Grapefruit: Intolerance & Allergy

The grapefruit is the largest citrus fruit and brings it to a diameter of up to 30 centimeters. Its flesh is yellowish to pinkish or reddish and has a subtle, characteristic sweet and sour taste with a tart bitter undertone similar to grapefruit, which is a cross between grapefruit and orange. Grapefruit is a valuable citrus fruit because of its flavor and health-related phytochemicals such as minerals and trace elements, enzymes and a number of important vitamins, especially vitamin C.

Here’s what you should know about grapefruit.

The grapefruit is the largest citrus fruit, bringing it up to 30 centimeters in diameter. The grapefruit is an evergreen tree of the tropics, belonging to the rhombus family. The round, oval or almost pear-shaped fruit of the same name is the largest citrus fruit, with a diameter of up to 30 centimeters and a weight of up to 6 kilograms. Its thick skin (up to 1.5 cm) and the bitter taste of the separating membranes that divide the individual fruit segments are characteristic. Although the fruit is very similar to the grapefruit and is also often confused with it, it is an independent citrus fruit from which the grapefruit developed by crossing with an orange species. The origins of the grapefruit lie in the tropical regions of Southeast Asia. Due to its valuable constituents, it is now cultivated in many tropical to subtropical regions, even in the still frost-free areas of temperate zones. The main areas of cultivation for export are the USA, Brazil and Israel. Depending on the variety, the flesh is yellowish to pink or even red. Varieties with dark flesh are usually sweeter in taste than the light-fleshed grapefruits. The main harvesting season in the tropical and subtropical areas of the northern hemisphere is from December to June, with slight shifts forward or backward depending on weather conditions. Unlike the grapefruit, the grapefruit cannot simply be cut in half and spooned out of the peel because the separating skins are very bitter. However, the skin of the grapefruit separates more easily from the flesh and the individual fruit segments are more stable than those of the grapefruit, so the flesh can be easily detached and freed from the separating membranes. If grapefruits are offered outside the main harvesting season November to July, it is advisable to check their origin. It should then be a region south of the equator, where the main vegetation seasons are shifted by six months compared to those in the northern hemisphere.

Significance for health

Although the flesh of the grapefruit can taste very sweet, its nutritional value (caloric value) is actually slightly lower than that of the grapefruit, at about 46 kilocalories. The health value of the grapefruit is not based on its primary nutrient content, because except for 9 grams of sugar (carbohydrates) per 100 grams, proteins and fats are present only in traces. The health significance of grapefruit lies rather in its rich supply of secondary plant compounds with health relevance. Particularly noteworthy here is its extraordinarily high content of vitamin C and some other essential vitamins from the vitamin B complex, as well as vitamin E. In addition, grapefruits are valued as a supplier of metabolically relevant minerals – especially potassium – and trace elements. The special health significance here lies less in the metabolic effectiveness of individual substances than in the interaction of all the ingredients. They offer the body and its immune system help to help themselves, because the body can select from the substances that it just needs to be able to produce certain substances itself. The immune system then does not suffer from the fact that required basic substances are not present and possibly required defense reactions are therefore absent. A special health effect is caused by the decomposition product of the contained bitter substance naringenin. It leads to an inhibition of a certain enzyme in the liver, which, among other things, is responsible for the degradation of certain poisons and medicinal substances. In reality, the effectiveness of particular drugs such as statins (cholesterol-lowering drugs) and beta-blockers can then be greatly increased and altered. The effect of drugs can also be increased and their degradation delayed.

Ingredients and nutritional values

The nutritional value of the grapefruit is – as stated above – surprisingly low at 46 kilocalories. It is therefore not the fruit that provides the quick energy boost during vigorous physical activity or competitive sports. On the contrary, the bitter substances it contains stimulate the production of gastric juice and thus promote digestion. As a result, nutrients and energy (sugar) are supplied more quickly from the food, which in turn is associated with a faster onset of a feeling of satiety. The ingredients, which have nothing to do with the nutritional value, are therefore in the foreground with the grapefruit. Based on 100 grams of fruit flesh, these are vitamin C with 61 milligrams as well as several vitamins from the B complex, carotenoids as precursors for the formation of vitamin A and noteworthy concentrations of vitamin E (270 micrograms). In terms of minerals, grapefruit provides mainly potassium, calcium, magnesium and phosphorus.

Intolerances and allergies

In addition to the above-mentioned – sometimes dangerous – interactions of certain ingredients of grapefruit with many drugs, especially statins (lowering cholesterol), antihypertensives and beta-blockers to stabilize heart rhythm, in rare cases there are intolerance or allergic reactions due to the biogenic amines contained. These are histamines that play an important role in inflammatory reactions. In addition, grapefruits also provide so-called histamine liberators, which induce the immune system to release histamines.

Shopping and kitchen tips

As with the purchase of other citrus fruits, it is advisable to look for organic qualities in grapefruit to ensure that the fruit is not contaminated with pesticides and that the greatest possible variety of ingredients is available. Since there is often no distinction between grapefruit and pomelo, the appearance of the fruit should also match the characteristic features of the pomelo. Grapefruits are round to pear-shaped and flattened on the top and bottom. It is a post-ripening fruit, but it should not be stored in the refrigerator for preservation because it is sensitive to cold and quickly loses aroma and flavor at temperatures below 8 degrees. The fruit ripens best at room temperature and keeps fresh for about two weeks. The flesh is more stable than that of the grapefruit and the 10 to 15 fruit segments are easier to remove from the peel and free from the white, bitter-tasting, segment skins. When raw, grapefruit can contribute to the healthy enrichment of many dishes.

Preparation tips

Grapefruit can be very good for enriching an exotic fruit salad, but should not be mixed with other citrus fruits. Its sweet to slightly tart flavors develop best when combined with bananas, berries, apples, pears and grapes. Finely chopped walnuts also go very well with them. Alternatively, grapefruit juice can be used to flavor salad dressings and other dressings. Grapefruit juice can also have its flavoring effect in cocktails or fruit punch.