Grapefruit

Synonym(s): citrus paradisi , grapefruit seed, Hesperidine, naringin

Nutrient group: plant extracts & active ingredients

Sources and physiological effects

Dietary sources
The grapefruit grows on a subtropical tree belonging to the rhombus family (Rutaceae). It likely originated in Barbados around 1750 from a spontaneous crossing between the pomelo and the orange. Nowadays it is cultivated in almost all subtropical countries. For some years now, grapefruit seeds have been used for the production of extracts characterized by a high content of secondary plant substances and polyphenols.
Physiological effects
Mucosa	Cytoprotective effects on mucosa cells by NO-mediated increase of microcirculation
Antioxidant	Protection of cells against oxidative damage
Antibacterial and antifungal	Antibacterial and antifungal effects due to disturbance of membrane functions of microorganisms

Detailed information

Antimicrobial effect of grapefruit

The effectiveness of the polyphenols and flavonoids of grapefruit seed extract has been proven against 800 different bacteria, viruses and fungi. These active substances destroy the bacterial membranes and thus promote cytoplasm leakage (1).

Protective effect of grapefruit on gastric mucosa

In the treatment of gastritis and ulcer diseases, there is a growing tendency to strengthen the gastric mucosa and thus buffer the irritant effect of gastric acids. Plant substances are used to contribute to cytoprotection of the mucosa, improve microcirculation in the gastric mucosa and accelerate cell renewal, especially in the ulcer development phase (2). Grapefruit seed extract plays an important role in this indication framework. Extract is produced from the seeds and flesh of Citrus paradisi (grapefruit) in a patented process. The polyphenols contained are converted into a stable quaternary compound. These bioactive plant substances (phenols, flavonoids) have antioxidant properties and have a particularly strong cytoprotective effect on the mucosa cells of the gastric mucosa. This is probably caused by an improved effect of the neurotransmitter NO and an increased microcirculation in the tissue (3). The latter appears to be caused by an improvement in the formation of certain neuropeptides by plant flavonoids (4). Flavones naringin and hesperidin have also been identified as active ingredients (5). The antibacterial and antifungal properties of grapefruit seed extract have also been proven in studies. The extract is effective against more than 800 bacteria and virus groups, 100 fungal species and a large number of single-cell and multicell parasites (1). The active principle seems to be the breaking open of the bacterial membranes by certain substances of the grapefruit seed extract within 15 minutes (1). The effectiveness against yeasts has also been demonstrated (5).

Grapefruit for the urogenital tract and intestinal mucosa

There are promising indications for the use of grapefruit seed extract in bladder and urinary tract infections. Again, the antibacterial properties of the plant source seem to be the same as those of the chemical source (6). The microflora of the intestine and overall gastrointestinal health are likely to be positively affected.

Indications

Effect	Indication	Dosage
Physiological effects at a low intake	For strengthening the gastric mucosa in gastrointestinal tract complaints, gastritis and irritable stomach	200 – 500 mg/d
	Complementary therapy for bacterial, fungal or parasitic infestation	500 – 1000 mg/d
	Complementary therapy for bladder and urinary tract infections	500 – 1000 mg/d

Administration

General income mode
When	Grapefruit seed extract should be taken before meals. Notes: Grapefruit seed extract interferes with cytochrome P450 and thus, among other things, the phase 1 detoxification of many drugs.
Side effects
No side effects are known to date.
Contraindications
Due to the influence on liver metabolism, grapefruit seed extract should be avoided when taking medication at the same time.

References

1) Heggers, J. P. et al. 2002. The effectiveness of processed grapefruit- seed extract as an antibacterial agent. J Altern Complement Med. 8(3):333-40

2) Wagner, H., Wiesenauer, M. 2003. Phytotherapie. Phytopharmaka und pflanzliche Homöopathika.

3) Zayachkivska, O. S. et al. 2004. Influence of plantoriginated gastroprotective and antiulcer substances on gastric mucosal repair. Fiziol ZH. 50(6):118-27

4) Zayachkivska, O.S. et al. 2005. Gastroprotective effects of flavonoides in plant extracts. J Physiol Pharmacol. 56 Suppl 1:219-31

5) Cvetnic, Z., Vladimir-Knezevic, S. 2004. Antimicrobal activity of grapefruit seed and pulp ethanol extract. Acta Pharm. 54(3):243-50

6) Oyelami, O. A. et al. 2005. The effectiveness of grapefruit seeds in treating urinary tract infections. J Altern Complement Med. 11(2):369-71

References Interactions:
Stargrove, M. B. et al. Herb, Nutrient and Drug Interactions: Clinical Implications and Therapeutic Strategies, 1. Auflage. St. Louis, Missouri: Elsevier Health Sciences, 2008.

Gröber, U. Mikronährstoffe: Metabolic Tuning –Prävention –Therapie, 3. Auflage. Stuttgart: WVG Wissenschaftliche Verlagsgesellschaft Stuttgart, 2011.

Gröber, U. Arzneimittel und Mikronährstoffe: Medikationsorientierte Supplementierung, 3. aktualisierte und erweiterte Auflage. Stuttgart: WVG Wissenschaftliche Verlagsgesellschaft Stuttgart, 2014.