Grapefruit (also called pomelo) is a citrus tree native to the West Indies and naturalized in tropical regions throughout the world. Growing to approximately six meters in height, grapefruit trees have dense, dark green foliage and large white flowers, which eventually produce a round yellow fruit. The interior of the fruit is divided into individual sections filled with juicy pulp (which may vary in color from light yellow to pink or red) and several white, ovate seeds.
Believed to have originated in Jamaica, grapefruit was well established throughout the West Indies by the time it was discovered by Europeans in the 17th century. While the fruit has been a popular food for centuries, in the last two decades, extracts from grapefruit seeds have also gained popularity for their purported health supporting value.
Synthesized from the pulp and seeds of grapefruit, grapefruit seed extract is known chemically as diphenol hydroxybenzene complex. Extracts sold commercially are usually composed of 60 percent extract combined with 40 percent vegetable glycerine to reduce bitterness and decrease the likelihood of irritation to the skin or mucous membranes.
Recommended dosages for grapefruit seed extract vary with the potency of different preparations. A common recommendation is 500 mg of 4:1 extract, twice daily. It appears to be safe at this dosage level. Some individuals find the extract's acidity too difficult to tolerate. Reported side effects include stomach upset and skin irritation.