Grapefruit: Health Benefits, Facts, Research

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The grapefruit was bred in the 18th century as a cross between a pomelo and an orange. They were given the name grapefruit because of the way they grew in clusters similar to grapes.

Grapefruits vary in hue from white or yellow to pink and red and can range in taste from very acidic and even bitter to sweet and sugary. Grapefruits are available throughout the year, but the popular Florida and Texas varieties are in season between the months of November and June. Florida is said to be the world’s largest grapefruit growing region. Popular varieties of Florida and Texas grapefruit include: Ruby Red, Pink, Flame, Thompson, White Marsh, Star Ruby, Duncan, and Pummelo HB.

Grapefruits are low in calories but are full of nutrients and an excellent source of vitamins A and C. Harvard Medical School states that grapefruit has a glycemic index of 25, suggesting that it does not significantly affect blood sugar and insulin levels. You can find out more about the nutritional breakdown of grapefruits in the nutritional profile section of this article.

Grapefruits support clear, healthy skin, can help to lower our risk for many diseases and conditions and may even help with weight loss as part of an overall healthy and varied diet.

This MNT Knowledge Center feature is written by our registered dietitian and nutritionist, Megan Ware, and forms part of a collection of articles about the health benefits of popular foods.

At the end of this article you will see links to recent research about grapefruit published by MNT. It is important to note that although we discuss the possible health benefits of grapefruit, grapefruit intake should be avoided when taking certain medications. Please read the health risks section on the second page of this article for more information on this.

Possible health benefits of consuming grapefruit

Grapefruit
Grapefruits vary in hue from white or yellow to pink and red and can range in taste very acidic and even bitter or sweet and sugary.

Consuming fruits and vegetables of all kinds has long been associated with a reduced risk of many adverse health conditions.

Many studies have suggested that increasing consumption of plant foods like grapefruit decreases the risk of obesity, diabetes, heart disease and overall mortality while promoting a healthy complexion, increased energy, and overall lower weight.

1) Weight loss

Grapefruit may not be a miracle weight loss food as touted in some previously popular fad diets, but consuming grapefruit as part of a healthy diet may just give you a little boost. The Scripps Clinic ‘Grapefruit Diet’ study, led by Dr. Ken Fujioka, monitored the weight and metabolic factors of 91 obese men and women for 12 weeks. Each participant was randomly assigned to one of four groups to receive either placebo capsules along with 7 ounces of apple juice, grapefruit capsules with 7 ounces of apple juice, 8 ounces of grapefruit juice with a placebo capsule or half of a fresh grapefruit with a placebo capsule three times a day before each meal.

After 12 weeks, the fresh grapefruit group had lost the most weight at 3.52 lbs, the grapefruit juice group had lost 3.3 lbs, the grapefruit capsule group had lost 2.42 lbs, and the placebo group had lost 0.66 lbs. According to the researchers, there was also a significant reduction in 2-hour post-glucose insulin level in the grapefruit group compared with placebo. Half of a fresh grapefruit eaten before meals was also associated with improved insulin resistance.

2) Stroke

According to the American Heart Association, eating higher amounts of a compound found in citrus fruits like oranges and grapefruit may lower ischemic stroke risk for women. Those who ate the highest amounts of citrus had a 19 percent lower risk of ischemic stroke than women who consumed the least.5

3) Blood pressure and heart health

The powerful nutrient combination of fiber, potassium, lycopene, vitamin C and choline in grapefruit all help to maintain a healthy heart.

One study found that a diet supplemented with fresh red grapefruit positively influences blood lipid levels, especially triglycerides. Researchers concluded that the addition of fresh red grapefruit to the diet could be beneficial for people with atherosclerosis wanting to lower their high lipid levels, especially triglycerides.

In one study, those who consumed 4069 mg of potassium per day had a 49% lower risk of death from ischemic heart disease compared with those who consumed less potassium (about 1000 mg per day).3

High potassium intakes are also associated with a reduced risk of stroke, protection against loss of muscle mass, preservation of bone mineral density and reduction in the formation of kidney stones.3

Increasing potassium intake is also important for lowering blood pressure because of its powerful vasodilation effects.

4) Cancer

As an excellent source of the strong antioxidant vitamin C as well as other antioxidants, grapefruit can help combat the formation of free radicals known to cause cancer. Lycopene intake has been linked with a decreased risk of prostate cancer prevention in several studies and foods high in vitamin C and beta-carotene have been shown to lower the risk of esophageal cancer in particular.

5) Digestion and regularity

Grapefruit, because of its water and fiber content, helps to prevent constipation and promote regularity for a healthy digestive tract.

6) Hydration

As one of the most hydrating fruits in the world made up of 91% water (just below watermelon) and full of important electrolytes, grapefruit is a great snack to have on hand to prevent dehydration.

7) Skin

The antioxidant vitamin C, when eaten in its natural form (in fresh produce as opposed to supplement form) or applied topically, can help to fight skin damage caused by the sun and pollution, reduce wrinkles and improve overall skin texture. Vitamin C plays a vital role in the formation of collagen, the main support system of skin. Hydration and vitamin A are also crucial for healthy looking skin, both of which grapefruits can provide.

However, it is worth taking note of a study published in June 2015 which suggests that consuming grapefruit juice in large amounts may put us at higher risk of melanoma – the deadliest form of skin cancer.

8) Asthma prevention

The risks for developing asthma are lower in people who consume a high amount of certain nutrients. One of these nutrients is vitamin C, found in many fruits and vegetables including grapefruit.

On the next page we look at the nutritional breakdown of grapefruit, ways in which to incorporate more grapefruit into your diet and the possible health risks associated with consuming grapefruit, including grapefruit’s interference with certain medications.

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Nutritional profile of grapefruit

According to the USDA National Nutrient Database, half of a medium pink grapefruit, (3 ¾ in diameter) contains approximately 52 calories, 0 grams of fat, 0 grams of sodium, 0 grams of cholesterol, 13 grams of carbohydrate (including 8.5 grams of sugar and 2 grams of dietary fiber), and 1 gram of protein.

Eating half of a grapefruit per day will meet 64% of your vitamin C needs, 28% of vitamin A, 2% of calcium and 2% of magnesium.

Grapefruits also contain small amounts of vitamin E, thiamin, riboflavin, niacin, folate, pantothenic acid, potassium, phosphorus, manganese, zinc and copper.

Not only are pink grapefruits high in common vitamins and minerals, they also pack a powerful antioxidant punch with lycopene and beta-carotene along with the phytonutrients limonoids and naringenin.

Studies have shown that fresh pink or red grapefruit contains higher quantities of bioactive compounds and has significantly higher antioxidant potential than white or yellow grapefruit.

How to incorporate more grapefruit into your diet

Grapefruits should be picked at their peak of ripeness because they do not ripen or improve in quality after being picked, unlike some other fruits. Grapefruits should be stored at room temperature, away from direct sunlight. Choose a grapefruit that is heavy for its size and has a little spring when squeezed.

While it’s sometimes hard to find good quality fruits and vegetables in the winter, it is the perfect time to buy citrus. Winter is the peak season for grapefruit, oranges and other citrus fruits.

Quick tips:

  • Keep a bowl on the kitchen table or counter stocked with fresh fruit from the season. Seeing the fruits readily available will likely cause you to choose them as a snack more often than raiding the cupboards for a less healthy snack
  • Grapefruit in salad
    Add some grapefruit slices to your salad at lunch or dinner.

  • Make a fruit salad with strawberries, pineapple, sliced grapefruit, mandarin oranges and grapes
  • Add some grapefruit slices to your salad at lunch or dinner. Compliment the oranges with walnuts or pecans, crumbled cheese and a light balsamic or citrus vinaigrette dressing
  • Make your own juice! Nothing tastes better than freshly squeezed fruit juice in the morning. When you make your own, you can be sure there are no added preservatives or sweeteners.

Check out some of these healthy recipes at home to help incorporate more grapefruit into your diet:

Pear-fect Grapefruit Smoothie
Grapefruit Yogurt Cake
Salmon Kebabs with Grapefruit and Quinoa Salad

Potential health risks of consuming grapefruit

Grapefruit intake should be avoided when taking certain medications, because of its enzyme binding ability. This means the medication can pass from your gut to your bloodstream easier and faster than normal. In many cases, these higher levels can be dangerous. Statin drugs, calcium channel blockers and psychiatric drugs are some of the most-common medications that interact with grapefruit.

For a list of specific medication-interactions with grapefruit, please see the table provided by The Harvard Medical School Family Health Guide.1

Also take caution when consuming grapefruit if you have a current kidney condition. Too much potassium can be harmful to those whose kidneys are not fully functional. If your kidneys are unable to remove excess potassium from the blood, it could be fatal.

Those with gastro-esophageal reflux disease (GERD) may experience an increase in symptoms such as heartburn and regurgitation when consuming highly acidic foods such as citrus fruit, however individual reactions vary.

Keep in mind that is the total diet or overall eating pattern that is most important in disease prevention and achieving good health. It is better to eat a diet with a variety than to concentrate on individual foods as the key to good health.

Recent developments on grapefruit from MNT news

Could grapefruit be good for your kidneys?

Scientists at Royal Holloway, University of London, have discovered that a natural product found in grapefruit can prevent kidney cysts from forming.

Could grapefruit juice curb the effects of a high-fat diet?

It is common knowledge that a diet high in fat can lead to weight gain. But could drinking grapefruit juice reduce this effect? A new study by researchers at the University of California-Berkeley claims it did for mice fed a high-fat diet, and it even lowered blood glucose levels and improved insulin tolerance.

Skin cancer risk linked with grapefruit and orange juice

A study published in June 2015 found people who consumed high amounts of whole grapefruit or orange juice were over a third more likely to develop melanoma, compared with those who consumed low amounts.