Effect of the essential oils of garlic and onion on alimentary hyperlipemia

Cholesterol-lowering activity of natural mono- and sesquiterpenoid compounds in essential oils: A review and investigation of mechanisms using in silico protein-ligand docking

Mono- and sesquiterpenoids are the main chemical constituents of essential oils. Essential oils and their constituents have received increasing attention for lipid-lowering properties in both cell and animal models. Despite the chemical diversity of essential oil compounds, the effects of many of these compounds on cholesterol metabolism are highly similar. In this report, we review the literature regarding the effects of essential oils and their terpenoid constituents on cholesterol homeostasis, and explore likely mechanisms using protein-ligand docking. We identified 98 experimental and seven clinical studies on essential oils, isolated compounds, and blends; 100 of these described improvements either in blood cholesterol levels or in sterol metabolic pathways. Our review and docking analysis confirmed two likely mechanisms common to many essential oil compounds: (1) direct agonism of peroxisome-proliferator-activated receptors, and (2) direct interaction with sterol-sensing domains, motifs found in key sterol regulatory proteins including sterol regulatory element binding protein cleavage activating protein and HMG-CoA reductase. Notably, these direct interactions lead to decreased transcription and accelerated degradation of HMG-CoA reductase. Our work suggests that terpene derivatives in essential oils have cholesterol-lowering activity and could potentially work synergistically with statins, however, further high quality studies are needed to establish their clinical efficacy.

A comparative analysis of the essential oils from two species of garlic seedlings cultivated in China: chemical profile and anticoagulant potential

Garlic seedlings (GS) and blanched garlic seedlings (BGS) are two kinds of common garlic-derived vegetables in China, but little information is available on their bioactive constituents. In this work, chemical profiles and anticoagulant activities of essential oils from GS (EOGS) and BGS (EOBGS) were disclosed and compared for the first time. Sixteen and fourteen volatile compounds were identified in EOGS and EOBGS by GC-MS analysis, and both of them were rich in sulfur-containing compounds, particularly diallyl sulfides accounting for 74.77% and 85.87%, respectively. EOGS and EOBGS exerted anticoagulant activities via intrinsic, extrinsic, and common coagulation pathways as well as by lowering the content of fibrinogen; EOGS exceeded EOBGS in the activation of intrinsic and extrinsic coagulation pathways, while EOBGS outperformed EOGS on the activation of the common coagulation pathway, which was even superior to that of heparin at the same dose. Herein, the results of the present investigation will give a strong clue that EOGS and EOBGS are more likely to lead to a promising way to vegetable-based anticoagulants.

Effect of Steamed Onion (ONIRO) Consumption on Body Fat and Metabolic Profiles in Overweight Subjects: A 12-Week Randomized, Double-Blind, Placebo-Controlled Clinical Trial

Objective: The aim of the study is to investigate the effect of Jeju steamed onion (ONIRO) on body fat and metabolic profiles in overweight subjects.Methods: This randomized, double-blind, placebo-controlled clinical intervention was conducted and completed at one clinical research site. The subjects (n = 70) were randomly divided into placebo or test group and were instructed to take before each meal either the placebo or ONIRO capsule for 12 weeks. Anthropometric as well as serum and metabolic parameters, including triglycerides, cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, leptin, adiponectin, C-peptide, and aspartate aminotransferase (AST) were measured at baseline and after 12 weeks. Body composition was also measured by dual-energy x-ray absorptiometry (DEXA) and computed tomography (CT). This trial is registered under the trial registration code clinicaltrials.gov: NCT03645382 (https://register.clinicaltrials.gov).Results: Compared to the placebo, ONIRO supplementation for significantly reduced the percentage of body fat and fat mass as measured by DEXA (p = 0.028 and 0.022, respectively) with no significant effects on lean body mass. CT analyses at the L1 level showed a significant decrease in the areas of whole fat, visceral fat, and subcutaneous fat (p = 0.009, p = 0.039, p = 0.020, respectively), while CT scan of L4 resulted in a significant reduction of whole fat area and subcutaneous area (p = 0.006 and p = 0.012, respectively). The levels of triglycerides (TG) and C-peptide were significantly lower after 12 weeks of ONIRO treatment.Conclusions: These findings suggest that ONIRO supplementation reduces total body fat, notably abdominal visceral fat, with positive changes of the clinically relevant metabolic parameters serum TG and C-peptide.

Anti-Aggregatory Potential of Selected Vegetables-Promising Dietary Components for the Prevention and Treatment of Cardiovascular Disease

Increased blood platelet activation, especially platelet aggregation, plays an important function in cardiovascular disease; however, various dietary components may inhibit platelet activation. Recent clinical and epidemiologic studies indicate that both fruits and vegetables, and their products, contain various phytoprotective substances possessing biological properties such as antiplatelet and antioxidant effects that may work synergistically to ameliorate the effect of cardiovascular disease. In addition, the consumption of vegetables and their products may also play an important role in prevention. However, the mechanisms involved have not been clearly defined. Various studies clearly indicate that certain vegetables (e.g., onions, garlic, and tomatoes) have beneficial effects on blood platelet hyperactivity, an important cardiovascular risk factor, and hence may offer new prophylactic and therapeutic possibilities for the treatment of blood platelet hyperactivation and cardiovascular disease. This mini-review evaluates the current literature on the relationship between the consumption of onion (Allium cepa L.), garlic (Allium sativum L.), tomato (Solanum lycopersicum L.), and beetroot (Beta vulgaris L.), and blood platelet activation, which may have important implications for the prophylaxis and treatment of cardiovascular disease.

Onion Peel Ethylacetate Fraction and Its Derived Constituent Quercetin 4'-O-β-D Glucopyranoside Attenuates Quorum Sensing Regulated Virulence and Biofilm Formation

The resistance and pathogenesis of bacteria could be related to their ability to sense and respond to population density, termed quorum sensing (QS). Inhibition of the QS system is considered as a novel strategy for the development of antipathogenic agents, especially for combating drug-resistant bacterial infections. In the present study, the anti-QS activity of Onion peel ethylacetate fraction (ONE) was tested against Chromobacterium violaceum CV12472 and Pseudomonas aeruginosa PAO1. ONE inhibit the QS-mediated virulence factors production such as violacein in C. violaceum and elastase, pyocyanin in P. aeruginosa. Further, the treatment with sub-MICs of ONE significantly inhibited the QS-mediated biofilm formation, EPS (Extracellular polymeric substances) production and swarming motility. Further, quercetin 4′-O-β-D glucopyranoside (QGP) was isolated from ONE and its anti-QS potential was confirmed after observing significant inhibition of QS-controlled virulence factors such as violacein, elastase, pyocyanin and biofilm formation in test pathogens. Molecular docking analysis predicted that QGP should be able to bind at the active sites of Vfr and LasR, and if so blocks the entry of active sites in Vfr and LasR.

The Chemical Compositions of the Volatile Oils of Garlic (Allium sativum) and Wild Garlic (Allium vineale)

Garlic, Alliumsativum, is broadly used around the world for its numerous culinary and medicinal uses. Wild garlic, Allium vineale, has been used as a substitute for garlic, both in food as well as in herbal medicine. The present study investigated the chemical compositions of A. sativum and A. vineale essential oils. The essential oils from the bulbs of A. sativum, cultivated in Spain, were obtained by three different methods: laboratory hydrodistillation, industrial hydrodistillation, and industrial steam distillation. The essential oils of wild-growing A. vineale from north Alabama were obtained by hydrodistillation. The resulting essential oils were analyzed by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Both A. sativum and A. vineale oils were dominated by allyl polysulfides. There were minor quantitative differences between the A. sativum oils owing to the distillation methods employed, as well as differences from previously reported garlic oils from other geographical locations. Allium vineale oil showed a qualitative similarity to Allium ursinum essential oil. The compositions of garlic and wild garlic are consistent with their use as flavoring agents in foods as well as their uses as herbal medicines. However, quantitative differences are likely to affect the flavor and bioactivity profiles of these Allium species.

Effect of Garlic and Lemon Juice Mixture on Lipid Profile and Some Cardiovascular Risk Factors in People 30-60 Years Old with Moderate Hyperlipidaemia: A Randomized Clinical Trial

BACKGROUND

This study was performed to effects of garlic and lemon juice mixture on lipid profile and some cardiovascular risk factors in people 30-60 years old with moderate hyperlipidemia.

METHODS

In a parallel-designed randomized controlled clinical trial, a total of 112 hyperlipidemic patients 30-60 years, were recruited from Isfahan Cardiovascular Research Center. People were selected and randomly divided into four groups. Control blood samples were taken and height, weight, and blood pressure were recorded. (1) Received 20 g of garlic daily, plus 1 tablespoon lemon juice, (2) received 20 g garlic daily, (3) received 1 tablespoon of lemon juice daily, and (4) did not receive garlic or lemon juice. A study technician was done the random allocations using a random numbers table. All participants presented 3 days of dietary records and 3 days of physical activity records during 8 weeks. Blood samples were obtained at study baseline and after 8 weeks of intervention.

RESULTS

Results showed a significant decrease in total cholesterol (changes from baseline: 40.8 ± 6.1, P < 0.001), low-density lipoprotein-cholesterol (29.8 ± 2.6, P < 0.001), and fibrinogen (111.4 ± 16.1, P < 0.001) in the Group 1, in comparison with other groups. A greater reduction in systolic and diastolic blood pressure was observed in Group 1 compared with the Groups 3 and 4 (37 ± 10, P = 0.01) (24 ± 1, P = 0.02); respectively. Furthermore, a great reduction in body mass index was observed in the mixed group compared with the lemon juice and control groups (1.6 ± 0.1, P = 0.04).

CONCLUSIONS

Administration of garlic plus lemon juice resulted in an improvement in lipid levels, fibrinogen and blood pressure of patients with hyperlipidemia.

Consumption of onion juice modulates oxidative stress and attenuates the risk of bone disorders in middle-aged and post-menopausal healthy subjects

Osteoporosis is a chronic inflammatory condition that is characterized by the loss of bone mineral density (BMD).

Hypocholesterolemic Efficacy of Quercetin Rich Onion Juice in Healthy Mild Hypercholesterolemic Adults: A Pilot Study

Onion (Allium cepa L.) is widely employed as a food ingredient as well as traditional remedy to treat fever, burns, and scurvy. The present study focused on the modulator efficacy of the quercetin rich onion juice on lipid profile and antioxidant status in mildly hypercholesterolemic subjects. Twenty-four healthy subjects with mild hypercholesterolemia (≧ 200 mg/dL) were recruited and divided into two groups, and they consumed 100 mL of onion juice or placebo every day for 8 weeks. Fasting blood samples were collected at initial, 2nd, 6th, 8th, 10th week for estimating various biochemical assays, as well as anthropometric indices. After 8 weeks of intervention, onion juice greatly decreased (p < 0.05) waist circumference, total cholesterol and LDL-c. In addition, it elevates (p < 0.05) total antioxidation capacity and prolong lag-time of LDL oxidation were also noted. To conclude, drinking onion juice could markedly suppress cholesterol level and elevate total antioxidation capacity. Hence, onion juice was probably recommended for combating various cardiovascular diseases.

The effects of acute garlic supplementation on the fibrinolytic and vasoreactive response to exercise

Background

The purpose of this project was to examine the effects of acute garlic supplementation on fibrinolysis and vasoreactivity both at rest and following maximal exercise.

Methods

Eighteen healthy trained males (20.9 ± 2.2 years, 178 ± 7.7 cm, 75.5 ± 9.6 kg, VO₂max = 59.8 ± 6.7 ml • kg⁻¹ • min⁻¹) performed a graded treadmill test to volitional exhaustion. Blood samples were taken at rest, within two minutes post-exercise, and one hour post-exercise. Eleven of the subjects also had a brachial vasoreactivity test performed immediately after the blood sample to assess flow-mediated dilation (FMD) of the brachial artery. Participants were randomly assigned to ingest either 900 mg of powdered garlic or a placebo three hours before the exercise session. The supplement was distributed in a double-blind, crossover fashion. Participants repeated the protocol with the other treatment after a 14-day washout period. Paired t-tests were used to compare VO₂max between the two trials. A two-factor (treatment and time) repeated measures analysis of variance (ANOVA) was used to assess changes in FMD, tPA activity, tPA antigen, and PAI-1 activity. A priori statistical significance was set at P <0.05.

Results

VO₂max was greater for the garlic treatment trial vs. placebo (Placebo = 59.8 ± 6.7 ml • kg⁻¹ • min⁻¹; Garlic = 61.4 ± 6.6 ml • kg⁻¹ • min⁻¹). There was no main effect for treatment and no treatment x time interaction for FMD or any fibrinolytic variables examined.

Conclusion

Acute garlic supplementation does not alter vasoreactivity, fibrinolytic potential or the fibrinolytic response to exercise in young healthy trained males. Acute garlic supplementation does, however, cause a small but statistically significant increase in VO₂max. It remains unclear if this increase in VO₂max is of functional importance.

Onion (Allium cepa L.) peel extract has anti-platelet effects in rat platelets

The effects of onion peel extract (OPE) in collagen (5 μg/mL)-stimulated washed rat platelet aggregation were investigated. OPE inhibited platelet aggregation via inhibition of aggregation-inducing molecules, intracellular Ca(2+) and thromboxane A2 (TXA2) by blocking cyclooxygenase-1 (COX-1) and TXA2 synthase (TXAS) activities in a dose-dependent manner. In addition, OPE elevated the formation of cyclic adenosine monophosphate (cAMP), aggregation-inhibiting molecule, but not cyclic guanosine monophosphate (cGMP). High performance liquid chromatography (HPLC) analysis of OPE revealed that OPE contains quercetin, one of the major flavonoids, which has anti-platelet effect. In conclusion, we suggest that OPE is an effective inhibitor of collagen-stimulated platelet aggregation in vitro. Therefore, it can be a promising and safe strategy for anti-cardiovascular diseases.

A rethinking on the benefits and drawbacks of common antioxidants and a proposal to look for the antioxidants in allium products as ideal agents: a review

This review article on the beneficial uses of Allium antioxidants tries to give some answers to the recent doubts raised by Singh et al. (Ind J Clin Biochem 25(3):225-243, 2010) against the claim of some researchers that Antioxidants (AOs) are miraculous molecules. Many people still believe that vitamins like A, C and E are the only true AOs that play important role in the corrections of metabolic derangements in life style diseases and hence all their faults are attributed to the failures of AOs as a class. This is quite unfair as there are many other natural AOs that do equal or even better AO action than the vitamins. Such is the case with the Allium S-alkyl sulfoxide aminoacids and their breakdown products viz, the various poly sulfides and their oxides e.g. allicin and ajoene type compounds which trap electrons mainly. It is true that antioxidant vitamins and β-carotene a precursor of Vitamin A bring about problems as prooxidant or as agents that block some metabolic pathways and gene expression. Again the argument that AOs cannot improve the level of antioxidant enzymes like SOD, catalase and glutathione Px is also not universal. Actually allium AOs can even spare the use of antioxidant vitamins in the body and enhance the action of antioxidant enzymes and supply of ATP and other nutrients to the tissues as the former are good vasodialators and promoters of membrane permeability. The use of AOs should be selective and moderate. Allium AOs satisfy the role of ideal AOs based on many of their invivo and invitro actions reported by the author and others. Their metabolits can regenerate them and recycle them for a sufficient time in the body. They have non antioxidant effects also such as antiplatelet, fibrinolytic, antiinflammatory, immunomodulatory, antiageing actions etc. Plant derived AOs may be more beneficial and better tolerated in their partially purified forms rather than in their absolutely purified forms as the accompanying principles have some protective and regulatory effects in general. This and other aspects of allium AOs are discussed in the paper.

Echinacea purpurea and Allium sativum as immunostimulants in fish culture using Nile tilapia (Oreochromis niloticus)

The study was conducted to evaluate the efficiency of echinacea (E) and garlic (G) supplemented diets as immunostimulant for tilapia (Oreochromis niloticus). Seven treatments were designed including a control (C). Fish were fed on 35% protein diet at a rate of 3% body weight per day. Echinacea (1.0 ppt) and garlic (3%) were incorporated in the feed, which was administered for periods of 1, 2 and 3 months (summer season), followed by basal diet for 4 more months (winter season). Neutrophil adherence and haematocrit values increased in both supplemented groups with prolonging period of application. The neutrophils adherence was significantly increased in all treatments except group administered echinacea for 1 month. The lymphocytic counts were significantly (p < 0.004) elevated that resulted in a significant increase in the total leucocytic count in groups administered echinacea for 1 and 2 months when compared with the control and/or other treatments. The gain in the body weight and specific growth rate was significantly increased in all supplemented groups (p < 0.004) during summer, but remained without any significant increase after winter. The survival rate was significantly high (>85%) in all the supplemented groups. The percentage of protection, after challenge infection using pathogenic Aeromonas hydrophila was the highest in groups supplemented with echinacea and garlic for 3 months after summer and winter seasons. It could be concluded that echinacea and garlic improve the gain in body weight, survival rate and resistance against challenge infection. Both compounds showed extended effects after withdrawal and improved resistance to cold stress during the winter season. However, a full commercial cost benefit analysis is necessary before recommending their application in aquaculture.

Hypocholesterolemic activity of onion is mediated by enhancing excretion of fecal sterols in hamsters

Onion has been shown to favorably modify the lipoprotein profile. However, research on its underlying mechanism is lacking. The present study investigated the interaction of dietary onion powder with the protein expression of key receptors and enzymes involved in cholesterol metabolism. Thirty-six male hamsters were randomly divided into three groups and fed a high-cholesterol control diet or the two experimental diets supplemented with 1% onion powder (OP-1) or 5% onion powder (OP-5), for a period of 8 weeks. It was found that onion dose-dependently decreased plasma total cholesterol (TC) level. The change in plasma lipoprotein profile was accompanied by a greater excretion of both fecal neutral and acidic sterols. Western blot analysis revealed that onion up-regulated sterol regulatory element binding protein 2 (SREBP-2), liver X receptor alpha (LXRα) and cholesterol-7α-hydroxylase (CYP7A1) with no effect on 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) and LDL receptor (LDL-R). It was concluded that the hypocholesterolemic activity of onion powder was mediated by enhancement of fecal sterol excretion and up-regulation of LXRα and CYP7A1.

Alterations in the blood glucose, serum lipids and renal oxidative stress in diabetic rats by supplementation of onion (Allium cepa. Linn)

This study examined the anti-diabetic effect of onion (Allium cepa. Linn) in the streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley rats were divided into normal rats fed control diet or supplemented with onion powder (7% w/w) and diabetic rats fed control diet or supplemented with onion powder. Diabetes was induced by a single injection of STZ (60 mg/kg, ip) in citrate buffer. The animals were fed each of the experimental diet for 5 weeks. Blood glucose levels of rats supplemented with onion were lower than those of rats fed control diet in the diabetic rats. Onion also decreased the total serum lipid, triglyceride, and atherogenic index and increased HDL-cholesterol/total cholesterol ratio in the diabetic rats. Glutathione peroxidase, glutathione reductase and glutathione S-transferase activities were high in the diabetic rats compared to normal rats and reverted to near-control values by onion. These results indicate that onion decreased blood glucose, serum lipid levels and reduced renal oxidative stress in STZ-induced diabetic rats and this effect might exert the anti-diabetic effect of onion.

In vivo evidence of hepato- and reno-protective effect of garlic oil against sodium nitrite-induced oxidative stress

Sodium nitrite (NaNO2), a food color fixative and preservative, contributes to carcinogenesis. We investigated the protective role of garlic oil against NaNO2-induced abnormalities in metabolic biochemical parameters and oxidative status in male albino rats. NaNO2 treatment for a period of three months induced a significant increase in serum levels of glucose, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), bilirubin, urea and creatinine as well as hepatic AST and ALT. However, significant decrease was recorded in liver ALP activity, glycogen content, and renal urea and creatinine levels. In parallel, a significant increase in lipid peroxidation, and a decrease in glutathione content and catalase activity were observed in the liver and the kidney. However, garlic oil supplementation showed a remarkable amelioration of these abnormalities. Our data indicate that garlic is a phytoantioxidant with powerful chemopreventive properties against chemically-induced oxidative stress.

Antioxidative activity and ameliorative effects of memory impairment of sulfur-containing compounds in Allium species

The antioxidative activity and ameliorative effects on memory impairment by sulfur-containing compounds which occur in Allium vegetables such as onion and garlic were investigated. The antioxidative activities of S-alk(en)yl-L-cysteines and their sulfoxides, volatile alk(en)yl disulfides and trisulfides, and vinyldithiins were examined by using human low-density lipoprotein. It was elucidated that the alk(en)yl substituents and the number of sulfur atoms in the compounds were important for the antioxidative activities. To demonstrate the ameliorative effects on memory impairment, onion extract and synthesized di-n-propyl trisulfide were administered to senescence-accelerated mouse P8. The behavioral experiments showed that onion extract and di-n-propyl trisulfide had highly ameliorative effect of memory impairment. Furthermore, it was found that the hippocampus lipid hydroperoxide in senescence-accelerated mouse P8 was decreased by the administration of di-n-propyl trisulfide. These results suggest that di-n-propyl trisulfide contained in onion ameliorates memory impairment in SAMP8 mouse by its antioxidant effect.

The consumption of Hibiscus sabdariffa dried calyx ethanolic extract reduced lipid profile in rats

The scientific basis for the statement that plants and their active constituents play an important role in the prevention of chronic and degenerative diseases is continously advancing. The object of the present study was to evaluate the effect of Hibiscus sabdariffa L. dried calyx ethanolic extract on the serum lipid profile of Sprague-Dawley rats. The rats were fed during 4 weeks with either a basal diet, containing high cholesterol (1%), cholic acid (0.25%), lard oil (10%), or a supplemental diet with H. sabdariffa extract at 5%, 10%, and 15% levels (SD(5), SD(10), SD(15)). Weight gain and faeces dry weight were both very significantly less (p <or= 0.01) in SD(10) and SD(15) groups as compared to the control group, as was food efficiency in SD(15). In the case of SD(10), food efficiency was only significantly lower (p <or= 0.05). Faeces dry weight in SD(5) however, was the only one found to be significantly higher (p <or= 0.05). Triacylglycerols and LDL levels were both significantly less (p <or= 0.05) in all groups (SD(5), SD(10), and SD(15)) as compared to the control. For total lipids, SD(10) and SD(15) showed significantly lower levels (p <or= 0.05), whereas very significant differences (p <or= 0.01) were observed in the case of SD(5). All groups had lower cholesterol levels compared to controls; however, only the SD(5) group was statistically significant (p <or= 0.05). No significant results were found in any group in the cases of either phospholipid or HDL levels. A hypothesis of hibiscus acid racemization, (+)-HCA to (-)-HCA, mediated by intestinal flora enzymes possibly explains the significant triacylglycerol decrease in all experimental groups. VLDL, the precursor of LDL, is composed predominantly of triacylglycerols, suggesting that the significant decrease in LDL is related to observed triacylglycerol synthesis inhibition. Five percent H. sabdariffa extract addition showed the best results in the reduction of serum lipids under study conditions.

Effect of garlic (Allium sativum) on lipid peroxidation in experimental myocardial infarction in rats

The present study was conducted to elucidate the antioxidant role of garlic oil in isoproterenol (IPL)-induced myocardial infarction in rats. In myocardial necrosis induced by isoproterenol, a significant increase in serum iron content with a significant decrease in plasma iron binding capacity, ceruloplasmin activity and glutathione (GSH) level were observed. There was also a significant increase in lipid peroxides levels on isoproterenol administration. Activities of antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione-S-transferase (GST) and glutathione reductase (GRD) were decreased significantly in heart with isoproterenol-induced myocardial necrosis. Garlic oil produced a marked reversal of these metabolic changes related to myocardial infarction induced by isoproterenol. In conclusion, garlic oil exerts its effects by modulating lipid peroxidation and enhancing antioxidant and detoxifying enzyme systems.

Effects of dietary garlic on cholesterol metabolism in laying hens

Experiments were conducted to evaluate the potential for dietary garlic to influence egg yolk cholesterol concentrations and overall performance in different layer strains. Thirty-six, 28-wk-old, Hisex Brown,Isa Brown, Lohmann, Starcross, Babcock, and Starcross-579 strains (six hens per strain) were fed diets supplemented with 0 (control), 2, 4, 6, 8, or 10% sun-dried garlic paste for 6 wk. There were no differences (P > 0.05) among diets or strains in egg weight, egg mass, feed consumption, feed efficiency, and BW gain as averaged over 6 wk. Yolk weight, however, responded quadratically with increasing levels of dietary garlic and differed among strains (P < 0.05). Egg production and yolk weights were significantly higher in the Babcock strain in comparison with other strains. Serum and egg yolk cholesterol concentrations decreased linearly (P < 0.05) with increasing levels of dietary garlic. Serum and egg yolk cholesterol concentrations also differed among different strains (P < 0.05). It was concluded that garlic paste in the diets of laying hens reduced serum and yolk cholesterol concentrations. It was also concluded that dietary garlic paste had no adverse effects on layer performance.

The influence of heating on the anticancer properties of garlic

Allyl sulfur compounds are the major active constituents found in crushed garlic. Research has revealed that garlic and its lipid- or water-soluble components have many pharmacologic properties; however, studies also demonstrate that heating has a negative influence on these beneficial effects. We recently conducted several studies to investigate the influence of microwave or oven heating on the anticarcinogenesis property of garlic. Our studies showed that as little as 60 s of microwave heating or 45 min of oven heating can block garlic's ability to inhibit in vivo binding of mammary carcinogen [7,12-dimethylbenzene(a)anthracene (DMBA)] metabolites to rat mammary epithelial cell DNA. Allowing crushed garlic to "stand" for 10 min before microwave heating for 60 s prevented the total loss of anticarcinogenic activity. Our studies demonstrated that this blocking of the ability of garlic was consistent with inactivation of alliinase. These studies suggest that heating destroyed garlic's active allyl sulfur compound formation, which may relate to its anticancer properties.

A randomized trial of the effects of garlic oil upon coronary heart disease risk factors in trained male runners

Most trials of bulb garlic and garlic powder tablets indicate reduced coronary heart disease (CHD) risk in elevated-risk subjects. Most persons taking garlic supplements lack overt risk of CHD. However, no trials have tested steam-distilled garlic oil (GO) capsules with healthy subjects. The objectives of the present randomized, double-blind, placebo-controlled study were to determine whether GO capsules reduce CHD risk in trained male runners. Twenty-seven volunteers (mean age, 28.8 years) completed the study. Each took 12.3 mg/day GO (or placebo) capsules for 16 weeks. Main outcome measures were 95% confidence intervals (CIs) between GO and placebo groups for differences in changes of blood pressure (BP), plasma lipids, total antioxidant status (TAS), low-density lipoprotein (LDL) composition and blood clotting factors. Principal results as mean differences (95% CI) between GO and placebo are: pulse, 2.9 beats/min (-0.8 to 6.7), P = 0.12; systolic BP, -4.5 mmHg (-10.8 to 1.9), P = 0.16; plasma total cholesterol, 0.01 mmol/l (-0.34 to 0.37), P = 0.95; plasma triglycerides, -0.20 mmol/l (-0.43 to 0.03), P = 0.09; plasma TAS, 45 micromol Trolox equivalent/l (-35 to 124), P = 0.26; LDL density, 0.0019 g/ml (-0.0005 to 0.0043), P = 0.12; LDL triglycerides/protein, -0.078 mg/mg (-0.149 to -0.007), P = 0.03; LDL cholesterol/protein, -0.24 mg/mg (-0.69 to 0.22), P = 0.3; LDL TAS/triglycerides, 29 nmol/mg (11, 68), P = 0.15; prothrombin time, 0.99 s (-0.36 to 2.35), P = 0.14; partial thromboplastin time, 3.0 s (-1.0 to 7.1), P = 0.13. Results were null statistically. Trends with GO were mostly towards lower CHD risk, and a larger study (approximately 150 subjects) is required to test their validity.

Immunomodulatory effect of some naturally occuring sulphur-containing compounds

The immunomodulatory effects of naturally occurring sulphur compounds such as diallyl sulphide (DAS), diallyl disulphide (DADS) and allyl methyl sulphide (AMS) were studied in BALB/c mice. After treatment with five doses (20 mg/dose) of sulphur-containing compounds, the total white blood cell (WBC) count was enhanced significantly in mice. Among the sulphur compounds studied, DADS showed the maximum number of WBC (17,900 cells/mm(3)) on the 6th day, and highest antibody titre of 516 on the 12th day. Administration of DAS and DADS enhanced the weight of vital organs such as the spleen and thymus. DADS, AMS, and DAS administration could enhance the number of plaque forming cells (PFC) in the spleen of the animals. Maximum numbers of PFC (1,409 PFC/10(6) spleen cells) were observed in DADS-treated animals. Bone-marrow cellularity was also increased significantly (P<0.001) in DADS (19.3 x 10(6) cells/femur) and AMS (24.7 x 10(6) cells/femur) treated animals. The number of alpha-esterase positive cells was enhanced in DAS (1,315/4,000 cells), DADS (1,748/4,000 cells), and AMS (1,648/4,000 cells) treated animals, compared to normal animals (1,065/4,000 cells). These results are suggestive of an immunostimulating effect of sulphur compounds.

Antioxidant effect of onion oil (Allium cepa. Linn) on the damages induced by nicotine in rats as compared to alpha-tocopherol

The beneficial effects of onion oil as an antioxidant has been assessed in nicotine administered rats by studying whether the peroxidative damage caused by nicotine can be effectively combated with the onion oil and the effects compared to vitamin E, a highly efficient antioxidant. Lipid peroxidation products and antioxidant defence system have been studied in liver, lungs, and heart. The rats were injected with nicotine (0.6 mg/kg body wt.) and simultaneously given onion oil (100 mg/kg body wt.) or vitamin E (100 mg/kg body wt.) for 21 days. Concentration of free fatty acids, TBA reactive substances (TBARS), conjugated dienes and hydroperoxides were significantly increased in the tissues of nicotine treated rats as compared to normal rats. Onion oil supplemented to nicotine treated rats showed increased resistance to lipid peroxidation and the effect was near to that of vitamin E fed rats. The activity of catalase and superoxide dismutase decreased in nicotine treated rats. Antioxidants-glutathione content, vitamin C and retinol showed no significant difference but liver vitamin E content significantly decreased in nicotine treated rats. On onion oil or vitamin E supplementation, the concentration of antioxidants were significantly raised in all the tissues studied, however, a significantly increased concentration of glutathione, vitamin E and retinol was noticed in vitamin E+nicotine treated rats. Thus, these results indicate that onion oil is an effective antioxidant against the oxidative damage caused by nicotine as compared to vitamin E.

Heating garlic inhibits its ability to suppress 7, 12-dimethylbenz(a)anthracene-induced DNA adduct formation in rat mammary tissue

The present studies compared the impact of heating, either by microwave or convection oven, on the ability of garlic to reduce the in vivo bioactivation of 7,12-dimethylbenz(a)anthracene (DMBA) in 55-d-old female Sprague-Dawley rats. In study 1, rats were fed a semipurified casein-based diet and treated by gastric gavage thrice weekly for 2-wk with crushed garlic (0.7 g in 2 mL corn oil) or the carrier prior to DMBA treatment (50 mg/kg body weight). Providing crushed garlic reduced by 64% (P < 0.05) the quantity DMBA-induced DNA adducts present in mammary epithelial cells compared to controls. In study 2, microwave treatment for 60 s, but not 30 s, decreased (P < 0.05) the protection provided by garlic against DMBA-induced adduct formation. In study 3, allowing crushed garlic to stand for 10 min prior to microwave heating for 60 s significantly (P < 0.05) restored its anticarcinogenic activity. Microwave heating of garlic for 30 s resulted in a 90% loss of alliinase activity. Heating in a convection oven (study 4) also completely blocked the ability of uncrushed garlic to retard DMBA bioactivation. Study 5 revealed that providing either 0.105 micromol diallyl disulfide or S-allyl cysteine by gastric gavage thrice weekly for 2 wk was effective in retarding DMBA bioactivation but isomolar alliin was not. These studies provide evidence that alliinase may be important for the formation of allyl sulfur compounds that contribute to a depression in DMBA metabolism and bioactivation.

Effects of aqueous extract of onion on the liver and lung of rats

The toxic effects of oral and intraperitoneal administration of onion extracts on lung and liver tissue of rats were investigated. Oral or intraperitoneal administration of low doses of onion (50 mg/kg) to rats had little effect on lung and liver tissues when compared to control animals. In contrast, administration of high doses of onion (500 mg/kg) resulted in apparent histological changes in lung and liver tissues of rats. Intraperitoneal administration of the high dose of onion was more damaging to lung and liver tissue than oral administration and resulted in a 25% rate of mortality in this treatment group. These results suggest that low doses of onion are nontoxic and may be administered with few ill effects.

Clinical trials of herbs

Consumers, clinicians, and corporations are taking an interest in botanical medicine. Although large gaps remain in research, many clinical trials of herbs exist. This article reviews these trials.

Modulation of cholesterol levels in broiler meat by dietary garlic and copper

Male Ross x Ross 208 chickens were fed from hatching to 21 d of age either a control diet (based on corn and soybean meal) or the control diet supplemented with 0, 1.5, 3.0, and 4.5% of a commercial garlic powder in Experiments 1 and 2. Once the dose-response relationship was established, 3% garlic powder or 63 or 180 mg/kg copper as cupric citrate or cupric sulfate pentahydrate were supplemented to the diet (Experiments 3, 4, 5, and 6). In the first two experiments, reductions of plasma cholesterol (P = 0.006) and triacylglycerols (P = 0.013) and liver (P = 0.012) and breast muscle (P = 0.165) cholesterol were observed in garlic-supplemented birds. Feeding either garlic powder or copper (63 and 180 mg/kg) resulted in reduced levels of plasma cholesterol, liver cholesterol, blood reduced glutathione, and breast and thigh muscle cholesterol. Differences were significant at P < 0.05 in at least one experiment. 3-Hydroxy-3-methylglutaryl reductase activity was decreased due to dietary garlic (P = 0.0369), but not by pharmacological levels of dietary copper (P = 0.982). The activity of fatty acid synthetase was decreased in birds fed copper (P = 0.035). Both garlic and copper supplements decreased cholesterol 7 alpha-hydroxylase activity (P = 0.024 and P = 0.022, respectively). The results of these trials confirm the findings that garlic and copper alter lipid and cholesterol metabolism. However, they do not work by the same mechanism. Feeding dietary garlic or copper for 21 d reduced cholesterol levels of broiler meat without altering growth of the chickens or feed efficiency.

Effects of garlic on atherosclerosis

This review discusses the use of garlic and garlic preparations as agents for prevention and treatment of atherosclerosis and atherosclerosis-related diseases. Garlic indirectly effects atherosclerosis by reduction of hyperlipidemia, hypertension, and probably diabetes mellitus and prevents thrombus formation. In addition, in animal models, garlic causes direct antiatherogenic (preventive) and antiatherosclerotic (causing regression) effects at the level of artery wall. Garlic's direct effect on atherosclerosis may be explained by its capacity to reduce lipid content in arterial cells and to prevent intracellular lipid accumulation. This effect, in turn, is accompanied by other atherosclerotic manifestations, i.e., stimulation of cell proliferation and extracellular matrix synthesis. Clinical trials are currently being carried out to reveal the possible effect of garlic therapy on human atherosclerosis. Positive results of these trials may open a new era in the use of garlic for prevention and treatment of many atherosclerosis-related diseases.