The findings may surprise many consumers as the citrus fruit is often associated with acidity and irritation of the gastrointestinal tract. But the seed extract actually possesses antibacterial and antioxidative properties that calm the gastric tract, said the researchers at the recent Digestive Disease Week conference in Chicago.
The team from Jagiellonian University Medical College in Poland examined the effects of different doses of the extract (2-20 mg/kg) on induced gastric ulcers in rats.
They measured levels of gastric secretion, one the major causes of gastric ulcers, and also tested ulcer healing by using a combination of acetic acid (an acid compound used to induce experimental ulcers) with or without a COX-1 inhibitor (indomethacin, 2 mg/kg) and a COX-2 inhibitor (rofecoxib, 10 mg/kg).
Rats treated with the grapefruit extract at 10 mg/kg experienced a 50 per cent reduction in gastric acid secretion, and a progressive decrease in the area of gastric ulcers by days six and nine of treatment.
The treatment also prompted a significant rise in blood flow at the ulcer sites, which could also help healing.
But the effects were completely abolished by indomethacin, andsignificantly inhibited by rofecoxib.These drugs inhibit the enzymes COX-1 and COX-2, which play a key role in maintaining the health of the stomach lining.
The researchers concluded that the extract accelerates ulcer healing viaa mechanism involving COX-1 and COX-2 activity, combined with effects on gastric acid, gastric blood flow at the ulcer margin and release of gastrin, which promotes ulcer healing.
"Because grapefruit is acidic in nature, people with ulcers might assume that they should not include the fruit in their diet," said lead author Dr Thomas Brzozowski.
"However, this research suggests the exact opposite. The antioxidant properties found in grapefruit and the ability of this fruit extract to limit oxidative stress in the ulcerative gastric mucosa have therapeutic properties that, when combined with additional therapies, can be especially beneficial for healing of gastric ulcers."
Ulcers can result when the stomach produces excess acid or there is insufficient mucus to protect the lining from damage. Infection with the Helicobacter pylori significantly raises the risk of ulcers, as does regular use of certain medicines like aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs).
Smoking, drinking and a fatty diet are also linked to ulcers.
About 20 million Americans develop at least one ulcer during their lifetime and more than 40,000 Americans have surgery because of persistent symptoms or problems from ulcers every year.