Revisiting the Grapefruit Diet

Grapefruit has a long history of association with various weight-loss regimens. Some of you might be old enough to remember “The Grapefruit Diet”; maybe you even tried it yourself, only to find after you quit that you quickly regained the weight you lost, and then some. But now a few recent findings have made me take a second look at this citrus fruit.

A possible weight-loss aid?

A study from the University of Western Ontario a few years back, for instance, suggested that an antioxidant compound in grapefruit called naringenin–it’s classed as a flavenoid, or plant-based bioactive molecule–might be capable of preventing weight gain, as well as decreasing the risk of diabetes and heart disease.

This research was conducted on two groups of mice, both of which were fed identical high-fat/Western diets with the exact same amounts of fat and calories. The mice in one of these groups, however (let’s call it Group 2), were also given high doses of naringenin, and the scientists found that their bodies were able to lower elevated blood levels of triglyceride (fat) and cholesterol. These Group-2 mice also didn’t develop insulin resistance and were able to normalize glucose metabolism.

By study’s end, the significant obesity usually seen in mice fed a high-fat/Western diet was entirely absent in the naringenin group. The Ontario researchers theorized that the compound grants these benefits by genetically reprogramming the liver to burn up extra fat instead of merely storing it.

Large doses needed to produce these results

It’s important to note that the animals in this study were administered much higher doses of naringenin than what you’d normally eat in your food. This compound, therefore, might turn out to be what’s called a nutraceutical, a natural substance found in food that, when it’s given in large pharmacologic doses, can cause specific or overall health benefits.

At any rate, the Ontario team plans to continue studying naringenin to find out if clinical trials in humans might one day be feasible. If so, they’ll be able to test whether the compound really does help with the treatment of obesity, as well as with other health problems such as diabetes and heart disease.

One more intriguing study

I’ve found one other report too by a research team studying naringenin, this one published online in the August 25 issue of PLoS One (Public Library of Science). The work involved collaboration between Harvard University, the Massachusetts Institute of Technology, The Center for Engineering in Medicine, and The Shriner’s Burn Hospital (Boston), as well as universities in both France and Israel.

The report states that naringenin might play a role not only in normalizing blood lipids (fats) in people with diabetes, but also in lowering high cholesterol and regulating weight. The researchers found that naringenin induced a “fasting-like” state in the liver cells of rats, which suggests that the compound might increase the oxidation of fatty acids. (They also said it might inhibit cells associated with hepatitis C.)

My take on these naringenin research studies

  • More research is needed but naringenin appears to be an antioxidant that might play a part in achieving a healthy weight, as well as in lowering the risks associated with some other diseases.
  • Regularly including in your diet the best sources of naringenin–namely, citrus fruits such as grapefruit, oranges, limes, and lemons–is a good idea since they can help increase the natural antioxidants in your diet.
  • Consider adding a high-quality antioxidant vitamin/mineral supplement to your diet (look for liquid or chewable supplements) to help decrease your risk of getting sick.
  • There are even dietary supplements available online now that contain naringenin, along with other bioflavenoids, or sometimes as part of a vitamin C supplement. Although this may sound like a great idea, these pills might not be for everyone (please see warning below).

And a warning

Please check with your doctor before adding grapefruit or grapefruit juice to your diet, since it should not be taken together with certain medications. (Ironically, some of the cholesterol-lowering drugs don’t do well with grapefruit.) This is because grapefruit juice contains substances that can interfere with the action of certain key enzymes in your intestinal wall and liver, enzymes responsible for breaking down particular drugs into forms the body can readily use and then get rid of. By changing how certain drugs are absorbed by the body, grapefruit can cause these meds to build up in the blood to potentially dangerous levels.