Grapefruit Benefits For Immune System, Gut, Skin, Weight Control

Grapefruit is famously juicy and tangy, with its yellow, pink or ruby flesh reaching peak ripeness in the winter months. The citrus gets a lot of buzz during cold and flu season and weight-loss season as people look for ways to be healthy in the new year.

But can eating grapefruit really help boost the immune system, burn fat or lead to a slimmer figure?

Here’s what to know about its benefits and impact on the body — plus important precautions about grapefruit’s interaction with medications.

Grapefruit, similar to other fruits, is a good source of vitamins, minerals and fiber, says Elisabetta Politi, a registered dietitian at the Duke Lifestyle and Weight Management Center in Durham, North Carolina.

“It’s what we call a nutrient-dense food, so it’s not high in calories, but it is high in the ratio of calories to micronutrients that may be advantageous for health,” adds Cynthia Thomson, Ph.D., a registered dietitian and director of the Zuckerman Family Center for Prevention and Health Promotion at the University of Arizona.

“Grapefruit can and potentially should be part of an overall healthy diet that’s based in plant foods.”

Grapefruit nutrition

Half of a pink or red grapefruit contains the following, according to the U.S. Department of Agriculture:

• 37 calories
• 9 grams of carbs
• 1.3 grams of fiber
• 0.7 grams of protein
• 45 milligrams of vitamin C

It also comes with some vitamin A, calcium, magnesium, potassium and phosphorus. Grapefruit naturally contains a lot of water, so it’s hydrating. It has no cholesterol and virtually no fat.

Bioactive compounds that may promote health — via antioxidant and anti-inflammatory properties — are more concentrated in different parts of the grapefruit, Thomson notes.

“In particular, (researchers) have been interested in the pith — that’s that white stuff that some people meticulously pick off when they eat citrus fruit,” she says. “But it actually has higher concentrations of some of these bioactive compounds.”

Does grapefruit boost your immune system?

Yes, since it contains lots of vitamin C, the experts say.

“A whole grapefruit provides nearly 100% of the recommended daily value of vitamin C, a powerful antioxidant, which can boost the immune system,” Politi tells TODAY.com.

It’s not unusual for Americans to have a diet low in vitamin C, so when a person who is borderline depleted gets an adequate amount of the nutrient, there will be an enhanced immune response that’s going to help protect them, Thomson adds.

“Does it have the power of a flu vaccine? No,” she says. “But these are all things we can do that are basically low cost and good for us on a lot of levels.”

The effectiveness of vitamin C in preventing colds hasn’t been proven, but several clinical trials suggest a decrease in their severity, Politi says.

Does eating grapefruit help with weight loss?

There’s been buzz about grapefruit’s purported ability to help people lose weight, but there’s no evidence for that, Thomson says.

She co-authored a study that instructed overweight and obese people to eat half a grapefruit before breakfast, lunch and dinner. After six weeks of this routine, they didn’t significantly lose weight compared to people in the control group who didn’t eat any grapefruit.

The participants who ate grapefruit three times a day did show a modest weight loss compared to their own starting weight, but Thomson wondered how long a typical person could keep up the routine.

“Think about your own life. Are you really going to eat half a grapefruit before every meal?” she notes. “The majority of Americans are not going to tolerate this very long. They’re not going to be able to keep it up.”

Grapefruit can help promote satiety if eaten before a meal “as kind of a preload” and help people eat less overall, just like any other food with fiber would, Thomson says. 

Does eating grapefruit burn belly fat?

There is no evidence that grapefruit, or any other food, can burn fat, Politi says. 

“However, as a nutritious, low calorie, satisfying choice, it can be part of a meal plan conducive to weight loss. I recommend grapefruit to those who enjoy its flavor,” she adds.

Grapefruit health benefits

Vitamin C in grapefruit helps promote collagen production, which supports skin health, registered dietitian Samantha Cassetty notes, including grapefruit on her list of the healthiest fruits.

Besides getting vitamins, fiber and hydration from the grapefruit flesh, it may be wise to eat the membranes separating each segment.

“Those membranes are rich in a type of dietary fiber called pectin, which is what we would call a viscous fiber,” registered dietitian Karen Collins told the American Heart Association.

“And that is the type of fiber that can help lower (bad) LDL cholesterol and seems to be what they call a prebiotic that helps to nurture the healthy bacteria in our gut.”

When it comes to grapefruit and cancer prevention, fiber also helps with bowel function — reducing the risk of colorectal cancer — and helps with hormone regulation, so it could potentially play a role in protecting against hormone-related cancers like breast cancer, says Thomson, who is a cancer prevention scientist.

Certain compounds in grapefruit may have anti-cancer properties.

“I certainly would tell my patients, ‘Yeah, let’s get some citrus into your diet,’” she notes.

“But I’m not a big proponent of ‘This magical food is going to save your life and prevent cancer.’ I’m a proponent of, ‘Let’s look at your overall diet. Let’s get a lot of variety of fruits and vegetables in there.’”

Grapefruit interaction with medication

Several medications such as statins and calcium-channel blockers shouldn’t be taken with grapefruit or its juice because of its enzyme-binding ability, which means the medications may pass from the gut to the bloodstream faster than usual, Politi cautions.

The list also includes some anti-anxiety drugs, antihistamines, corticosteroids and organ-transplant rejection drugs, according to the U.S. Food and Drug Administration.

The interaction may lead to more side effects, so always read the drug’s label or patient information sheet so see if it’s affected.

Best way to eat grapefruit

The dietitians recommend eating grapefruit as is, without sprinkling any sugar or salt on it.

Eat the whole fresh fruit rather than juicing it to get the fiber and full portfolio of health benefits.

Try to eat the pith and the membranes because that’s where many of the beneficial bioactive compounds are concentrated.

“Don’t be pulling all that off — it’s really good for you,” Thomson says.