Grapefruit is rich in vitamin C, helps to lose weight, protects against cardiovascular diseases, and has many other positive health properties. For breakfast, dessert, or in juices and salads – their sweet and sour taste ensures a fresh aroma.
White and red grapefruits
The grapefruit (Citrus paradisi) is the fruit of the grapefruit tree that grows in subtropical countries. Like oranges, tangerines, and clementines, it belongs to the rue family. The sweet and sour citrus fruit comes in two varieties: the white grapefruit, whose flesh is light yellow, and the red grapefruit, whose flesh is pink to red.
In German, the fruit is called grapefruit, although the English name is now almost more common. The grapefruit got its name because the fruits, like grapes, grow close together on the tree. Other names are Adam’s apple or paradise apple, which the Latin name Citrus paradisi indicates.
The difference between pomelo, grapefruit, and pomelo
Colloquially, the grapefruit is also called pomelo. Contrary to popular belief, a pomelo is not the same as a grapefruit. The grapefruit is instead a hybrid of the pomelo (Citrus maxima) and orange. While the grapefruit is round with a light yellow-orange skin, pomelos are more pear-shaped or flat-topped with yellow-green skin.
Also to be distinguished from the grapefruit is the pomelo – a cross between grapefruit and grapefruit. However, the pomelo is not a separate species but is counted among the grapefruits. It has yellow to pink flesh and green-yellow skin, so it looks more like a pomelo than a grapefruit. The name is also a bit confusing since pomelo means pomelo in English and grapefruit in French.
It is believed that the grapefruit was first discovered in Barbados in 1750. She later came to Florida, where California and Texas are still the main plantations in the USA. The grapefruit is now grown in almost all subtropical areas of the world.
Table: nutritional values, vitamins, and minerals
Fresh grapefruit consists of around 86% water and is very low in calories (50 kcal per 100 g). They are particularly rich in vitamin C. For orientation: A grapefruit weighs about 270 g on average.
Grapefruit and lycopene
Lycopene is a phytochemical that gives fruits and vegetables their red color, such as tomatoes, watermelon, and red grapefruit. Red grapefruits contain approx. 3.4 mg lycopene per 100 g. For comparison: Tomatoes contain between 0.9 and 4.2 mg lycopene per 100 g. Lycopene is one of the carotenoids. It has antioxidant, anti-cancer, and preventive effects on cardiovascular diseases.
Lycopene is particularly well known in connection with prostate cancer. However, the scientific community is divided on how and whether lycopene can help with prostate cancer, as there are contrary results in this regard. Based on a review from 2016, Chinese scientists explained that the study results differed so often because the studies were structured so differently that they could not be compared with each other.
For example, research from Asia and Oceania showed that lycopene protects against prostate cancer, while studies from other regions of the world have not found this to be the case. The risk of prostate cancer is higher in western countries than in Asian countries, which could also play a role.
In a new study from 2020, American researchers examined the data of around 28,000 men. Questionnaires revealed how often the men consumed tomato products – because the tomato is considered one of the foods richest in lycopene.
It was found that the consumption of cooked tomato products such as B. tomato sauce can reduce the risk of prostate cancer. When lycopene is heated, its bioavailability increases, which is why processed tomato products are more effective in terms of lycopene. However, a previous test-tube study showed that raw red grapefruit also contained relevant amounts of lycopene to inhibit the growth of prostate cancer tumors.
Lose weight with grapefruit
Traditionally, apples of paradise have long been said to help with weight loss, which is why numerous grapefruit diets are offered on the Internet. What is the truth of the claim that grapefruit is a “fat burner”?
Mexican scientists have summarized the research results on the influence of plant-based foods on weight in a review. The grapefruit was also examined:
Several studies on rats and one on humans have confirmed that consuming grapefruit helps with obesity and also lowers cholesterol levels, thereby reducing risk factors for cardiovascular disease.
In one of the studies, eating half a grapefruit before each meal for 3 months resulted in a weight loss of 1.6 kg in overweight people.
How exactly eating grapefruit leads to weight loss is not yet clear.
Of course, it’s possible that eating a grapefruit before each meal simply fills you up, which in turn reduces your calorie intake.
However, one study also described the possibility that grapefruit has a positive effect on fat metabolism (lipid metabolism) by breaking down fatty acids. However, there has not yet been sufficient research into which substances in grapefruit could make this possible. Secondary plant substances such as B. lycopene, naringin, or furocoumarins (more on that later) may be involved.
Another theory is that fiber pectin is at least partially responsible for the positive impact on weight by reducing appetite, speeding up digestion, and stimulating gastric juices. Pectin is also found in other fruits, with citrus fruits having a comparatively high pectin content – especially in the peel and to a lesser extent in the skins and pulp. The pectin content in the peel of citrus fruits is around 34%, and in the pulp of grapefruit, it is around 3.14% (for comparison: in apples, it is between 0.14 and 0.96%).
Grapefruit lowers blood sugar levels
In addition to its positive effect on weight, grapefruit also naturally lowers blood sugar levels. Naringin is said to be responsible for this. Naringin is a flavonoid, a phytochemical also found in grapefruit and pomelos. The bitter substance also gives these fruits their bitter taste.
Grapefruit for diabetes
In the study mentioned above, it was found that eating half a grapefruit before each meal helps with obesity and lowers blood sugar levels, causing less insulin to be produced. The participants’ insulin levels dropped within two hours after the meal. Grapefruit is therefore considered a fruit that can reduce the risk of diabetes. But grapefruit can also be wonderfully integrated into the diet if you have diabetes.
However, there may be a difference between grapefruit and diabetes medicines such as B. the active substance metformin, which can lead to interactions (further information below in the paragraph “Interactions between grapefruit and medication”). So if you are already taking medication, grapefruit as a part of your daily diet rich in vital substances is often no longer an option.
Grapefruit could be used for various diseases
Researchers assume that, among other things, the naringin contained in grapefruit is responsible for the many positive properties of health. In addition to the health benefits mentioned above, tests in the test tube have shown anti-inflammatory and anti-cancer effects.
Researchers also found that grapefruit may help with oxidative stress, bone regeneration, and central nervous system disorders such as Alzheimer’s and epilepsy.
The research results so far are very promising – unfortunately, there are no studies that have been carried out on the human organism.
The effects of grapefruit seed extract
Grapefruit seed extract — made from the crushed seeds and skin of the grapefruit — is also attracting scientific interest. Various studies have shown that grapefruit seed extract is an effective remedy against viruses, bacteria, and fungi.
Grapefruit seed extract can be applied externally or taken diluted with water. With flu and colds, for example, you can slowly increase the dose from 1 to 3 drops per day to a dose of 3 to 15 drops taken three times a day.
Interactions between the grapefruit and medication
There are repeated warnings about grapefruits and grapefruit juice because they can interact with some medications, such as birth control pills, cholesterol-lowering drugs (statins such as lovastatin), and antihypertensive drugs or heart medication (calcium channel blockers such as amlodipine).
The interaction varies from drug to drug: Grapefruit can increase or decrease the effect, increase the risk of side effects and even enhance some drugs so enormously that they become toxic. If the effect is weakened, the desired effect of the drug is not achieved, which can lead to a flare-up of the respective symptoms.
The furocoumarins, phytochemicals that inhibit a certain enzyme in the body, which in turn breaks down active ingredients in the body, are to blame for this. This breakdown function is included in the dosage – if the enzyme is now inhibited, it can no longer break down the medication as usual, which can now lead to an overdose.
Interactions with grapefruit in at least 85 drugs
In a review, Canadian researchers identified a total of 85 drugs that regularly interact with grapefruit. The findings were published in the Canadian Medical Association Journal in 2013. These include antidepressants, blood thinners, and cancer drugs.
So if you are taking any of these medications, check the package leaflet for information on interactions with grapefruit or ask your doctor or pharmacist, if in doubt, do not consume grapefruit.
Grapefruit juice and multivitamin juices containing grapefruit.
The interactions are also influenced by the consumed amount of grapefruit or grapefruit juice. With some drugs, one grapefruit was sufficient, with others, interactions only occurred through regular consumption of grapefruit or grapefruit juice. For example, with felodipine, an antihypertensive drug, eating a single grapefruit resulted in a 3-fold higher concentration of the drug in the blood, which can then cause hypotension.
Grapefruit during pregnancy and lactation
If you are not taking any medications during pregnancy, grapefruit and grapefruit juice are safe. If you are taking medication, you should read the package leaflet and check with your doctor.
This question is somewhat more difficult in relation to breastfeeding. We read again and again that mothers should not eat citrus fruits while breastfeeding, as too much acid in the baby’s stool could lead to sore buttocks. However, there is no scientific evidence for this, and not every baby reacts in the same way to different foods.
If you’re worried, you could try not to eat large amounts of citrus fruits when you first start breastfeeding and see how your baby reacts. However, it does not make sense to completely avoid citrus fruits right from the start, since babies can also get a sore bottom because of the diaper brand, skin care products, or other reasons.
In addition, your baby knows your eating habits from the long period of pregnancy, so it might miss the regular consumption of citrus fruits if you suddenly stopped eating them after birth.
Grapefruit for gout
Anyone suffering from gout will find information online that gout patients should do without grapefruit – often without justification.
With gout, too much uric acid builds up in the blood, which can lead to the formation of tiny uric acid crystals, which are then deposited in the joints, causing pain. Uric acid is formed when the body breaks down so-called purines, which is why low-purine foods are recommended for gout. However, 100g of grapefruit contains just 5mg of purines, while 100g of chicken wings contain 53mg of purines. So it can’t be that you don’t treat gout patients with grapefruit.
Presumably, people warn against grapefruit in gout because it is assumed that gout patients always take medication, e.g. B. the gout drug colchicine. However, the effect of colchicine is increased by the grapefruit, which could be dangerous, since colchicine is already considered to have many side effects.
It is best to try to treat gout with holistic measures so that you can do without medication in the future. Because then you can enjoy grapefruit again as you wish. With the right diet, for example, it is possible to lower uric acid levels naturally.
How to freeze grapefruit
You can also freeze grapefruit, although fresh grapefruit tastes much better and has a longer shelf life without freezing (see “How to store grapefruit” above). In addition, the consistency can change during freezing.
If you still want to freeze the apples of paradise, there are different options: either you press the grapefruit and freeze only the juice, or you cut the fruit into slices, put them in a small container or a freezer bag, and freeze them that way.
You can also freeze the whole fruit in one piece. To do this, wash them thoroughly, pat them dry, place them in a freezer bag and squeeze out the air. It can then be stored in the freezer for several months.
Or maybe you’d rather grow your own grapefruits and harvest them fresh instead?
A grapefruit tree as a container plant
Planting an orange tree in a bucket on the balcony is not uncommon in our latitudes. You can also maintain a grapefruit tree in a bucket. The decisive factor in whether you can also harvest the fruit is the location: It should be sunny and warm (preferably over 20 degrees).
The grapefruit tree is best placed in a conservatory or greenhouse. Because he can also stay there for the winter. If your grapefruit tree is on the balcony, on the other hand, you have to look for suitable winter quarters for it so that you can enjoy it next year, because it does not tolerate frost. Ideally, it overwinters indoors in a bright, unheated spot at 5 to 10 degrees.