When a sweet orange crossed with pomelo in subtropical Barbados, the result was the grapefruit. The fruit tends to taste sour with slightly sweet and bitter undertones. You can find grapefruit in red, pink, white, and yellow varieties.
The grapefruit was originally referred to as the forbidden fruit. Is that because of all the amazing health benefits? Let’s dig deep into one of the largest citrus fruits to see just what it has to offer your overall health.
- 1 What is Grapefruit: History of the Grapefruit
- 2 Nutritional Breakdown of Grapefruit
- 3 Grapefruit Health Benefits: What Does the Research Say?
- 4 Grapefruit & Medications
- 5 Grapefruit Diets
- 6 Grapefruit Recipes
- 7 The Bottom Line on Grapefruit
- 8 Questions & Answers on Grapefruit
What is Grapefruit: History of the Grapefruit
The origins of the grapefruit, the sweet orange, and pomelo were brought over to the west from Asia in the late 1600s. Official documentation of the fruit was first made in 1750 by Griffith Hughes, the author of The Natural History of Barbados. There are more than 15 varieties of grapefruit, but the most popular and well-known is the Ruby Red.
Nutritional Breakdown of Grapefruit
According to the United States Department of Agriculture, grapefruit includes, per fruit:
- Calories: 129
- Protein: 2g
- Fat: 0.4g
- Carbohydrates: 33g
- Sugar: 21g
- Fiber: 5g
Grapefruit is also a fantastic source of potassium (416mg), vitamin C (96mg), beta carotene, and lycopene. We’ll look more closely at the impact of potassium and vitamin C now. We’ll then dig into the other elements in grapefruit like naringin, naringenin, and more, and their effect on health shortly.
Citrus fruits like grapefruit are part of the Noom meal plan. Noom teaches you how to choose the healthiest foods in just the right portion sizes to control appetite and lose weight for the last time.
Grapefruit Health Benefits: What Does the Research Say?
As you can see, grapefruit packs quite the nutritional punch, but it’s the potassium and vitamin C that stands out because of the high concentrations present. There are also some other elements to consider, including naringin and naringenin, which we’ll get to shortly. First, let’s uncover more about potassium and how it affects your health and then really dig into vitamin C.
Potassium & Your Health
The big push in research into potassium appears to be in the area of hypertension or high blood pressure, as that’s the topic of the majority of research we found on the electrolyte.
In 2015, a review of randomized trials, 15 in all, included people taking potassium supplements without taking medication for hypertension. More than 900 patients were participating. In patients with hypertension, who were not currently on medication, systolic blood pressure was reduced by 6.8 mmHg, and diastolic blood pressure was reduced by 4.6 mmHg, on average. At the conclusion of the research, authors found, “Potassium supplementation is associated with reduction of blood pressure in patients who are not on antihypertensive medication, and the effect is significant in hypertensive patients.”
In 2016, additional research shared that the link between potassium supplementation and reduced hypertension is clear, but the way that potassium works is still unclear. This leads to the need for additional, large-scale research.
In opposition to the article mentioned above, research in the Journal of Physiology and Biochemistry, also in 2016, claimed that the impact potassium has on blood pressure has been shown and replicated in various studies. The study mentions that blood pressure isn’t the only body process affected by potassium supplementation. “… the blood pressure lowering effects of potassium were presented in several intervention trials and summarized in a handful of meta-analyses. Furthermore, accumulating epidemiological evidence from, especially, the last decade relates low dietary potassium intake or serum potassium levels to an increased risk for insulin resistance or diabetes.”
When we looked more closely at the potential relationship between potassium and insulin and diabetes, we found that though authors haven’t found an increased risk of developing diabetes in patients with low potassium levels, they did find that low levels may be associated with an increased risk of insulin resistance.
Vitamin C & Your Health
The research into vitamin C’s impact on health is abundant. Since vitamin C is one of the most concentrated vitamins in grapefruit, we have to uncover all the potential benefits.
- Common Cold
Grapefruits can help beat the common cold, or can they?
Undoubtedly, at the top of the list is the role vitamin C plays in the common cold. Research into the common cold spans decades, and, as of yet, we’ve yet to discover a cure for the condition. However, we have realized how to minimize the common cold’s impact with natural supplements and health foods like vitamin-C-rich grapefruit.
In one 2012 study, patients who were given a combination of vitamin C and zinc spent less time with a runny nose than the control or placebo group. Results showed up to a 27% decrease in time spent with symptoms.
Now, the Cochrane Library, a well-respected journal that publishes large-scale reviews of research, found in January 2013 that “the failure of vitamin C supplementation to reduce the incidence of colds in the general population indicates that routine vitamin C supplementation is not justified.” More than 11,000 participants were included in the meta-analysis. These results fly in the face of the majority of other studies and reviews.
What’s funny about research is that the results can ebb and flow over time. When we jump forward to 2018, another research review comes to a very different conclusion than the Cochrane study. This time around, researchers found “extra doses of vitamin C could benefit some patients who contract the common cold despite taking daily vitamin C supplements.”
One of the newest studies we found was from 2019. The Korean military investigated the effect of vitamin C on soldier’s health and found it benefited them enough to suggest changes to “military healthcare policies that can provide vitamin C supplementation for military personnel in basic military training.”
Did you know how important vitamin C is to your overall health? Learn about its role and more with daily health lessons from Noom and find out how you can lose weight for good.
Will a grapefruit a day keep the doctor away?
If you want to know the effect vitamin C has on immune function, research can take it down to a cellular level. “… results provide strong experimental evidence supporting a role for ascorbic acid [vitamin C] in T-cell maturation as well as insight into the mechanism of ascorbate-mediated enhancement of immune function.” T-cells are immune cells.
“Vitamin C contributes to immune defense by supporting various cellular functions of both the innate and adaptive immune system.” It does this by promoting skin health, thus protecting against environmental stress. It also accumulates in neutrophils and other harmful cells and kills them. Then, vitamin C helps rid the body of the dead neutrophils. There’s also the fact that “vitamin C deficiency results in impaired immunity and higher susceptibility to infections.”
- Wound Healing
Something as simple as grapefruit can speed up the wound healing process?
Vitamin C is present in several phases of the wound healing process. When a wound is inflamed, it works to kill neutrophils and clear out the dead cells. It helps with the “synthesis, maturation, secretion and degradation of collagen.” Collagen plays a critical role in wound healing via scar formation and other aspects.
- Skin Health
So, eating grapefruit can make skin healthier?
Vitamin C has been described as a potent antioxidant, and that isn’t just talking about taking a supplement. The vitamin can be applied topically to the skin as a treatment for aging and hyperpigmentation. Early research suggested the biggest problem was with delivery because of vitamin C’s instability making it difficult to deliver the best dose.
Antioxidants like vitamin C are used by the body to maintain skin homeostasis or balance. It’s this balance that protects the skin from oxidative stress and damage.
We first found mention of instability in a 2013 study we reviewed. It appears that years later, that instability is still a problem to be addressed. According to a review of research in 2017, “Topical vitamin C has a wide range of clinical applications, from antiaging and antipigmentary to photoprotective. Currently, clinical studies on the efficacy of topical formulations of vitamin C remain limited, and the challenge lies in finding the most stable and permeable formulation in achieving the optimal results.”
- Bone Health
How does vitamin C in grapefruit impact bone health?
Vitamin D may be the star in bone health, but bones would be brittle, and collagen levels would suffer without vitamin C. Research shows vitamin C has “been correlated with increased bone mineral density and improved bone strength when provided in physiological amounts.” The study goes on to say, “Vitamin C is essential for the formation of collagen and for fracture healing.”
According to the Journal of Bone and Mineral Research, “Overall, vitamin C exerts a positive effect on trabecular bone formation by influencing expression of bone matrix genes in osteoblasts.”
- Brain and Cognitive Health
What possible role could grapefruit, or in this case, the vitamin C supplied by grapefruit, have on brain and cognitive health?
Research as early as 2014 shared that “Increasing evidence is pointing to vitamin C (VitC) as an important redox homeostatic factor in the central nervous system, linking an inadequate dietary supply of VitC to negative effects on cognitive performance.” As of that time between 10 and 15% of the world’s population was insufficient or deficient in vitamin C. A number which has grown significantly since then. “… it also plays a role in the learning and memory process as well as in the structure and support of the nervous system.”
In a 2017 review of research that included 50 previously completed studies on healthy and cognitively-impaired participants, vitamin C status was significantly different between them. Simply put, “studies demonstrated higher mean vitamin C concentrations in the cognitively intact groups of participants compared to cognitively impaired groups.”
There’s also evidence that vitamin C may impact mood. According to a study on 139 males in New Zealand, low vitamin C status correlated with depression, anger, and confusion. Authors suggested that “high vitamin C status may be associated with improved overall mood.”
While not directly naming Covid-19, recent research suggests that vitamin C supplementation, when taken at mechanical ventilation, reduces the time on a ventilator with increased effects the more time a patient spends on breathing assistance. The result was clinically significant, starting at 10 hours of ventilation. Shorter ventilation times didn’t benefit from vitamin C supplementation. In some instances, ventilation times were reduced up to 31%.
Researchers are also suggesting that a combination of vitamin C and quercetin can be used as a prophylactic to protect against Covid-19.
The latest research, published in November/December 2020 in Nutrition, shares some fantastic highlights of how vitamin C can protect against and fight Covid-19 infection.
- “Severe acute respiratory syndrome coronavirus 2 causes a respiratory infection, at times followed by severe systemic illness.
- Low dose (0.5–2 g/d) vitamin C may have benefits when used early in severe acute respiratory syndrome coronavirus 2 infections.
- Severe late forms of coronavirus disease 2019 are due to a cytokine storm involving interleukin-6 and endothelin-1.
- Vitamin C (especially at high doses) can reduce mediators such as interleukin-6 and endothelin-1.
- Thus, vitamin C may also benefit patients with severe late-stage coronavirus disease 2019.”
What is Naringin?
Naringin is a “major flavanone glycoside obtained from tomatoes, grapefruits, and many other citrus fruits.” Research has shown it may possess antioxidant and anti-inflammatory properties. To be more specific, there’s evidence that naringin impacts “atherosclerosis, cardiovascular disorders, diabetes mellitus, neurodegenerative disorders, osteoporosis, and rheumatological disorders.”
Further research shows, “NAR [naringin] is endowed with broad biological effects that could improve human health. Since a scarce number of clinical studies have been performed, their use requires more investigation in order to know better their safety, efficacy, delivery, and bioavailability in humans.”
How Does the Body Benefit From Naringin?
The majority of the clinical research on Naringin’s impact on obesity has been completed on rat models. With that said, results indicate a reduction in fat tissue with naringenin supplementation lasting six weeks. Researchers suggest various methodologies, including anti-inflammatory and protein uncoupling actions as a means of promoting fat loss.
In another study published in PLOS One, rats given clarified grapefruit juice showed reductions in weight after diet-induced obesity. Again, this is an animal study that can’t be directly related to humans. Still, the potential is there, leading to further research and validation for using grapefruit for weight loss.
When looking for research using humans, we were able to find a 2006 study that showed significantly more weight loss in participants who consumed a half grapefruit, grapefruit juice, or a grapefruit supplement before meals. The effect was more significant in people with metabolic syndrome.
Are you getting enough naringin? Learn how to choose the best foods for a well-balanced diet and more with the Noom program. Noom offers a fresh take on weight loss by using psychology and daily lessons to keep you on track to success.
The same issue with available human studies can be said for investigations into Naringin’s effect on osteoporosis. Based on available rat studies, Naringin reverses a specific type of osteoporosis-related to the removal of ovaries. Essentially, this could impact women over 50 who’re in menopause. At least 20% of women over 50 are affected by osteoporosis.
“Cervical cancer is the second most common female cancer worldwide.” Studies reveal that “Naringin showed a 50% inhibition of… human cervical cancer cells.” This leads researchers to believe that the chemical may be a viable treatment for cervical cancer in humans.
There’s also evidence that Naringin may work against triple-negative breast cancer cells. Triple-negative breast cancer is of particular concern because it is an aggressive type of cancer with few targeted therapies. Study authors “suggest Naringin might be used as a potential supplement for the prevention and treatment of breast cancer.”
It is estimated that more than 30 million people across the world are currently managing neurological illnesses. “Naringin has been shown to possess outstanding therapeutic potential as a neuroprotective agent.” If this is accurate, the polyphenol could show promise in the prevention, or slowing, of neurodegeneration associated with neurological conditions.
Research has also shown “evidences suggest that naringin may be a potential natural compound involved in the prevention and treatment against neurodegenerative diseases.”
What is Naringenin?
Naringenin is a flavonoid found in naringin. “Several biological activities have been ascribed to this phytochemical, among them antioxidant, antitumor, antiviral, antibacterial, anti-inflammatory, antiadipogenic and cardioprotective effects.” It’s also “demonstrated therapeutic potentials… in the treatment of several inflammation-related disorders, such as sepsis, fulminant hepatitis, fibrosis, and cancer.”
“Naringenin is used for the treatments of osteoporosis, cancer, and cardiovascular diseases, and showed lipid-lowering and insulin-like properties.” It also works as a chemopreventive and to fight liver diseases.
What are Furocoumarins?
Furocoumarins are “natural plant constituents” found in grapefruit juice. When researchers investigated commercially prepared juice and compared the furocoumarin levels to fresh juice, three major types of constituents were found – bergaptol, bergamottin, and 6’, 7’ -dihydroxy-bergamottin (DHB).
Concentrations of these constituents differed between the two types of juice. Commercially prepared juice contained the most bergaptol, while fresh juice contained the most DHB. Bergamottin was the midline constituent in both cases.
We also know that the body converts these constituents into bergaptol. In cases where study participants were given juice containing all three, more bergaptol was excreted in urine than was taken in via supplementation.
“In the past few years, grapefruit furanocoumarins have been demonstrated to exhibit several biological activities including antioxidative, -inflammatory, and -cancer activities as well as bone health promotion both in vitro and in vivo.”
What is Bergamottin?
Bergamottin is a furocoumarin that’s been shown to have anti-cancer properties in both in-vivo and in-vitro studies. Effects like this are critical to the treatment of cancer because despite “significant advances in treatment options and the advent of novel targeted therapies, there still remains an unmet need for the identification of novel pharmacological agents for cancer therapy.”
Grapefruit & Medications
The enzyme CYP3A4 is critical to the metabolization of certain medications. Grapefruit inhibits or blocks this enzyme, which leaves less of the drug metabolized and more to enter the bloodstream. While this may sound like a good thing, when more of a drug enters the bloodstream, and in some cases, stays in the bloodstream longer, it can affect the effectiveness and efficiency of medications.
While not all medications are altered by grapefruit, plenty are. The affected medications may include:
- “Some statin drugs to lower cholesterol, such as Zocor (simvastatin) and Lipitor (atorvastatin).
- Some drugs that treat high blood pressure, such as Procardia and Adalat CC (both nifedipine).
- Some organ-transplant rejection drugs, such as Sandimmune and Neoral (both cyclosporine).
- Some anti-anxiety drugs, such as buspirone.
- Some corticosteroids treat Crohn’s disease or ulcerative colitis, such as Entocort EC and Uceris (both budesonide).
- Some drugs that treat abnormal heart rhythms, such as Pacerone and Nexterone (both amiodarone).”
There’s also the potential for interaction with some over-the-counter medications, as well, so before adding grapefruit or grapefruit juice to your diet, if you’re taking medications of any kind, seek the advice of your healthcare or prescribing provider.
The Standard Grapefruit or Grapefruit Juice Diet
The grapefruit diet is one of the oldest trends out there, with roots back to the 1930s. It’s been around the world and back again, and it’s still going strong. The plan has evolved over the years, and several varieties have branched off the original set of instructions. What most stress is the need to consume ½ a grapefruit or 8 ounces of grapefruit juice with each meal.
The majority of grapefruit diets are lower-carb, lower-calorie, and higher-protein. Calorie intake ranges widely, with some diets suggesting as few as 800 calories a day. You follow the diet between 8 and 14 days.
The Military Diet
The military diet is a popular three day on, four day off plan that offers a set menu for the first three days of the week and a more flexible menu for the remainder of the time. During the first three days, grapefruit is an “allowed” food that offers plenty of nutrition and few calories.
Though there have been claims that the military introduced the military diet to help soldiers lose weight quickly, there’s been no real connection to any branch of the military. Reviews of the diet suggest all weight loss is attributed to maintaining a low-calorie intake of between 1100 and 1400 on days one to three and keeping calories under 1500 for all other days.
The 3-Day (7-Day) Grapefruit Diet
The 3-day and 7-day grapefruit diets are a stricter version of the original plan promoting extreme calorie restriction. For the duration, grapefruits are free foods that you can eat anytime you feel hungry. They are also incorporated into the menu, so you’ll eat a minimum of two grapefruits daily. You can expect to eat fewer than 1000 calories per day. Some meal suggestions include:
Breakfast: one whole grapefruit paired with one slice of toast, a cup of blueberries, or oatmeal.
Lunch: half a grapefruit paired with tomato soup, grilled tofu, grilled chicken, or other low-calorie protein.
Dinner: half a grapefruit paired with a cup of yogurt, broccoli, almond milk, or cottage cheese.
Snacks: steamed vegetables, canned tuna, or grapefruit.
The 14-Day Egg & Grapefruit Diet
From all accounts we could find, the 14-Day Egg and Grapefruit Diet is as close to a starvation diet as you can get. Quite a few suggested meals look something like this:
Breakfast: one grapefruit and two hard-boiled eggs
Lunch: one whole fruit
Dinner: two hard-boiled eggs
The total calories for the day, if the whole fruit at lunch were a large apple, top out at 456. That’s less than 500 calories, which is not a healthy choice for weight loss on any account. Not only that, but the nutrition breakdown for a diet like that is in no way balanced.
Total Fat: 19.8g
Cholesterol: 744mg (248%)
Total Carbohydrate: 45.4g
Dietary Fiber: 7.4g
Total Sugars: 34.1g
Vitamin D: 164mcg (820%)
Calcium: 116mg (9%)
Iron: 5mg (26%)
Potassium: 681mg (14%)
As you can see, the nutritional values are all over the place. The diet supplies far too much cholesterol and nowhere near enough calcium, potassium, iron, protein, fat, fiber, or many other micronutrients.
The Mayo Clinic Grapefruit Diet
The Mayo Clinic Grapefruit Diet isn’t associated with the Mayo Clinic medical center in any way. Somehow the name of the clinic got stuck with this lower-carb, lower-fat diet that plays to the supposed fat-burning benefits of grapefruit.
This is one of the stricter diets. You have two options for each meal each day. You can feel free to choose one or the other, but it is suggested that you alternate between the two.
Breakfast: You will eat half a grapefruit or drink eight ounces of grapefruit juice with two eggs each morning. You can alternate between two slices of bacon or sugar-free coffee or tea with a slice of toast.
Lunch: Again, you will eat half a grapefruit or drink eight ounces of juice with lunch. You’ll alternate between eating as many tomatoes as you’d like and having a salad with a dressing of your choice. You also get to add either unlimited meat or sugar-free coffee or tea.
Dinner: There are two utterly different dinner options, so you’ll only have to eat grapefruit some nights. Your two dinner options are:
- half a grapefruit (or eight ounces of juice), unlimited meat, a salad with dressing, and sugar-free coffee or tea
- two eggs, one slice of toast, as much celery, lettuce, cucumber as you’d like, and sugar-free coffee or tea.
All fruits, including grapefruit are allowed on the Noom program. That’s because all foods are permitted on Noom. Noom doesn’t prohibit foods, eliminate food groups, or restrict the user like many fad diets. You can lose weight eating the foods you love and keep it off.
So, what’s the tastiest way to get more grapefruit in your diet? Let’s look at a few grapefruit recipes that shine a light on this vitamin-packed citrus fruit.
A refreshing combination of herbs and fruit that can easily be used to top a ton of tasty dishes.
2 cups grapefruit, chopped
1 jalapeno, diced
2 shallots, diced
2 to 3 basil leaves, ribboned
1 teaspoon thyme
juice of 1 grapefruit
Combine all ingredients in a bowl, toss and allow to marinate for at least four hours. Serve over fish, chicken, vegetables, salad, and more.
This recipe utilizes the grapefruit peel instead of the fruit.
2 cups granulated sugar
Remove the peel from the grapefruits, leaving about ¼” of the white skin (pith) attached to the skins. Add to a small pot and cover with water. Bring the grapefruit peels to a boil and drain. Repeat this process two more times to prepare the peels to be candied.
Next, add peel, 1 cup granulated sugar, and ½ cup water to a small pot and bring to a boil. Lower heat and simmer for at least 15 minutes, but likely closer to 20 or 25 minutes or until the peels are translucent. After draining, allow the peels to cool and dry for at least four hours. Finally, toss the peels in the remaining 1 cup granulated sugar and enjoy.
This fantastic yet straightforward grapefruit dish is ideal for a refreshing start to your day.
2 large grapefruit, cut in half
4 tablespoons sugar
After cutting grapefruit in half, take a small bit off each section’s bottom to ensure the fruit is balanced on the baking sheet. After preheating the broiler, place the grapefruit pulp side up under the broiler for 2 to 3 minutes until the fruit is dry. Remove the baking sheet from the broiler carefully, and sprinkle 1 tablespoon of sugar on the top of each grapefruit half. Return to the broiler for 6 to 8 minutes, or until the sugar is a deep golden brown. Allow the fruit to cool before serving.
The Bottom Line on Grapefruit
Grapefruit is an extremely versatile citrus fruit. It can be consumed to help weight loss, reduce lipids, decrease cancer risk, and decrease stroke risk. Like all foods, it should be eaten in moderation. However, for people taking statins or other prescription drugs, grapefruit should be avoided.
For most of us, grapefruit is a safe part of a healthy, balanced diet. If you need to avoid it, Noom can help you learn more about the best food choices for your overall health.
Questions & Answers on Grapefruit
What are the benefits of eating grapefruit?
Based on clinical research, grapefruit is packed with vitamins and antioxidants, which may support heart health, immune function, weight loss, and blood glucose control.
Why is grapefruit bad for you?
Grapefruit is not bad for you. In some cases, eating grapefruit while taking prescription or over-the-counter medications can cause issues with the medication level in the bloodstream. Anyone taking medications should consult with the prescribing healthcare provider before eating or drinking grapefruit regularly. The effects on drug levels are compounding, which means as you consume more grapefruit, the impact on drug levels is affected more strongly.
Who should not eat grapefruit?
Anyone taking prescription medications or some over-the-counter medications should not eat grapefruit without seeking a healthcare professional’s advice. Grapefruit inhibits and blocks an enzyme required for the metabolism of some drugs and medicines.
Does grapefruit burn belly fat?
No, grapefruit doesn’t burn belly fat. There are no foods that specifically burn fat in any particular area.
Is it OK to drink grapefruit juice every day?
Yes, it is OK for some people to drink grapefruit juice daily. The juice is packed with excellent nutrients, vitamins, and antioxidants. However, if you’re taking any medications, talk with the prescriber before drinking grapefruit juice due to potential drug interactions.
Is grapefruit a blood thinner?
Grapefruit is not a blood thinner, but it does negatively interact with blood-thinning medications. In some cases, grapefruit increases the risk of bleeding, and in others, a reduced effect on blood clots’ prevention.
What are the side effects of eating grapefruit?
There is some indication that grapefruit can increase the risk of certain cancers and type 2 diabetes in women.
Why should people with diabetes not eat grapefruit?
There are a couple of reasons why people with diabetes should avoid grapefruit. First, some research shows that women who consume grapefruit regularly are at increased risk of developing type 2 diabetes. Also, grapefruit can interact with metformin, a popular diabetes drug.
Does grapefruit make you poop?
There’s no indication that eating grapefruit or drinking grapefruit juice will make you poop. However, if you’re taking prescription or over-the-counter medications that can cause increased bowel movements, and grapefruit interacts with those drugs, this could cause an issue.
Is grapefruit better than orange?
Grapefruit is not better than orange. The two are both healthy citrus fruits with plenty of vitamins and nutrients. Grapefruit is a cross-breed between orange and pomelo.