Foundation Diet and Health
Diet and Health
The best perspective for your health

Red or pink grapefruit

Grapefruit may cause serious interactions with certain medicines. Plase read the text below. The pectin and antioxidants in grapefruit benefit overall health

Pictogram nutrient tables

Like other citrus fruits, grapefruit contain antioxidants, free radical scavengers, and the fiber pectin. Eating grapefruit not only helps with weight loss but can also help prevent diabetes mellitus. Please note the drug interactions described below.

Culinary uses:

Grapefruit are a favorite breakfast fruit. Some people like to eat them with a little sugar sprinkled on top. They are also used in a variety of fruit salads and mixed drinks.

In Costa Rica, especially in Atenas, grapefruit are often cooked to remove their sourness, rendering them as sweets; they are also stuffed with dulce de leche, resulting in a dessert called toronja rellena (stuffed grapefruit). In Haiti, grapefruit is used primarily for its juice (jus de Chadèque), but also is used to make jam (confiture de Chadèque).1

Nutritional information:

Grapefruit are an excellent source of vitamin C as a 100 gram serving contains >20 % of the daily recommended value. They also contain the fiber pectin, which can improve digestion and relieve diarrhea and constipation. Pectin has also been suggested as a natural treatment for diabetes. In addition, red and pink grapefruit contain lycopene, a carotenoid phytonutrient, which has been shown to have anti-tumor activity. Among the common dietary carotenoids, lycopene has the highest ability to help fight oxygen free radicals, compounds that can cause damage to cells.

Studies have shown that grapefruit help lower cholesterol. Grapefruit juice is also rated among the juices with the highest antioxidant activity. The “grapefruit diet” is a popular diet based on the theory that the fruit’s low glycemic index can improve the body’s ability to burn fat.

Drug interactions:

Grapefruit and grapefruit juice have been found to interact with numerous drugs and in many cases, to result in adverse direct and/or side effects (if dosage is not carefully adjusted.) This happens in two very different ways. In the first, the effect is from bergamottin, a natural furanocoumarin in both grapefruit flesh and peel that inhibits the CYP3A4 enzyme, (among others from the P450 enzyme family responsible for metabolizing 90% of drugs). The action of the CYP3A4 enzyme itself is to metabolize many medications. If the drug's breakdown for removal is lessened, then the level of the drug in the blood may become too high or stay too long, leading to adverse effects. On the other hand, some drugs must be broken down to become active, and inhibiting CYP3A4 may lead to reduced drug effects.

The other effect is that grapefruit can block the absorption of drugs in the intestine. If the drug is not absorbed, then not enough of it is in the blood to have a therapeutic effect. Each affected drug has either a specific increase of effect or decrease. One whole grapefruit, or a glass of 200 mL (6.8 US fl oz) of grapefruit juice may cause drug overdose toxicity. Typically, drugs that are incompatible with grapefruit are so labeled on the container or package insert. People taking drugs should ask their health care provider or pharmacist questions about grapefruit and drug interactions.

General information:

From Wikipedia: The grapefruit (Citrus × paradisi) is a subtropical citrus tree known for its sour to semi-sweet, somewhat bitter fruit. Grapefruit is a hybrid originating in Barbados as an accidental cross between two introduced species, sweet orange (C. sinensis) and pomelo or shaddock (C. maxima), both of which were introduced from Asia in the seventeenth century. When found, it was named the "forbidden fruit"; and frequently, it has been misidentified with the pomelo. The grapefruit's name alludes to clusters of the fruit on the tree, which often appear similar to that of grapes.1


The most popular varieties are the white, pink, and red varieties.
The 1929 Ruby Red patent was associated with real commercial success, which came after the discovery of a red grapefruit growing on a pink variety. Using radiation to trigger mutations, new varieties were developed to retain the red tones which typically faded to pink. The Rio Red variety is the current (2007) Texas grapefruit with registered trademarks Rio Star and Ruby-Sweet, also sometimes promoted as "Reddest" and "Texas Choice". The Rio Red is a mutation bred variety that was developed by treatment of bud sticks with thermal neutrons. Its improved attributes of mutant variety are fruit and juice color, deeper red, and wide adaptation. The Star Ruby is the darkest of the red varieties. Developed from an irradiated Hudson grapefruit, it has found limited commercial success because it is more difficult to grow than other varieties. The varieties of Texas and Florida grapefruit include: Oro Blanco, Ruby Red, Pink, Rio Star, Thompson, White Marsh, Flame, Star Ruby, Duncan, and Pummelo HB.1

Literature / Sources:

  1. Wikipedia. Grapefruit [Internet]. Version dated October 31.