Onions and garlic are toxic to cats, dogs & other animals; cause hemolytic anemia

Summary 

Onions and garlic contain toxic components that damage red blood cells and provoke hemolytic anemia, perhaps, even in humans (although, the study below mainly talks onions, garlic, shallots, leeks affecting cats, dogs, cattle, water buffaloes, sheep and horses.)

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Abstract

Allium species toxicosis is reported worldwide in several animal species, and the toxic principles present in them causes the transformation of hemoglobin into methemoglobin, consequently resulting in hemolytic anemia with Heinz body formation.

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The genus Allium includes onion, garlic, leek, chives, shallots, and scallions, and was previously classified in the family Alliaceae

Onion toxicosis is consistently noted in animals that ingest more than 0.5% of their body weight in onions at one time. A relatively high dose (600-800 g) in one meal or spread apart over a few days can damage red blood cells and cause hemolytic anemia accompanied by the formation of Heinz bodies in erythrocytes.(Hemolytic anemia (HEE-moh-lit-ick uh-NEE-me-uh) is a condition in which red blood cells are destroyed and removed from the bloodstream before their normal lifespan is over.
In general, signs of anemia (pallor, fatigue, shortness of breath, and potential for heart failure) are present.)

(Certain aspects of the medical history can suggest a cause for hemolysis, such as drugs (paracetamol), consumption of fava beans due to Favism, the presence of prosthetic heart valve, or other medical illness.

Domestic species that are more commonly involved in poisoning are onion (Allium cepa), garlic (Allium sativum), leek (Allium porum), and chives (Allium schoenoprasum).

Onions contain toxic components that may damage red blood cells and provoke hemolytic anemia accompanied by the formation of Heinz bodies in erythrocytes of animals such as cattle, water buffaloes, sheep, horses, dogs, and cats.

Heinz bodies can also be found in chronic liver disease.

In veterinary medicine, Heinz bodies are associated with the consumption of paracetamol (acetaminophen), garlic, and onions by cats, dogs, and various primates. Thiosulfate compounds in the flesh of onions have been identified as the cause.
(https://en.wikipedia.org/wiki/Heinz_body)

Plant poisoning is not an unusual disease in dogs and cats, since plants are not a common compound of their diet. However, they often cause acute life-threatening conditions and represent an imminent cause of death in those animals.

TOXICITY

Allium species contain various organosulfoxides, particularly alk(en)yl cysteine sulfoxides, some of which are responsible for their characteristic odor. Plant trauma (e.g. chewing or cutting) converts the organosulfoxides to a complex mixture of sulfur-containing organic compounds that are responsible for the flavor and effects of these plants on animals. Many Allium organosulfur compounds appear to be readily absorbed through the gastrointestinal tract and are metabolized to highly reactive oxidants.

Di-propyl-disulfide (H7C3S2C3H7) and allyl propylisulfide (H5C3S2C3H7) have been implicated in onion-induced hemolytic anemia. However, recently, more active oxidizing sulfur-containing compounds have been discovered and proposed as causative agents, either in onion or garlic poisoning episodes. Sodium n-propylthiosulfate, isolated from boiled onions, was proven to cause an increase of Heinz body formation in erythrocytes and subsequent hemolytic anemia in dogs.

Garlic, on the other hand, is considered to be less toxic and safe for dogs than onion when used in moderation

ACTION MECHANISM

The primary toxicological mechanism of Allium-derived organosulfur compounds is oxidative hemolysis, which occurs when the concentration of oxidants in the erythrocyte exceeds the capacity of the antioxidant metabolic pathways. Catalase antioxidant activity in dog erythrocytes is low, and normal hemoglobin in cats is about two to three times more susceptible to oxidative damage than the hemoglobin in other species (38, 39).

N-propyl disulûde and sodium n-propylthiosulfate are very poisonous organosulfur compounds present in onions. The former may cause a marked decrease in the activity of glucose-6-phosphate dehydrogenase (G6PD), whereas the latter can increase the methemoglobin concentration and Heinz body count in erythrocytes, and reduce glutathione concentration in the erythrocyte (30, 40, 41). In erythrocytes, G6PD oxidizes glutathione to a reduced form through the pentose phosphate pathway (39, 42, 43). When the activity of G6PD is decreased, the content of glutathione also drops, leading to increased levels of hydrogen peroxide. It is known that lipid peroxidation can be determined by malondialdehyde formation (44). Consequently, hydrogen peroxide and malondialdehyde oxidize the sulfhydryl groups of hemoglobin, resulting in the denaturation of hemoglobin (30).

Additionally, oxidation of the exposed β-93 cysteine residues present in hemoglobin results in sulfhemoglobin formation (45). Sulfhemoglobin and denatured hemoglobin are less soluble than normal hemoglobin, so they precipitate, aggregate, and bind to the cell membrane and form Heinz bodies. Other types of oxidation of hemoglobin globin chains result in membrane cross-linking reactions and eccentrocyte formation (46). The formation of Heinz bodies and eccentrocytes increases erythrocyte fragility and extravascular hemolysis, since erythrocytes that contain Heinz bodies are removed from the circulation by the reticuloendothelial system, thus causing anemia. Damaged erythrocytes are removed from circulation, causing hemoglobinemia and hemoglobinuria (6, 47).

Direct oxidative damage to the erythrocyte cell membrane and its sodium-potassium pump or the oxidative production of hemin also contribute to cell lysis. Oxidation of the heme ion and associated methemoglobinemia result in a left shift of the hemoglobin-oxygen dissociation curve, decreased blood oxygen transportation capacity, and, ultimately, impaired delivery of oxygen to tissues (48, 49).

Thus, the result of the oxidative hemolytic process induced by Allium consumption is the onset of anemia, methemoglobinemia, and impaired oxygen transportation. Although marked Heinz body formation may be present within a day after onions are ingested, the anemic nadir typically develops several days later (49).

Allicin and ajoene, pharmacologically active agents in garlic, are potent cardiac and smooth muscle relaxants, vasodilators, and hypotensive agents (50-52). Also, ajoene and other organosulfur compounds derived from onions are potent antithrombotic agents (53). Thus, hypotensive and antithrombotic properties can exacerbate the physiologic effects of anemia and impaired oxygen transportation. Garlic preparations that have not been aged cause direct damage to the gastric and ileal mucosa, resulting in pain and diarrhea (54).



EXPOSURE AND SUSCEPTIBILITY

Allium toxicosis commonly occurs after ingestion. In addition to consuming fresh plant material, juice, fresh and dietary supplements, powdered cooking preparations, dehydrated material, or food preparations derived from or containing Allium species can be potentially toxic to dogs and cats (37, 49). This type of toxicosis is typically caused by consumption of a single large quantity of plant material or repeated small amounts. Dogs and cats are highly susceptible to onion toxicosis, consumption of as little as 5 g/kg of onions for cats or 15 to 30 g/kg for dogs resulted in clinically important hematologic changes. Onion toxicosis is consistently noted in animals that ingest more than 0.5% of their body weight in onions at one time (49). A relatively high dose (600-800 g) in one meal or spread apart over a few days can damage red blood cells and cause hemolytic anemia accompanied by the formation of Heinz bodies in erythrocytes (37).

Dogs with hereditary high erythrocyte reduced glutathione and circulating potassium level are more susceptible to the hematologic effects of onions (36, 55). This trait is relatively common in Japanese breeds, such as Akita inu and Shiba inu. Other inborn errors in metabolism or nutritional deficiencies that result in decreased erythrocyte antioxidant defenses, such as glucose-6-phosphate dehydrogenase deficiency or zinc deficiency, could increase an animal's susceptibility to Allium toxicosis (56).

The oral administration of 500 μmol per kilogram of body weight of sodium n-propylthiosulfate to dogs results in hemolytic anemia associated with increased Heinz body formation in erythrocytes, which is more severe in dogs with the hereditary condition, which, in turns, results in erythrocytes with high concentrations of reduced glutathione and potassium than in normal dogs. In affected dogs there is a ten-fold increase in the concentration of oxidized glutathione in their erythrocytes 12 hours after the administration of the compound, whereas in normal dogs there is almost no change (36).

Humans are the most resistant species studied. On the other hand, there is some concern about the susceptibility of certain ethnic groups that have a genetic deficiency of glucose-6-phosphate dehydrogenase. Although dogs appear to be one of the most susceptible species, there are a few reports in the literature concerning accidental canine poisoning associated with onion ingestion.

Cats are more susceptible than dogs. Since baby food is often offered to sick animals that are not eating (to stimulate their appetite), there is some concern that the onion powder would cause a Heinz body anemia in these cats (57). Several baby food manufacturers add onions or onion powder to increase palatability.

It is generally accepted that sheep, goats, rats and mice are more resistant to onion toxicosis than other domestic animals (27, 48). The safety of feeding onions to livestock depends upon animal susceptibility and the toxic potential of the plant species. Sheep can be maintained on diets of up to 50% onions with no clinical abnormalities or detrimental effects on growth. Even when onions are fed free choice, sheep have only transient hemoglobinuria and anemia, with few deaths reported. In contrast, cattle should be fed onions with caution, due to the relative susceptibility of their erythrocytes to oxidative damage. Daily feeding of onions could have a cumulative effect due to ongoing formation of Heinz bodies versus a single exposure with a wide gap until the next exposure, allowing the bone marrow to regenerate the prematurely destroyed red cells (37).

Concurrent treatment with xenobiotics, drugs, or dietary factors that induce erythrocyte oxidative injury (e.g. propofol, propylene glycol, dl-methionine, sulfonamides, sulfapyridine, large doses of vitamin K3, benzocaine) or diminish erythrocyte oxidative defenses (e.g. acetaminophen) is likely to increase an animal's susceptibility to Allium species toxicosis (49).



CLINICAL SIGNS

In dogs and cats, clinical signs of Allium species toxicosis may appear within one day of consumption if large amounts of material have been ingested. However, it is more common the development of clinical signs after a lag of several days (49). The first signs are usually of gastroenteritis: vomiting, diarrhea, abdominal pain, loss of appetite, depression and dehydration. It will take a few days for the dog to display the signs associated with the loss of red blood cells: pale mucous membranes, rapid respiratory rate, difficulty to breathe, lethargy, dark colored urine (reddish or brown), jaundice, weakness, and rapid heart rate (37). Depression, hemosiderin in urine, exercise intolerance and cold sensitivity may also be observed (49). In cases of recent ingestion, the breath of the affected dog or cat may smell like onions or garlic (16).

 CLINICAL PATHOLOGY

Clinical pathology findings are consistent with intravascular and extravascular hemolysis, anemia, hemoglobinemia, hemoglobinuria associated with hemoglobin casts in urine and hemosiderin, hyperbilirubinemia, methemoglobinemia, and, if the animal survives long enough, an accompanying regenerative response (49). Hematologic tests may reveal neutrophilia, lymphopenia, Heinz-body anemia and methemoglobinamia (37).

Heinz body formation, eccentrocytosis, and a decrease in erythrocyte glutathione levels can also be detected. Additionally, eccentrocytosis appear to be one of the major diagnostic features of garlic-induced hemolysis in dogs (20, 46).

 ANATOMIC PATHOLOGY

Necropsy and histological findings typically indicate hemolytic anemia. Because of the lag of several days between ingestion and the development of clinical signs, gastrointestinal erosion or Allium in the gut content may not be seen (49). Necropsy findings basically consists of splenomegaly due to hemosiderosis and increased hemocatheresis, and jaundice due to the hemolytic anemia provoked, in turn, by extravascular hemolysis (19, 58, 59).

Histopathologic findings, although consistent with hemolytic anemia, are not specific for Allium toxicosis and may include deposition of hemosiderin in the phagocytic cells of the liver, spleen, and renal tubular epithelium; renal tubular pigment necrosis; and nephrotubular casts and hemoglobin casts in the renal tubules (58, 59).

DIFFERENTIAL DIAGNOSES

Heinz bodies comprise an uncommon finding in dogs that can only be induced by a few other toxicoses, such as methilen blue, acetaminophen, benzocaine, vitamin K3, zinc and phenylhidrazine (32, 60, 61). In such cases, Allium toxicosis should always be included in the differential diagnosis (34).

Common feline disorders associated with Heinz body formation include diabetes mellitus, particularly if ketoacidosis is present; hepatic lipidosis, hyperthyroidism; and neoplasms such as lymphoma (49). Jaundice-causing infections such as babesiosis and leptospirosis should also be included in the differentials. Additionally, post-hepatic obstructions should also be speculated due to its jaundice-causing effects.

TREATMENT

No specific antidote is available for Allium toxicosis; however, supportive care may be helpful including hospitalization, administration of intravenous fluids and blood transfusions. Treatment is indicated after ingestion of any quantity (37). Several therapeutic approaches have been suggested to treat onion-poisoned animals, including gastrointestinal decontamination, administration of antioxidant vitamins (C and E) (in dogs, ascorbic acid - 30 mg/kg of body weight intravenously, each 6 to 8 hours) or N-acetyl-cysteine, and intravenous fluid therapy or blood transfusions, but none has proven really effective (31, 34, 62). Nevertheless, even taking into account that lethal effects are infrequent in dogs, avoiding animal exposure to any kind of onion seems to be the best preventive health strategy (15, 31, 34).

Induction of emesis (e.g. apomorphine 0.08 mg/kg intramuscularly or subcutaneously, or 3% hydrogen peroxidase 2 mL/kg, no more than 45 mL) can be valuable in asymptomatic dogs and cats that showed no complicating factors one or two hours after the ingestion. Administration of activated charcoal (1 to 4 g/kg per oral) is indicated after emesis. In severely affected animals, a blood transfusion and supplemental oxygen therapy may be required. Administration of intravenous crystalloids is indicated if extensive vomiting and diarrhea occurred or if hemoglobinuria or hypotension is evident (49).

 CONCLUDING REMARKS

The ingestion of Allium species by various animals may lead to toxicosis; however, dogs and cats deserve special attention since they are most susceptible. Allium toxicosis is typically diagnosed through a combination of history, clinical signs, and microscopic confirmation of a Heinz body-type hemolytic anemia that if is quickly performed can allow veterinarians to give a support treatment in order to avoid animal death. It is important to carefully monitor the erythron of affected animals for several days after ingestion since it is when the anemic nadir usually occurs. Antioxidants - such as sodium ascorbate, vitamin E, and acetylcysteine - have minimal protective effects on onion powder toxicosis in cats (62). Diets with low potential oxidants are recommended; semimoist food that contains propylene glycol should be avoided, particularly for cats (63).

Additionally, it is also important to educate pet owners to not feed their animals with Allium-containg food and not to store Allium in places accessible to their pets; these measures may lead, in long term, to a better control of this particular life-threatening toxicosis.

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Wild and domestic Allium species have been used as ingredients in many dishes and with ethnomedical purposes for many years. This plant is rich in two chemical groups that are thought to provide benefits to human health: flavonoids and alk(en)yl cysteine sulfoxides. Apart from its culinary uses (fresh, cooked or dehydrated), medicinal properties have been attributed it since ancient times, prompting in recent years an accurate chemical analysis of its most characteristic active components. Compounds from onions have a range of health benefits such as anticarcinogenic, antiplatelet, antithrombotic, antiasthmatic, antidiabetic, fibrinolytic and hypocholesterolemic properties, and other various biological actions including antibiotic effects.


http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1678-91992011000100002&lng=en&nrm=iso&tlng=en

https://en.wikipedia.org/wiki/Onion#cite_note-Cope2005-34

History of onions - strong antiseptic qualities

Summary

Have people started consuming onions because of its strong anti-septic qualities?

Onion consumption started around in dry countries like Egypt. Onions prevent thirst. So, it is possible that onions were first used for their thirst quenching qualities and later for their antiseptic / antibacterial properties. These anti-septic /anti-bacterial qualities may be the cause of various therapeutic qualities of onions like cure vision problems, joint problems, induce sleep, heal mouth sores, dog bites, toothaches, dysentery, headaches, snakebites, and hair loss.

By the Middle Ages, the three main vegetables of European cuisine were beans, cabbage, and onions.

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History 

It is presumed our predecessors discovered and started eating wild onions very early – long before farming or even writing was invented. Very likely, this humble vegetable was a staple in the prehistoric diet.

Most researchers agree the onion has been cultivated for 5000 years or more.

Since onions grew wild in various regions, they were probably consumed for thousands of years and domesticated simultaneously all over the world.

Onions grew in Chinese gardens as early as 5000 years ago and they are referenced in some of the oldest Vedic writings from India. In Egypt, onions can be traced back to 3500 B.C. There is evidence that the Sumerians were growing onions as early as 2500 B.C. One Sumerian text dated to about 2500 B.C. tells of someone plowing over the city governor's onion patch.

Many archaeologists, botanists, and food historians believe onions originated in central Asia. Other research suggests onions were first grown in Iran and West Pakistan.

My note: Predominantly dry areas and also hot weather.

Qualities of onions why onion use may have started: 

Onions prevented thirst. (My note: Perhaps, this is why the use of onions picked up in dry countries like Egypt. And now, Libya where 90% of the country is desert has the highest per capita consumption of onions). 

In Egypt, onions were considered to be an object of worship.

In mummies, onions have frequently been found in the pelvic regions of the body, in the thorax, flattened against the ears, and in front of the collapsed eyes.

Egyptologists believe it was because onions were known for their strong antiseptic qualities, which construed as magical, would be handy in the afterlife.

In India as early as the sixth century B.C., the famous medical treatise Charaka – Sanhita celebrates the onion as medicine – a diuretic, good for digestion, the heart, the eyes, and the joints. 

Likewise, Dioscorides, a Greek physician in first century A.D., noted several medicinal uses of onions. The Greeks used onions to fortify athletes for the Olympic Games. Before competition, athletes would consume pounds of onions, drink onion juice, and rub onions on their bodies.

The Romans ate onions regularly and carried them on journeys to their provinces in England and Germany. Pliny the Elder, Roman's keen-eyed observer, wrote of Pompeii's onions and cabbages. Before he was overcome and killed by the volcano's heat and fumes, Pliny the Elder cataloged the Roman beliefs about the efficacy of the onion to cure vision, induce sleep, heal mouth sores, dog bites, toothaches, dysentery, and lumbago.

 The Roman gourmet Apicius, credited with writing one of the first cookbooks (which dates to the eighth and ninth centuries A.D.), included many references to onions.

By the Middle Ages, the three main vegetables of European cuisine were beans, cabbage, and onions. In addition to serving as a food for both the poor and the wealthy, onions were prescribed to alleviate headaches, snakebites, and hair loss. They were also used as rent payments and wedding gifts.

Later, the first Pilgrims brought onions with them on the Mayflower. However, they found that strains of wild onions already grew throughout North America. Native American Indians used wild onions in a variety of ways, eating them raw or cooked, as a seasoning or as a vegetable. Such onions were also used in syrups, as poultices, as an ingredient in dyes, and even as toys. According to diaries of colonists, bulb onions were planted as soon as the Pilgrim fathers could clear the land in 1648.

https://www.onions-usa.org/all-about-onions/history-of-onions

US - onion consumption has risen over 70 percent in the last two decades

U.S. Consumption Trends

Per capita onion consumption has risen over 70 percent in the last two decades, from 12.2 pounds per person in 1982 to 20 pounds per person in 2010.

My note: Is this rise in consumption of onions one of the causes of increase in diseases among Americans? Onions are fructans and part of FODMAPs, a group of carbohydrates.

FODMAPs are osmotic, which means that they pull water into the intestinal tract. That can cause abdominal pain, bloating, and diarrhea. When the carbohydrates enter the small intestine undigested, they move on to the colon, where bacteria begin to break them down. That process causes fermentation, and one product of fermentation is gas.

Not all carbohydrates are considered fodmaps, but many types of foods contain them, including foods that are high in fructose, like honey, apples, mangoes, and watermelon; dairy products, like milk and ice cream; and fructans, such as garlic and onions.

http://healthsummary.blogspot.in/search/label/FODMAPS

World Consumption Trends

World onion production is estimated at approximately 105 billion pounds each year. The average annual onion consumption calculates to approximately 13.67 pounds of onions per person across the world.

Libya has the highest consumption of onions with an astounding average per capita consumption of 66.8 pounds.

https://www.onions-usa.org/all-about-onions/consumption

As per history of onions, Egypt is another country where onions were widely used historically. Like Libya, Egypt is also a dry and hot weather country. 

https://www.onions-usa.org/all-about-onions/history-of-onions


Libya - 90% of the country is desert and has extremely hot weather 

The Libyan Desert, which covers much of Libya, is one of the most arid and sun-baked places on earth. In places, decades may pass without seeing any rainfall at all, and even in the highlands rainfall seldom happens, once every 5–10 years.

https://en.wikipedia.org/wiki/Libya

Summary

My note:

So, perhaps, onion as a food may be helpful in extremely dry and hot weather like Libya and Egypt.

Perhaps, it may not be suitable to eat onions in humid weather, cold weather, winters and at night time.

Is it possible that onions may be killing beneficial bacteria?

Onion type may help in fighting drug-resistant tuberculosis

The study led by Sanjib Bhakta of University College London (UCL) in the UK found that the antibacterial properties extracted from the Persian shallot could increase the effects of existing antibiotic treatment.

My note: Is it possible that onions may be killing beneficial bacteria?


https://www.hindustantimes.com/fitness/onion-type-may-help-in-fighting-drug-resistant-tuberculosis/story-OM1Wtt9JU4meEKiC78fnlM.html

Why No Garlic or Onions?

One of the most common questions asked to me is this: "Why don't you eat garlic and onions?"

Here's my short answer: As a devotee of Krishna and a practicing Bhakti-yogi, I don't eat garlic and onions because they cannot be offered to Krishna.

Here's my longer answer:

You may know that onions and garlic are botanical members of the alliaceous family (alliums) - along with leeks, chives and shallots.

According to Ayurveda, India's classic medical science, foods are grouped into three categories - sattvic, rajasic and tamasic - foods in the modes of goodness, passion and ignorance. Onions and garlic, and the other alliaceous plants are classified as rajasic and tamasic, which means that they increase passion and ignorance.

Those that subscribe to pure brahmana-style cooking of India, including myself, and Vaishnavas - followers of Lord Vishnu, Rama and Krishna - like to only cook with foods from the sattvic category. These foods include fresh fruits, vegetables and herbs, dairy products, grains and legumes, and so on. Specifically, Vaisnavas do not like to cook with rajasic or tamasic foods because they are unfit to offer to the Deity.

Rajasic and tamasic foods are also not used because they are detrimental to meditation and devotions. "Garlic and onions are both rajasic and tamasic, and are forbidden to yogis because they root the consciousness more firmly in the body", says well-known authority on 

Ayurveda, Dr.Robert E.Svoboda.

Some branches of western medicine say that the Alliums have specific health benefits; garlic is respected, at least in allopathic medical circles, as a natural antibiotic. In recent years, while the apparent cardiovascular implications of vegetable Alliums has been studied in some detail, the clinical implications of onion and garlic consumption from this point of view are still not well understood.

Nevertheless, there are still many adverse things to say about garlic and onions. Not so well known is the fact that garlic in the raw state can carry harmful (potentially fatal) botulism bacteria. Perhaps it is with an awareness of this that the Roman poet Horace wrote of garlic that it is “more harmful than hemlock".

It should be pointed out that Garlic and onion are avoided by spiritual adherents because they stimulate the central nervous system, and can disturb vows of celibacy. Garlic is a natural aphrodisiac. Ayurveda suggests that it is a tonic for loss of sexual power from any cause, sexual debility, impotency from over-indulgence in sex and nervous exhaustion from dissipating sexual habits. It is said to be especially useful to old men of high nervous tension and diminishing sexual power.

The Taoists realized thousands of years ago that plants of the alliaceous family were detrimental to humans in their healthy state. In his writings, one sage Tsang-Tsze described the Alliums as the "five fragrant or spicy scented vegetables" - that each have a detrimental effect on one of the following five organs - liver, spleen, lungs, kidneys, and heart. Specifically, onions are harmful to the lungs, garlic to the heart, leeks to the spleen, chives to the liver and spring onions to the kidneys.

Tsang-Tsze said that these pungent vegetables contain five different kinds of enzymes which cause "reactions of repulsive breath, extra-foul odour from perspiration and bowel movements, and lead to lewd indulgences, enhance agitations, anxieties and aggressiveness," especially when eaten raw.

Similar things are described in Ayurveda. 'As well as producing offensive breath and body odour, these (alliaceous) plants induce aggravation, agitation, anxiety and aggression. Thus they are harmful physically, emotionally, mentally nd spiritually'.

Back in the 1980's, in his research on human brain function, Dr Robert [Bob] C. Beck, DSc. found that garlic has a detrimental effect on the brain. He found that in fact garlic is toxic to humans because its sulphone hydroxyl ions penetrate the blood-brain barrier and are poisonous to brain cells.

Dr Beck explained that as far back as the 1950s it was known that garlic reduced reaction time by two to three times when consumed by pilots taking flight tests. This is because the toxic effects of garlic desynchronize brain waves. "The flight surgeon would come around every month and remind all of us: "Don't you dare touch any garlic 72 hours before you fly one of our airplanes, because it'll double or triple your reaction time. You're three times slower than you would be if you'd [not] had a few drops of garlic."

For precisely the same reason the garlic family of plants has been widely recognized as being harmful to dogs.

Even when garlic is used as food in Chinese culture it is considered harmful to the stomach, liver and eyes, and a cause of dizziness and scattered energy when consumed in immoderate amounts.

Nor is garlic always seen as having entirely beneficial properties in Western cooking and medicine. It is widely accepted among health care professionals that, as well as killing harmful bacteria, garlic also destroys beneficial bacteria, which are essential to the proper functioning of the digestive system.

Reiki practitioners explain that garlic and onions are among the first substances to be expelled from a person’s system – along with tobacco, alcohol and pharmaceutical medications. This makes it apparent that alliaceous plants have a negative effect on the human body and should be avoided for health reasons.

Homeopathic medicine comes to the same conclusion when it recognizes that red onion produces a dry cough, watery eyes, sneezing, runny nose and other familiar cold-related symptoms when consumed.

These are just some of the reasons I avoid leeks, chives, shallots, garlic and onions.

http://www.kurma.net/essays/e19.html

Sulfur rich foods - onions/garlic

Wind Surfer Florida 16 hours ago

Lots of health conscious people worry about mercury contamination from fish eating. According to recent JAMA report on fish eating, Alzheimer's and mercury, no fish eaters out of 286 deceased participants in Chicago area had mercury related dementia-Alzheimer's symptoms. Rather fish eating habit mitigated possible negative impact of brain deterioration on APOe4 gene holders( about 25% out of 286 people), most susceptible people for Alzheimer's. We are under-informed on detoxification by sulfur and selenium that attach to mercury, lead, arsenic or other toxic metals in our body for excretion. According to Dr. Russell Jaffe, a detoxification and antioxidant expert, most of us are in deficit of sulfur or selenium because we are not eating sulfur or selenium containing foods such as onion/garlic group or broccoli/cabbage group, enough on a regular basis. Fortunately most of the ocean fish contains more selenium than mercury. This is the reason why above-mentioned fish eaters didn't have mercury related brain deterioration, though they had higher mercury level but also higher selenium level at the same time.

Soucre: One of the comments in the article below:
http://well.blogs.nytimes.com/2016/10/07/why-is-fish-good-for-you-because-it-replaces-meat/?smid=fb-nytimes&smtyp=cur&_r=0