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Therapeutic effects of garlic clarified: Antimicrobial allicin

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Allicin from garlic fights infection by its antimicrobial properties that can disable a wide variety of infectious organisms. Scientists found out how garlic in moderation works for health benefits, according to the study, "Allicin from garlic strongly inhibits cysteine proteinases and cytopathic effects of Entamoeba histolytica," published in the October 1997 issue of the journal Antimicrobial Agents and Chemotherapy.

The allicin in the garlic is created when garlic cloves are crushed. It's that allicin protecting the garlic plant from soil parasites and fungi. Allicin also is also responsible for garlic's pungent smell.

Back in 1997, two studies conducted at the Weizmann Institute of Science uncovered a molecular mechanism which may be the basis for some of garlic's therapeutic effects

For example, allicin from garlic disables dysentery-causing amoebas by blocking two groups of enzymes known as cysteine proteinases and alcohol dehydrogenases. The researchers were able to study how garlic works at the molecular level thanks to their unique biotechnological procedure for producing large quantities of pure allicin, garlic's main biologically active component.

One study, appearing in the October 1997 issue of the American Society for Microbiology's Antimicrobial Agents and Chemotherapy, explains how allicin fights infection. This research supports the notion that garlic is an excellent, although smelly, natural antimicrobial drug that can disable an unusually wide variety of infectious organisms.

The second study, reported in Biochimica Biophysica Acta, may help clarify the role allicin plays in preventing heart disease and other disorders

In the studies, the scientists revealed and characterized a molecular mechanism by which allicin blocks certain groups of enzymes. Allicin, created when garlic cloves are crushed, protects the plant from soil parasites and fungi and is also responsible for garlic's pungent smell.

The studies were led by Profs. David Mirelman and Meir Wilchek of the Institute's Biological Chemistry Department, who worked together with departmental colleagues Drs. Serge Ankri, Talia Miron and Aharon Rabinkov and with Prof. Lev Weiner and Dr. Leonid Konstantinovski of the Organic Chemistry Department.

A natural weapon against infection

The research reported in the October 1997 issue of Antimicrobial Agents and Chemotherapy, revealed that allicin disables dysentery-causing amoebas by blocking two groups of enzymes, cysteine proteinases and alcohol dehydrogenases. Cysteine proteinase enzymes are among the main culprits in infection, providing infectious organisms with the means to damage and invade tissues. Alcohol dehydrogenase enzymes play a major role in these harmful organisms' metabolism and survival.

Because these groups of enzymes are found in a wide variety of infectious organisms such as bacteria, fungi and viruses, this research provides a scientific basis for the notion that allicin is a broad-spectrum antimicrobial drug, capable of warding off different types of infections.

"It has long been argued that garlic can fight a wide range of infections, and now we have provided biochemical evidence for this claim," says Prof. Mirelman, in an October 14, 1997 news release, "Therapeutic Effects of Garlic Clarified by Weizmann Institute Research."

Garlic is believed to work wonders, from fighting disease to keeping away vampires. The role of allicin in warding off infection may be particularly valuable in light of the growing bacterial resistance to antibiotics. It is unlikely that bacteria would develop resistance to allicin because this would require modifying the very enzymes that make their activity possible.

Mechanism explained: How allicin blocks certain enzymes and may prevent the production of artery-clogging cholesterol, but scientists need to find out the role played by garlic

In the study that appeared in Biochimica Biophysica Acta, the Institute scientists found that allicin blocks the enzymes by reacting with one of their important components known as sulfhydryl (SH) groups, or thiols.
This finding has important implications because sulfhydryl groups are also crucial components of some enzymes that participate in the synthesis of cholesterol. By reacting with and modifying the sulfhydryl groups in those enzymes, allicin may prevent the production of artery-clogging cholesterol.

"It has been suggested that garlic lowers the levels of harmful cholesterol, and our study provides a possible explanation for how this may occur," says Professor Wilchek in the news release. "However, more research is necessary to establish what role allicin might play in preventing the clogging up of arteries."

Complicating the issue is the concern that blocking sulfhydryl groups in proteins may sometimes be harmful because these groups are also present in enzymes involved in some of the body's vital processes. However, unlike most bacteria, human tissue cells contain detoxifying molecules of a substance called glutathione, which helps maintain appropriate sulfhydryl levels. These glutathione molecules can reverse the anti-sulfhydryl effects of small amounts of allicin.

Measuring antioxidant activity

While reaction with sulfhydryl groups appears to explain most of allicin's activity, it has also been suggested that allicin acts as an antioxidant. The study reported in BBA confirmed this antioxidant effect and for the first time provided its quantitative assessment. Antioxidants gobble up harmful free radicals believed to contribute to tumor growth, atherosclerosis, aging and other processes.

Producing pure allicin in large quantities

In nature, allicin is created when garlic cloves are cut into or crushed. The cutting or crushing causes two components of garlic, alliin and the enzyme alliinase, to interact.

The allicin produced at the Weizmann Institute is semi-synthetic; first, its precursor, alliin, is chemically synthesized, then a modified form of the natural enzyme, alliinase, converts it into pure allicin.The pure semi-synthetic allicin can be stored for months without losing its effectiveness.

In contrast, the natural compound loses its beneficial properties within hours because it begins to react with garlic's other components as soon as the clove is crushed

A patent application for this production of pure allicin has been submitted by Yeda Research and Development Co., the Institute's technology transfer arm, and several companies have already expressed interest in scaling up the process for commercial use and clinical testing, at the date of the 1997 press release.
Prof. Mirelman, the Weizmann Institute's Vice President for Technology Transfer, holds the Besen-Brender Chair of Microbiology and Parasitology, and Professor Wilchek, Dean of the Biochemistry Faculty, holds the Marc R. Gutwirth Chair of Molecular Biology.

This research was funded in part by the Center for Molecular Biology of Tropical Diseases at the Weizmann Institute and the Avicenne Program of the European Union. Drs. Rabinkov and Konstantinovski were partly supported by the Center for the Absorption of Scientists of Israel's Ministry of Absorption.

Garlic sometimes can be sniffed on someone at a distance of several feet

What is it about other smelly foods that are not spoiled, but smell that way when safe to eat in moderation that gives some foods? To some people cheese smells like sweaty socks. The alcohol you drink comes out of your pores. It may be about how your nose and brain perceive odors you don't consume with foods frequently. Examples might be garlic and Limburger Cheese cheese on bread. Check out the site, "Top 10 Stinky Cheeses in the World - HotelClub."

Some foods do have antimicrobial properties but are not so smelly. Other foods have strong scents and are antimicrobial in some ways, such as oregano as a seasoning or curry powder. There's also aromatic foods in varying degrees from mild olive oil to fragrant cloves. But extracts of pleasant-smelling coconut also have some antimicrobial properties as do various herbs and spices in differing degrees such as peppermint oil put into toothpaste and on dental floss.

Do smelly but not rotten foods in general have antimicrobial properties?

Some people who have been vegan for many decades can actually smell the breath of a cheese and meat-eater and classify the odor as if the person is rotting or fermenting or perceive the odor as sweaty socks or ripe old sneakers left in the rain to breed bacteria. Some people who cringe at the scent of alcohol may perceive alcohol as a stench that oozes out of your pores, not only your breath.

Breastfeeding women usually have the flavor of what foods they ate change the taste of their breast milk. The baby will be able to taste the strong garlic you ate or the vanilla, mint, or carrots. Chocolate you ate may give your baby diarrhea.

Also, your prenatal diet—if it regularly includes strong spices such as curry, cumin or fenugreek—may affect your newborn’s body odor. Some newborn babies smell like the spices and herbs the mother ate while pregnant, particularly the smell of strong spices. For example, people first smelling cumin may describe it as a strong odor of sweat or smelling like sweaty socks.

Alcohol is metabolized in the liver into acetic acid. If you drink often, the smell of alcohol also comes out in sweat and can be smelled on the skin as it's released through the pores and not only on your breath. Check out the study, "The effect of meat consumption on body odor attractiveness." Authors are Havlicek J, and Lenochova P. The study is published in the journal Chemical Senses. October 31, 2006. Published online since August 4, 2006.

Eating excess meats frequently can cause body odor. In a small study published in the journal Chemical Senses in 2006, women rated men's body odors (taken from their armpits) as more attractive and pleasant and less intense when the men ate no meat for two weeks, compared to when they consumed red meat. See the study, "The effect of meat consumption on body odor attractiveness," Chemical Senses, 2006. Authors are Jan Havlicek1 and Pavlina Lenochova2

The study is within a special edition, "Special Issue: What's in a Sniff?: The Contributions of Odorant Sampling to Olfaction," Volume 31 Issue 2 February 2006. Persons who didn't eat meat were perceived as stinking less than those who did eat meat. In the study, researchers looked at axillary body odor, which is individually specific and potentially a rich source of information about its producer.

Odor individuality partly results from genetic individuality, but the influence of ecological factors such as eating habits are another main source of odor variability. Researchers know very little about how particular dietary components shape our body odor. In this study, scientists tested the effect of red meat consumption on body odor attractiveness.

Non-meat eaters were judged as more pleasant, attractive, and less intense

In the study, 17 male odor donors were on “meat” or “non-meat” diet for 2 weeks wearing axillary pads to collect body odor during the final 24 hours of the diet. Fresh odor samples were assessed for their pleasantness, attractiveness, masculinity, and intensity by 30 women not using hormonal contraceptives.

Scientists repeated the same procedure a month later with the same odor donors, each on the opposite diet than before. Results of repeated measures analysis of variance showed that the odor of donors when on the non-meat diet was judged as significantly more attractive, more pleasant, and less intense. This suggests that red meat consumption has a negative impact on perceived body odor hedonicity. When the capacity of human observers to remember incidentally learned olfactory sensations as a function of their perceived pleasure/ displeasure is investigated, researchers refer to this process as hedonicity.

When mosquitoes get close to a person they make a decision on whether they bite or not based on essentially the smell of our skin, and that smell can vary from person to person because of different combinations of chemicals on the skin.

Female mosquitoes are primarily attracted to our body heat and the carbon dioxide we breathe out, which indicate we are warm-blooded animals with the blood they need to develop fertile eggs. So the more carbon dioxide we emit, the more attractive we are to females looking for a protein hit. (Male mosquitoes don't bite), according to the article, "Are some people more attractive to mosquitoes? - Health & Wellbeing."

Larger people tend to emit more carbon dioxide than smaller people, as do pregnant women and those who exert themselves. This is why we are often annoyed most by mosquitoes after we play sports and are breathing heavily. Mosquitoes are also attracted to different chemicals on our skin.

But what we eat can also play a role—which is why researchers who do studies on human body odors routinely tell their subjects to avoid foods thought to affect the results. If you have good hygiene but find that you have an unpleasant odor (or other people tell you so), you might see whether anything in your diet is contributing to the problem. Research on how foods affect body odor is limited.

Do vegans smell better?

Some vegetables cause specific body odors. Yet meat-eaters are perceived as smelling worse than non-meat eaters in a recent study. According to the article, "Do vegetarians smell better? - Vegetarian Food," vegans do smell better. But some vegetables can make you stink.

Also people tend to think that young people smell sweeter than old people, according to the study, "The smell of age: perception and discrimination of body odors of different ages." [PLoS One. May 30, 2012]. Authors are Mitro S, Gordon AR, Olsson MJ, and Lundström JN. Some people perceive older persons to smell worse from the foods they eat than younger people.

Babies are perceived as smelling sweet and fresh, regardless of the type of foods they eat. And some people assume older adults don't use deodorant. For example, extra virgin unheated and unprocessed organic coconut oil rubbed into armpits works well to get rid of odor without harsh chemicals absorbed by the skin, by people of any age.

When children's body odor attracts the attention of teachers

Children after the age of eight or nine are said to smell so bad, that they need a deodorant, say some teachers sniffing the body odor of exercising kids, particularly females who begin puberty as early as nine. So why are older people said to stink more than kids? One reason is because some people perceive older adults as not able to bathe frequently due to lower mobility, being too busy, or feeling colder, more frail, or anxious when bathing.

Our natural body odor goes through several stages of age-dependent changes in chemical composition as we grow older. Similar changes have been reported for several animal species and are thought to facilitate age discrimination of an individual based on body odors, alone. Researchers sought to determine whether humans are able to discriminate between body odor of humans of different ages.

Some teachers complain their second grade class has children who "stink from the nose." They might advise parents to have the kid's adenoids and tonsils removed. Other teachers notice armpit stench from nine-year old kids, particularly girls beginning early puberty. Worse is when young or middle aged-people complain that old people smell bad.

In a recent study, body odors were sampled from three distinct age groups: Young (20-30 years old), Middle-age (45-55), and Old-age (75-95) individuals. Perceptual ratings and age discrimination performance were assessed in 41 young participants. There were significant differences in ratings of both intensity and pleasantness, where body odors from the Old-age group were rated as less intense and less unpleasant than body odors originating from Young and Middle-age donors.

Participants in a recent study, "The smell of age: perception and discrimination of body odors of different ages," were able to discriminate between age categories, with body odor from old-age donors mediating the effect also after removing variance explained by intensity differences. Similarly, participants were able to correctly assign age labels to body odors originating from old-age donors but not to body odors originating from other age groups. This experiment suggests that, akin to other animals, humans are able to discriminate age based on body odor alone and that this effect is mediated mainly by body odors emitted by individuals of old age.

Foods that could make you stink at any age: It's the trimethylaminuria

If you have a specific gene for the metabolic disorder trimethylaminuria develop, you develop the odor of raw fish eminating from your orifices and pores, including your mouth each time you eat high-protein foods, especially animal protein such as fish. This is due to an inability to break down a food-derived compound (trimethylamine), which then builds up in the body and is released in sweat, breath and urine. Though the disorder is rare, the authors of a 2007 paper in the Annals of the New York Academy of Sciences found that many people with unexplained body odor tested positive for it.

Some people perceive body odor on others more than other people can. It depends on what smells you can pick up and discern as being related to the foods a person ate such as cabbage, garlic, beans, asparagus, or meats versus vegetables and fruit. See, the abstract of the study, "Identification of unpleasant odors is independent of age."

Specific vegetables also can give you body odor

The foods that cause the most body odor also may be the healthiest foods. Or they can be some of the high animal protein foods familiar to prehistoric people. The effects of foods are the odor they cause, according to the Berkeley Wellness.com article, "Can Foods Cause Body Odor?"

Other people have inherited a gene that makes their urine smell like fermenting cabbage whenever they eat asparagus. In a 2011 study from the University of South Florida and Monell Chemical Senses Center, researchers confirmed that people differ both in their ability to produce the odor and in their ability to perceive it, due to genetic variations. This is certainly no reason to stop eating asparagus. No one but you is likely to notice the strong urine smell, unless you're sharing a room with someone and the room fills up with the odor of strong-smelling, almost chemical-scented urine, as if there were a number of vegetables cooking in a pot.

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