose levels. By itself, he says, grapefruit juice is fine. The problem arises when it is consumed in combination with metformin-a common occurrence because in South Africa, as in the United States, metformin is the number-one oral drug consumed by type 2s. Given the differences between rat and human metabolism, however, Dr. Owira does not directly recommend that type 2s curb their consumption of grapefruit juice. He will publish his findings in Methods and Findings in Experimental and Clinical Pharmacology for 2009, an international scientific journal.

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Grapefruit a risk to type 2 diabetes

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Posted by Anonymous on 3 November 2009

Per above article thanks for the "heads up" becuase I take Metformin regularly and once in a while I used to also eat pink grape fruit. Thank goodness I had no ill effects.

Posted by Anonymous on 4 November 2009

Grapefruit and Metformin May Have Ill Effects on the Body's pH Levels
Is it not true that Grapefruit turns alkaline in the body and not acidic like the tablet Metformin.
Dr. Owira notes that grapefruit juice is a popular drink among South Africans with type 2 because it assists in weight control and helps lower blood glucose levels.
Then a good choice is to stop taking Metformin which over prolonged use a person can develop heart complications, due to high acid levels in the body.

Posted by Anonymous on 6 November 2009

The conclusion is just not clear. Is he saying that since the rat's maetabolism is different, then it is not conclusive after all? Further, does this mean, not to take the grapefruit at the same time as the Metformin but can be at different times? As you can tell, I'm confused. Please clarify.
Alice Zyetz

Posted by Anonymous on 21 December 2009

I read elsewhere that the grapefruit effect stays in the body for up to 24 hours. If the medication is taken daily, grapefruit should not be consumed at all.

Posted by Anonymous on 28 December 2010

Is this just if you take metforman and grapefruit at the same time? What if I take metforman in the AM and consume grapefruit in the PM?

Posted by Anonymous on 19 June 2014

Is it ok to drink grapefruit juice while taking metformin, but not eating grapefruit? What's the difference. I was told I shouldn't take either..a little confused, and the same with orange juice,can I or can't I. Help to clarify

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