Helicobacter pylori--in vitro susceptibility to garlic (Allium sativum) extract

The protective effect of Allium sativum L. clove aqueous and methanolic extracts against hypoxia-induced lethality in mice

The antihypoxic activity of Allium sativum clove (garlic) aqueous and methanolic extracts was studied in mice. The extracts of garlic showed that the antihypoxic effect was dose-dependent. The minimum effective doses of aqueous and methanolic extracts were 0.2 g/kg and 5.12 g/kg, respectively. Phenytoin, 50 mg/kg, and R-phenylisopropyladenosine (R-PIA), 1.6 mg/kg (R-PIA) as positive controls increased survival time up to 52.5 +/- 2.9 min and 120.5 +/- 6 min, respectively, compared to normal saline (34.73 +/- 0.71 min). The high doses of aqueous (16.9 g/kg) and methanolic (12.8 g/kg) extracts increased survival time up to 73.17 +/- 4.9 and 68.41 +/- 3.7, respectively. These results indicated that the extracts of A. sativum cloves have a protective effect against hypoxia-induced lethality in mice.

In vitro susceptibility of Helicobacter pylori to isoquinoline alkaloids from Sanguinaria canadensis and Hydrastis canadensis

Methanol extracts of the rhizomes of Sanguinaria canadensis, and the roots and rhizomes of Hydrastis canadensis, two plants used traditionally for the treatment of gastrointestinal ailments, were screened for in vitro antibacterial activity against 15 strains of Helicobacter pylori. The rhizome extracts, as well as a methanol extract of S. canadensis suspension-cell cultures inhibited the growth of H. pylori in vitro, with a MIC50 range of 12.5-50.0 microg/ml. Three isoquinoline alkaloids were identified in the active fraction. Sanguinarine and chelerythrine, two benzophenanthridine alkaloids, inhibited the growth of the bacterium, with an MIC50 of 50.0 and 100.0 microg/ml, respectively. Protopine, a protopine alkaloid, also inhibited the growth of the bacterium, with a MIC50 of 100 microg/ml. The crude methanol extract of H. canadensis rhizomes was very active, with an MIC50 of 12.5 microg/ml. Two isoquinoline alkaloids, berberine and beta-hydrastine, were identified as the active constituents, and having an MIC50 of 12.5 and 100.0 microg/ml, respectively.

Suppressive effects of garlic extract on Helicobacter pylori-induced gastritis in Mongolian gerbils

Helicobacter pylori infection is intimately involved in stomach cancer development and recent epidemiological studies have indicated that the consumption of allium vegetables reduces the risk of gastric neoplasia. Therefore, in the present study, we investigated the effect of a garlic extract on H. pylori-induced gastritis in Mongolian gerbils. Garlic extract was fed to animals at doses of 1, 2 and 4% in the diet from 4 h after H. pylori inoculation until the end of the experiment, at week 6. With the administration of garlic extract, H. pylori-induced gastritis in animals was decreased in a dose-dependent manner, and significantly so at 4%. The numbers of hemorrhagic spots in the glandular stomach and the microscopic score for gastritis were significantly reduced from 19.2+/-15.6 and 5.9+/-0.8 in control gerbils to 8.1+/-11.2 and 4.2+/-1.5, respectively, by 4% garlic extract treatment. The stomach wet weight (1.04+/-0.22 g) of control gerbils was also reduced by 4% garlic extract (0.86+/-0.18 g). However, the number of viable H. pylori was not changed by the garlic extract treatment. The above observations indicated that garlic extract might be useful as an agent for prevention of H. pylori-induced gastritis, leading to reduction in the risk of gastric cancer.

Helicobacter pylori infection in rural China: demographic, lifestyle and environmental factors

BACKGROUND

Although Helicobacter pylori is one of the most common human bacterial infections worldwide, its mode of transmission is unclear.

METHODS

To investigate possible associations between H. pylori infection and demographic, lifestyle, and environmental factors in a rural Chinese population, a cross-sectional survey was administered to 3288 adults (1994 seropositive, 1019 seronegative, 275 indeterminate) from 13 villages in Linqu County, Shandong Province, China.

RESULTS

Helicobacter pylori prevalence was elevated for: infrequent handwashing before meals (OR = 1.7, 95% CI: 1.0-3.0), crowding (i.e. sharing a bed with >2 people [OR = 2.3, 95% CI: 1.3-4.2]), washing/bathing in a pond or ditch (OR = 1.5, 95% CI: 1.0-2.4), and medium (OR = 1.6, 95% CI: 1.3-2.0) and low (OR = 2.3, 95% CI: 1.9-2.9) compared to high village education level, and reduced for never being married or divorced (OR = 0.4, 95% CI: 0.2-1.0). There was also a suggestion that source of drinking water, especially water from a shallow village well might be related to H. pylori seropositivity. There was no evidence of an association between H. pylori prevalence and alcohol or tobacco use, raw fruit and vegetable intake, or individual social class measures.

CONCLUSIONS

The results of this study suggest that person-to-person transmission is the most plausible route of H. pylori infection in this rural Chinese population, but waterborne exposures deserve further investigation.

Protection of N-methyl-N'-nitro-N-nitrosoguanidine-induced in vivo clastogenicity by aqueous garlic extract

The modulatory effects of garlic extract on the in vivo clastogenicity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), a carcinogenic nitrosamine, were evaluated by quantification of micronuclei and chromosomal aberrations in metaphase cells from the bone marrow of male Wistar rats. A single intraperitoneal injection of MNNG (40 mg/kg bodyweight) was found to be clastogenic as revealed by the increased frequency of micronucleated polychromatic erythrocytes and chromosomal aberrations. Pretreatment with aqueous garlic extract (250 mg/kg bodyweight) for 5 days significantly reduced the frequencies of MNNG-induced micronuclei and chromosomal aberrations. The results demonstrate that administration of garlic extract protects against the clastogenic effects of MNNG.

Helicobacter pylori prevalence and CagA status among children in two counties of China with high and low risks of gastric cancer

BACKGROUND

Studies in adult populations in selected countries with widely varying rates of gastric cancer have shown a weak correlation between gastric cancer mortality rates and the prevalence of CagA+ strains of H. pylori. However, only limited data are available in ethnically homogenous populations with varying rates in the same region. METHODS; We compared the prevalence of H. pylori in general and of CagA+ strains in particular among children in Shandong Province, China in areas at high (Linqu County) and low risk (Cangshan County) of gastric cancer. H. pylori status among children aged 3 to 12 years was determined by 13C-UBT, and CagA status was determined by enzyme-linked immunosorbent assay (ELISA). Because of the difficulty in obtaining blood from young children aged 3 to 4 years and from some children aged 5 years, CagA status was determined among part of children 5 years old and children 6 to 12 years old. RESULTS; Among 98 children aged 3 to 12 years in Linqu, 68 (69.4%) was H. pylori-positive, as compared with 29 (28.7%) among 101 children in Cangshan. Among children positive for 13C-UBT, the proportion of the CagA+ strains were identified was 46 (88.5%) of 52 in Linqu and 13 (81.3%) of 16 in Cangshan, respectively.

CONCLUSIONS

The prevalence of H. pylori was nearly three times higher among children in Linqu than in Cangshan, which may contribute to the large differential in gastric cancer rates for two neighboring populations in Shandong Province.

A pilot study to determine the effectiveness of garlic oil capsules in the treatment of dyspeptic patients with Helicobacter pylori

BACKGROUND

Resistance of Helicobacter pylori to clarithromycin and metronidazole is now found worldwide. Steam-distilled garlic oil has in vitro activity against H. pylori and may be a useful alternative treatment strategy.

MATERIALS AND METHODS

In this pilot study dyspeptic patients with positive serology for H. pylori confirmed by 13C urea breath test (UBT), at 0 and 2 weeks, were enrolled. Treatment consisted of one 4 mg garlic oil capsule with a meal four times per day for 14 days. H. pylori eradication was defined as a negative UBT at both follow-up appointments. Suppression was defined as a 50% fall in 13C excess between baseline and follow-up 1.

RESULTS

Five patients completed the study. There was no evidence of either eradication or suppression of H. pylori or symptom improvement whilst taking garlic oil.

CONCLUSION

These negative results show that, within the gastric milieu, garlic oil at this dose does not inhibit H. pylori. A higher dose administered for a longer time-period may be effective. Antibiotics are usually combined with a proton-pump inhibitor or bismuth salt, as the only antibiotic with any in vivo activity against H. pylori in monotherapy is clarithromycin. A proton pump inhibitor raises gastric pH and, by increasing bacterial division, may increase the in vivo activity of garlic oil. This may be worth pursuing in a future trial.

Plant foods and risk of gastric cancer: a case-control study in Uruguay

The association between plant foods intake and gastric cancer risk was investigated in a Uruguayan study on environmental factors and cancer. The study included 160 newly diagnosed and histologically verified cases of gastric carcinoma and 320 hospitalized controls. These controls were frequency-matched to the cases on age, sex, residence and urban/rural status. Total vegetable intake was associated with a reduction in risk (odds ratio (OR) 0.64, 95% confidence interval (CI) 0.38-1.08), which was markedly attenuated after adjustment for total fruit intake. The only group of vegetables that persisted as significantly protective after controlling for total energy and total fruit consumption were allium vegetables (OR 0.56, 95% CI 0.34-0.92). On the other hand, total fruit consumption displayed a strong inverse association after controlling for total vegetable intake (OR 0.35, 95% CI 0.21-0.59). Neither tubers nor pulses were associated with gastric cancer risk. Finally, total plant foods were strongly associated with a reduced risk of stomach cancer (OR 0.31, 95% CI 0.18-0.54). It is suggested that vitamins (vitamin C and carotenoids) and bioactive substances (diallyl sulfide) could be involved in the mechanisms of action of plant foods.

Protection against Helicobacter pylori and other bacterial infections by garlic

Louis Pasteur was the first to describe the antibacterial effect of onion and garlic juices. Historically, garlic has been used worldwide to fight bacterial infections. Allium vegetables, particularly garlic (Allium sativum L.) exhibit a broad antibiotic spectrum against both gram-positive and gram-negative bacteria. Noteworthy results published include the following: 1) raw juice of garlic was found to be effective against many common pathogenic bacteria-intestinal bacteria, which are responsible for diarrhea in humans and animals; 2) garlic is effective even against those strains that have become resistant to antibiotics; 3) the combination of garlic with antibiotics leads to partial or total synergism; 4) complete lack of resistance has been observed repeatedly; 5) even toxin production by microorganisms is prevented by garlic. Helicobacter pylori (H. pylori) is a bacterium implicated in the etiology of stomach cancer and ulcers. The incidence of stomach cancer is lower in populations with a high intake of allium vegetables. We have demonstrated in vitro that H. pylori is susceptible to garlic extract at a fairly moderate concentration. Even some antibiotic-resistant H. pylori strains are susceptible to garlic. Clinical trials are necessary to explore the possibility of using garlic as a low-cost remedy for eradicating H. pylori.

Garlic and cancer: a critical review of the epidemiologic literature

Animal and in vitro studies provide evidence of an anticarcinogenic effect of active ingredients in garlic. This review of the epidemiologic literature on garlic consumption addresses cancers of the stomach, colon, head and neck, lung, breast and prostate. Nineteen studies reported relative risk estimates for garlic consumption and cancer incidence. Site-specific case-control studies of stomach and colorectal cancer, in which multiple reports were available, suggest a protective effect of high intake of raw and/or cooked garlic. Cohort studies confirm this inverse association for colorectal cancer. Few cohort and case-control studies for other sites of cancer exist. Garlic supplements, as analyzed in four cohort studies and one case-control report, from two distinct populations, do not appear to be related to risk. Low study power, lack of variability in garlic consumption categorization within studies and poor adjustment for potential cofounders may limit the reliability of any conclusions regarding garlic supplements. However, an indication of publication bias was also found by visual inspection of a funnel plot and in a log-rank test (P = 0.004). Evidence from available studies nevertheless suggests a preventive effect of garlic consumption in stomach and colorectal cancers. The study limitations indicate the need for more definitive research and improved nutritional epidemiologic analyses of dietary data.

Activities of garlic oil, garlic powder, and their diallyl constituents against Helicobacter pylori

Chronic Helicobacter pylori disease is reduced with Allium vegetable intake. This study was designed to assess the in vivo anti-H. pylori potential of a variety of garlic substances. The garlic materials all showed substantial but widely differing anti-H. pylori effects against all strains and isolates tested. The MICs (range, 8 to 32 microg/ml) and minimum bactericidal concentrations (MBCs) (range, 16 to 32 microg/ml) of undiluted garlic oil (GO) were smaller than those of garlic powder (GP) (MIC range, 250 to 500 microg/ml; MBC range, 250 to 500 microg/ml) but greater than the MIC of allicin (4. 0 microg/ml) (Table 2) present in GP. Allicin (MIC, 6 microg/ml; MBC, 6 microg/ml) was more potent than diallyl disulfide (MIC range, 100 to 200 microg/ml; MBC range, 100 to 200 microg/ml), its corresponding sulfide, but of a strength similar to that of diallyl tetrasulfide (MIC range, 3 to 6 microg/ml; MBC range, 3 to 6 microg/ml). Antimicrobial activity of the diallyl sulfides increased with the number of sulfur atoms. Time course viability studies and microscopy showed dose-dependent anti-H. pylori effects with undiluted GO, GP, allicin, and diallyl trisulfide after a lag phase of ca. 1 to 2 h. Substantial in vitro anti-H. pylori effects of pure GO and GP and their diallyl sulfur components exist, suggesting their potential for in vivo clinical use against H. pylori infections.

Nutritional factors in human cancers

A variety of external factors interacting with genetic susceptibility influence the carcinogenesis process. External factors including oxidative compounds, electrophilic agents, and chronic infections may enhance genetic damage. In addition, various hormonal factors which influence growth and differentiation are critically important in the carcinogenic process. Diet and nutrition can influence these processes directly in the gastrointestinal tract by providing bioactive compounds to specific tissues via the circulatory system, or by modulating hormone levels. Differences in certain dietary patterns among populations explain a substantial proportion of cancers of the colon, prostate and breast. These malignancies are largely influenced by a combination of factors related to diet and nutrition. Their causes are multifactorial and complex, but a major influence is the widespread availability of energy-dense, highly processed and refined foods that are also deplete in fiber. These dietary patterns in combination with physical inactivity contribute to obesity and metabolic consequences such as increased levels of IGF-1, insulin, estrogen, and possibly testosterone. These hormones tend to promote cellular growth. For prostate cancer, epidemiologic studies consistently show a positive association with high consumption of milk, dairy products, and meats. These dietary factors tend to decrease 1.25(OH)2 vitamin D, a cell differentiator, and low levels of this hormone may enhance prostate carcinogenesis. While the nutritional modulation of growth-enhancing and differentiating hormones is likely to contribute to the high prevalence of breast, colorectal, prostate, and several other cancers in the Western world, these cancers are relatively rare in less economically developed countries, where malignancies of the upper gastrointestinal tract are quite common. The major causes of upper gastrointestinal tract cancers are likely related to various food practices or preservation methods other than refrigeration, which increase mucosal exposure to irritants or carcinogens.

Health effects of vegetables and fruit: assessing mechanisms of action in human experimental studies

Epidemiologic data support the association between high intake of vegetables and fruits and low risk of chronic disease. There are several biologically plausible reasons why consumption of vegetables and fruit might slow or prevent the onset of chronic diseases. Vegetables and fruit are rich sources of a variety of nutrients, including vitamins, trace minerals, and dietary fiber, and many other classes of biologically active compounds. These phytochemicals can have complementary and overlapping mechanisms of action, including modulation of detoxification enzymes, stimulation of the immune system, reduction of platelet aggregation, modulation of cholesterol synthesis and hormone metabolism, reduction of blood pressure, and antioxidant, antibacterial, and antiviral effects. Although these effects have been examined primarily in animal and cell-culture models, experimental dietary studies in humans have also shown the capacity of vegetables and fruit and their constituents to modulate some of these potential disease-preventive mechanisms. The human studies have relied on intermediate endpoints related to disease risk. Design methodologies used include multiple-arm trials, randomized crossover studies, and more compromised designs such as nonrandomized crossovers and pre- and posttreatment analyses. Length of treatment ranged from a single dose to years depending on the mechanism of interest. Stringency of dietary control varied from addition of supplements to a habitual diet to provision of all food for the duration of a treatment. Rigorously conducted experimental dietary studies in humans are an important link between population- and laboratory-based research.

Prospects for cancer prevention

As in many other countries, the New Zealand Cancer Society produces guidelines for cancer prevention. These recommend avoiding asbestos, smoking, sunlight, alcohol, fatty food and obesity. Women are advised to have a regular cervical smear test. Additional 'probably helpful' suggestions include eating plenty of fresh fruit and vegetables and dietary fibre. However, considerable data from animal studies and more slowly accumulating data from human intervention studies suggest additional and more specific advice may be appropriate. Fruit and vegetable servings should total a minimum of five each day. Some specific fruits and vegetables (e.g., tomato, broccoli, onions) may have particular benefits against individual cancer types. Positive human evidence on potential benefits of increasing dietary fibre comes from studies where wheat bran was added to the diet. This is not a dietary fibre per se, but merely a good fibre source. Indeed, our own studies suggest that it could be various phytochemicals in the bran, rather than dietary fibre, which is beneficial. An increase either in whole wheat or wheat bran, rather than fibre, would be a sounder recommendation. Although there is some evidence that multivitamin supplementation can protect against cancer, this may be only in the special situation where the population is already significantly vitamin-deficient. For example, a combination of beta-carotene, vitamin E and selenium significantly reduced cancer mortality in a Chinese population, whereas lung cancer risks (in already high risk groups) were increased in Finnish and American trials with high dose beta-carotene. Various other chemopreventive drugs are being actively developed and at various stages in clinical trials. The enhanced cancer incidence in the beta-carotene trial illustrates the potential benefit of utilising surrogate endpoints of malignant disease rather than incident cancer as a trial endpoint.

Antibacterial effect of garlic and omeprazole on Helicobacter pylori

The antibacterial effect of a home-made raw garlic extract and commercial garlic tablets alone and in combination with antibiotics or omeprazole was determined against clinical isolates of Helicobacter pylori. MIC values of raw garlic extract and three types of commercial garlic tablets ranged from 10,000 to 17,500 mg/L. When MIC values of the commercial tablets were based on the allicin content, no differences between the three types were observed. The combination of garlic and omeprazole, studied with killing curves, showed a synergic effect which was concentration dependent. Further clinical evaluation of garlic in combination with the conventional agents for H. pylori treatment seems warranted.

Helicobacter Pylori

All infected patients with a peptic ulcer should be treated for H. pylori. The role of treating H. pylori in patients with undiagnosed dyspepsia or non-ulcer dyspepsia, those taking nonsteroidal anti-inflammatory medications, or with a family history of gastric cancer remains controversial. Triple therapies consisting of a proton pump inhibitor or ranitidine bismuth citrate and two antibiotics are the current standard of therapy for H. pylori. In general, dual therapies should no longer be used to treat H. pylori. Bismuth triple therapy consisting of bismuth, tetracycline, and metronidazole is a less expensive alternative to proton pump inhibitor-or ranitidine bismuth citrate-based triple therapies. However, bismuth triple therapy is hampered by frequent side effects and the need for qid dosing. In Europe, a 7-day course of therapy appears to be adequate. In the United States, 10-14 days of therapy are currently recommended. Metronidazole resistance in H. pylori strains varies geographically, and negatively influences the effectiveness of therapies containing this antibiotic. Clarithromycin resistance is relatively infrequent at the current time but may be rising in countries where this antibiotic is in use. If a patient remains infected after a course of therapy for H. pylori, the second treatment should avoid the antibiotics used initially.

Protective effect of allium vegetables against both esophageal and stomach cancer: a simultaneous case-referent study of a high-epidemic area in Jiangsu Province, China

To study the relation between allium vegetable intake and cancer of the esophagus (EC) and stomach (SC) in Yangzhong city, which is one of the highest-risk areas for these cancers in Jiangsu province, China, a simultaneous case-referent study was conducted using histopathologically confirmed cases (EC: n = 81, SC: n = 153) and population-based referents (n = 234). A questionnaire was used to collect information on the general status of subjects, their dietary habits, frequency intake of allium vegetables and other foods, tea consumption, smoking and alcohol drinking. The odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by a multiple logistic regression model. The results showed that frequent intake of allium vegetables (including garlic, onion, Welsh onion and Chinese chives), raw vegetables, tomatoes and snap beans, and tea consumption were inversely associated with the risk for EC and SC. In the highest consumption category (> or = 1 time/week) of garlic, onion, Welsh onion and Chinese chives, the adjusted ORs compared with the lowest category (< 1 time/month) were 0.30 (CI = 0.19-0.47), 0.25 (CI = 0.11-0.54), 0.15 (CI = 0.08-0.26), and 0.57 (CI = 0.23-1.42) for EC, and 0.31 (CI = 0.22-0.44), 0.17 (CI = 0.08-0.36), 0.22 (CI = 0.15-0.31) and 0.40 (CI = 0.17-0.94) for SC, respectively. The main results in the present study suggested that allium vegetables, like raw vegetables, may have an important protecting effect against not only stomach cancer, but also esophageal cancer.

Garlic or jalapeño peppers for treatment of Helicobacter pylori infection

OBJECTIVE

There have been a number of reports that natural foods such as garlic, honey, and capsaicin can inhibit Helicobacter pylori in vitro and each report has suggested the natural ingredient be used for treatment of the infection. We investigated whether garlic or capsaicin-containing peppers would actually inhibit H. pylori in vivo.

METHODS

We performed a prospective crossover study in healthy H. pylori-infected adults. We used the urea breath test to assess the status of the H. pylori infection. On separate days subjects received three test meals consisting of beef, tortillas, and salad with one of the following: fresh garlic (10 sliced cloves), capsaicin (six sliced fresh jalapeños), two tablets of bismuth subsalicylate (Pepto-Bismol, positive control), or nothing added (negative control). Breath testing was done before the first meal, the evening meal, and the following morning. At least 2 days elapsed between the test substances.

RESULTS

Twelve subjects participated (seven men, five women), with an average age of 41.4 yr, range 27-51 yr. Ten subjects received garlic, six received jalapeños, and 11 received bismuth. Neither garlic nor capsaicin had any in vivo effect on H. pylori (median urease activity 28.5 vs 39.8 and 43.7 vs 46.6 before and after garlic and jalapeños, respectively) (p > 0.8). Bismuth had a marked inhibitory effect (median 55.8 vs 14.3 before and after bismuth) (p < 0.001), respectively.

CONCLUSIONS

This study did not support a role for either garlic or jalapeños in the treatment of H. pylori infection. Caution must be used when attempting to extrapolate data from in vitro studies to the in vivo condition.