Grapefruit: Which to choose the red or yellow?

Something Extra

So you’re browsing the colorful stalls in the produce section of your favorite market, and you come across a selection of yellow grapefruit stacked beside a similar pile of red grapefruit. Which to choose?

A new study conducted by an international team of researchers from Israel, Singapore and Poland might help make your decision a little easier.

A second chance

Nearly sixty subjects were recruited for the study, led by researchers at the Hebrew University-Hadassah Medical School in Jerusalem. All of the subjects had several things in common; each had undergone recent coronary bypass surgery, each had high cholesterol levels, and each had used a cholesterol-lowering statin drug with no success. At the outset of the study, none of the subjects had taken any statins for at least 30 days.

The subjects were divided into three groups. For the duration of the 30-day study, each group followed the same low-fat diet, with a single variation: One group ate one yellow grapefruit every day, while another group ate one red grapefruit daily. No grapefruits were eaten in the third group.

After measuring cholesterol levels and antioxidant activity in all subjects before and after the trial period, researchers found no change in cholesterol levels among those in the group that ate no grapefruit. But total cholesterol and LDL cholesterol were both lowered in the grapefruit groups, most impressively among those who ate red grapefruit.

Remember: all these patients had tried lowering their cholesterol with statins. The drugs didn’t do the trick, but it appears that grapefruit did!

In addition, triglyceride levels dropped in the red grapefruit group, but neither of the other groups. As I’ve noted in previous e-Alerts, triglycerides are blood fats that can leave deposits in coronary arteries, increasing heart disease risk.

In their conclusion to the study, researchers noted that “fresh red grapefruit contains higher quantities of bioactive compounds and has significantly higher antioxidant potential than blond grapefruit.”

Benefits abound

If the subjects in the Hebrew University study continue to eat a red grapefruit every day, they may enjoy several other healthy benefits in addition to lowering heart disease risk.

In the e-Alert “Pass the Pamplemousse” (3/9/04), I told you about a study from Scripps Clinic In San Diego. A group of 100 obese subjects were divided into three groups: one group ate half a grapefruit before each meal, one group drank a glass of grapefruit juice before each meal, and one group was instructed not to eat any grapefruit or drink any grapefruit juice for the three-month study period. Aside from these instructions, all subjects continued their normal diets.

Results showed that those who ate a grapefruit with every meal lost an average of 3.6 pounds. Subjects in the grapefruit juice group lost an average of 3.3 pounds. A few subjects in both of these groups lost nearly 10 pounds. Meanwhile, the average weight loss in the group that consumed no grapefruit was less than one pound.

Subjects who ate grapefruit also showed better management of insulin levels. Glucose and insulin were measured before and after the study. When the trial was completed, those in the two grapefruit groups had lower levels of insulin and glucose than they did at the outset, while levels in the non-grapefruit group were unchanged.

The Scripps researchers believe that enzymes in grapefruit help control insulin spikes that occur after a meal, which frees the digestive system to process food more efficiently. The result: Less nutrients are stored as fat.

One word of caution: consumption of grapefruit and grapefruit juice may interfere with certain medications, so talk to your doctor or an experienced nutritionist before making grapefruit a part of your daily diet.

“Red Grapefruit Positively Influences Serum Triglyceride Level in Patients Suffering from Coronary Atherosclerosis: Studies in Vitro and in Humans” Journal of Agricultural and Food Chemistry, Vol. 34, No. 5, 2/3/06,
“Grapefruit May Improve Cholesterol” Miranda Hitti, WebMD Medical News, 2/10/06,
“Grapefruit Diet: Fact, Not Fiction” Scripps Clinic Press Release, 1/26/04,