Grape Seed Extract
Its abundance of polyphenols and high bioavailability make grape seed extract one of nature’s most powerful antioxidants. Grape seed extract protects multiple organs against the toxic effects of diverse drugs and chemicals, while also enhancing the growth and viability of normal cells.81 Grape seed’s proanthocyanidins protect against chemotherapeutic drug-induced cytotoxicity in human liver cells, as well as against a variety of liver-toxic drugs such as acetaminophen.81
Grape seed proanthocyanidins prevent the oxidative stress that ordinarily occurs after a high-fat meal.82 They also prevent organ toxicity by minimizing lipid peroxidation and preventing glutathione depletion.83 Grape seed extract has been shown to be effective in preventing diseases associated with alcohol consumption, including gastric ulcers, large bowel cancer, cataracts, and diabetes.84 In human trials, grape seed was shown to prevent increased lipid peroxides in human plasma after exercise and to lessen muscle fatigue after weight training.84
Grape seed extract also causes a dose-dependent lowering of the liver’s cytochrome P450 2E1 drug-metabolizing enzyme, which is normally elevated in chronic drinkers. This enzyme is responsible for converting pesticides and other chemicals into highly toxic metabolites. In non-drinkers, who have lower levels of cytochrome P450 2E1 than drinkers, many pesticides are not converted into more toxic metabolites.81
|Milk Thistle (Silybum marianum) |
Milk Thistle Extract
In folk medicine, milk thistle extract (Silybum marianum) traditionally has been used as a liver tonic. It has long been believed that this prickly weed, related to the artichoke, protects the liver against a variety of ailments. In the case of milk thistle, modern science has shown that ancient beliefs about a purported healing herb are based on verifiable fact.
Numerous studies have shown that this archaic remedy fights inflammation and enhances the immune system. In fact, silibinin and silymarin—the two flavonoid compounds that serve as the active ingredients in milk thistle extract—are used clinically to treat liver toxicity in Europe and Asia. Studies suggest that in addition to protecting the liver, silymarin and silibinin may also help prevent cancers of the prostate, lungs, and skin, among other organs.85-93
In Vienna, scientists conducted a randomized, double-blind study of silymarin in 170 patients with liver cirrhosis. The patients, more than half of whom suffered from alcoholic cirrhosis, received 140 mg of silymarin three times daily for an average of three and a half years. Silymarin significantly improved the four-year survival rate among cirrhosis patients, including those with alcoholic cirrhosis, in contrast to control subjects who did not receive the herbal supplement. No side effects of silymarin treatment were observed, despite up to four years of continuous treatment.94
Scientists in India recently described the results of a clinical trial in which silymarin reversed markers of liver distress in patients receiving a powerful cocktail of drugs for the treatment of tuberculosis. The drugs are known to increase lipid peroxidation in the
liver while depleting glutathione and raising levels of various enzymes associated with liver disease or injury. When elevated, these marker enzymes indicate pathological stress in the liver. When silymarin was administered with the antibiotic drugs, these indicators of liver health improved significantly.95
Charles S. Lieber, MD, a leading researcher in the field of alcoholic liver disease, examined silymarin’s effects on alcohol-induced liver fibrosis in baboons. “Silymarin opposed the alcohol-induced oxidative stress,” in the subjects’ livers, wrote Lieber’s research team. Noting that silymarin significantly slowed the development of alcohol-induced hepatic fibrosis, the researchers emphasized that their findings echo the results of previous studies.”96
Another exotic herb handed down by traditional medicine is Picrorhiza kurroa. A small, increasingly rare perennial herb that grows at high altitudes in the Himalayan region, Picrorhiza kurroa is prized for its liver-protecting properties.97
Picrorhiza has been shown to stimulate liver regeneration in rats, possibly by stimulating nucleic acid and protein synthesis.98 Scientists in India examined the effects of picroliv, the active constituent isolated from Picrorhiza kurroa, on alcohol-induced liver injury in living rats. Although alcohol induced various markers of liver distress, the herb improved all measured parameters of liver health.99 Its mechanism of action and efficacy appear to be similar to that of milk thistle extract, though picroliv may be even more effective than silymarin and silibinin in protecting the liver from toxic insult.97
Another study conducted in India examined picroliv’s effects on the livers of laboratory rats that were exposed to a known carcinogen. The toxin caused predictable effects, including increased lipid peroxidation and depletion of key antioxidants. Levels of antioxidants, including glutathione, were restored to normal in the livers of picroliv-treated rats. Microscopic examination of the animals’ liver tissue showed evidence of severe damage among the control animals, including cell death, inflammation, and growth of cancerous tissue. By contrast, the picroliv-fed rats had virtually normal liver tissue.100
Numerous other studies have investigated picroliv’s liver-protective effects against various toxic and biological insults, including alcohol, hepatitis virus, and various carcinogenic chemicals. All reported a significant protective effect.99-104 Although most studies have involved laboratory animals or cell cultures, human studies have also demonstrated efficacy. For example, in a randomized, double-blind, placebo-controlled trial of patients diagnosed with acute viral hepatitis, Picrorhiza kurroa extract was shown to significantly improve markers of liver health and function in supplemented patients as compared to control subjects.101
Ironically, a constituent of wine may hold one of the keys to protecting the liver against alcohol-induced damage. Found in a variety of foods such as cranberries, peanuts, and grapes, resveratrol is a natural antioxidant. Abundant in red wine, it is believed to play an important role in the purported benefits of moderate wine consumption.
Known as a phytoalexin—that is, a plant chemical responsible for preventing damage to plant tissue—and classified chemically as a polyphenolic stilbene, resveratrol has been shown to reduce both low-density lipoprotein (LDL) oxidation and the stickiness of platelets, two effects that may account for its cardioprotective benefits.105
As Spanish scientists recently noted, “Multiple lines of compelling evidence indicate [resvera-trol’s] beneficial effects on neurological, [liver], and cardiovascular systems.”106 This research team also concluded that resveratrol “blocks the multistep process of carcinogenesis at various stages: tumor initiation, promotion, and progression.”106 Other research suggests that resveratrol may help inhibit the growth of certain cancers.107 Resveratrol is thought to fight cancer by halting runaway inflammation through various discrete mechanisms, including inhibition of synthesis and release of pro-inflammatory mediators, inhibition of activated immune cells, and modification of eicosanoid synthesis.106
|Barley (Hordeum vulgare) |
Barley green extract has been credited with reducing damage from alcohol’s oxidation to acetaldehyde in the body. Young green barley leaves contain flavonoid antioxidants, including the flavone-C-glycosides saponarin and lutonarin.108 Studies have shown that barley green extract inhibits the generation of superoxide and hydroxyl radicals in a dose-related manner.109
Moreover, tests using a rabbit model of human atherosclerosis have shown that barley leaf extract reduces atherosclerosis caused by excessively high blood lipids by 30% compared to control animals. “This 30% inhibition . . . was associated with a decrease in plasma lipids and an increase in antioxidative abilities,” noted a research team from Taiwan.110 The same team investigated the effects of young barley leaf extract on LDL oxidation and free radical scavenging activities in human patients with type II diabetes. Such individuals are at increased risk of cardiovascular disease. The study determined that barley leaf extract inhibited LDL oxidation and helped to scavenge oxygen free radicals.111
While moderate alcohol consumption—particularly of resveratrol-rich red wine—may benefit the cardiovascular system,10,11 chronic alcohol abuse is anything but healthful.
To guard against the toxic effects of acetaldehyde and increased free radical production generated by alcohol metabolism, it is advisable to use supplements that may prevent or ameliorate the potential damage.