Type 2 Diabetes and Grapefruit!

Do you remember the grapefruit fad? Maybe you are not old enough to recall the time when losing weight by eating grapefruit at every meal was in all the tabloids (alongside the martinis and cream and tuna fish diets), but in the 1950′s, 1960′s, and 1970′s, grapefruit was the fad diet equivalent of today’s cabbage soup diet.

But it turns out there really was something to it. Six researchers at the Shriners Burn Hospital and Massachusetts General Hospital in Boston, working with researchers at Harvard and Hebrew University, have found that the chemical that makes grapefruit bitter changes how fat cells use and store fat.

The chemical that has the effect on fat cells is known as naringenin. There has already been a clinical study that found that people who take a concentrated naringenin supplement experience significant lowering of LDL (“bad”) cholesterol. This research team decided to see if the effects in the liver, where cholesterol is made, also occurred in fat cells.

What the scientists found was that the grapefruit chemical stimulated the genes that make the enzymes that burn fat and cholesterol. At the same time, naringenin stimulated the PPAR-alpha gene that triggers the burning of fat when we aren’t eating, and the PPAR-gamma gene that makes cells more sensitive to insulin and lowers blood sugar levels.

The diabetic drugs Actos and Avandia stimulate PPAR-gamma, but they don’t stimulate PPAR-alpha. They in effect lower blood sugar levels by shoving the sugar into fat cells. The chemical from grapefruit, on the other hand, lowers blood sugar levels by increasing insulin sensitivity, but it also activates fat burning genes in fat cells. The researchers said that eating grapefruit would have many of the benefits associated with long-term fasting, without the need for long-term fasting.

Grapefruit juice increases the bioavailability of certain drugs. It’s believed that one of the flavonoids in grapefruit… likely naringin… causes this. Check with your doctor if you are on oral medications to see if grapefruit will interfere with any of the medications he has prescribed for you. It turns out that grapefruit juice can directly or indirectly interact in important ways with a number of medications.

Here’s a short list of medications that could be affected:

  • Zoloft
  • BuSpar
  • Carbatrol
  • Tegretol
  • Neoral
  • Sandimmune
  • Prograf
  • Zocor
  • Mevacor
  • Lipitor
  • Nimotop
  • Sular
  • Procardia
  • Saquinavir

You may be wondering what it is that causes the interaction between the fruit and the medication. The answer is that enzymes in the fruit metabolize the drug too fast and can cause higher levels of the drugs in the blood than normal. This would result in the potential for serious side effects. You may need to eliminate grapefruit products from your diet. Simply taking your medication and grapefruit product at different times doesn’t stop the interaction.


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