Natural Dietary Toxins

Naturally-Occurring Dietary Toxins

 
dietary toxins
 

People vary, genetics vary, immune systems vary, microbiomes vary, cultures vary, and diets vary.

Today we're going to be talking about the non-varying (common) toxins that naturally occur in diets.

Contents:

  1. Basics
  2. What Is Food?
  3. Genetics Play A Role In Dietary Toxins
  4. Environmental Contaminants
  5. Naturally Formed Substances
  6. Substances Formed From Product Abuse
  7. Substances Formed From Processing
  8. Substances Passed From Sealife To Humans
  9. Substances Passed From Animals To Humans
  10. Food-Drug Interactions

Basics

Everything is toxic, it's the dose that's the poison. R

Examples:

  • Licorice - large amounts (100g/day) can cause cardiac arrest R
  • Water - large amount (4–5 liters) is consumed in a relatively short time (2–3 hours) can kill you R
  • Vitamin A - large acute (or chronic) amounts cause liver failure and kill you R R

What Is Food?

The FDA deems what's generally regarded as safe (GRAS) - content of fats, carbohydrate, protein, potential allergens, caloric value, etc, but doesn't provide information about toxins that may be inherent in the foods or formed during processing. R

If some foods are toxic, do we still call them food? 

According to the FDA: 

The term “food” means (1) articles used for food or drink for man or other animals, (2) chewing gum, and (3) articles used for components of any such article." R

Let's break this down:

  1. includes what humans and animals will eat (eggs, meat, etc)
  2. more of a political consideration than anything else, as there was some disagreement whether chewing gum was swallowed or expectorated
  3. articles used for components of any such article - simply those substances used to make food 

Also the law prohibits the sale of food “if it consists in whole or in part of any filthy, putrid, or decomposed substance, or if it is otherwise unfit for food”

A food shall be deemed to be adulterated—(a) (1) If it bears or contains any poisonous or deleterious substance which may render it injurious to health; but in case the substance is not an added substance such food shall not be considered adulterated under this clause if the quantity of such substance in such food does not ordinarily render it injurious to health. R
Any poisonous or deleterious substance added to any food, except where such substance is required in the production thereof or cannot be avoided by good manufacturing practice shall be deemed to be unsafe for purposes of the application of clause (2) (A) of section 402(a); but when such substance is so required or cannot be so avoided, the Secretary shall promulgate regulations limiting the quantity therein or thereon to such extent as he finds necessary for the protection of public health, and any quantity exceeding the limits so fixed shall also be deemed to be unsafe for purposes of the application of clause (2) (A) of section 402(a). R

A few potential foods are banned outright by regulation such as the slaughter of companion animals (cats, dogs and horses) for food. 

Other foods which may contain toxic substances, such as prussic acid in peach leaves, β-thujone in wormwood, saxitoxin in seafood, etc also have some regulation, but not the same.

Genetics Play A Role In Dietary Toxins

Some dietary "toxins" are based on genetics.

Some people perceive cilantro as having an unpleasant soapy taste or rank smell. R

Some poeple can taste phenylthiourea, while others don't. R

Some people gentically lack specific food anosmia (lack of odor perception), which makes them enjoy foods more than others. R

Here are some more examples:

Disease/Syndrome Causative Food Cause Comment
Disaccharide intolerance Sucrose, dextrins Autosomal recessive trait characterized by the deficiency or absence of enzymes sucrase and isomaltase in the intestine. Attacks characterized by bloating and diarrhea.
Favism Broadbean (Vicia fava) X-linked recessive trait resulting in low amounts of glucose-P-dehydrogenase. Several subtypes known. Hemolytic anemia may result from consumption of offending foods.
Galactosemia Galactose and lactose (dairy products) Autosomal recessive trait with low levels of any one of three enzymes directly responsible for galactose metabolism. High levels of galactose in the blood results in hepatomegaly, cirrhosis, and renal failure. Infant mortality is ~75%.
Gluten intolerance Wheat, barley, gluten containing foods Autoimmune disease Sensitivity to storage protein (gliadin) in some grains.
Lactose intolerance Dairy products Inborn error of metabolism—low or no lactase enzyme in the intestine. Lactase is required to cleave lactose (a disaccharide of galactose and glucose). Bloating and diarrhea may develop.
Ornithine transcarbamylase deficiency Dietary nitrogen (primarily meat) X-linked recessive disorder resulting in low production of hepatic ornithine transcarbamylase interrupting the urea cycle and leading to accumulation of ammonia. Although usually first seen in neonates, there may be an adult onset.
Citrullinemia is another genetic disease affecting the urea cycle.
Phenylketonuria (PKU disease) Phenylalanine in foods Autosomal recessive trait characterized by inadequate hepatic phenylalanine hydroxylase. Leads to accumulation of phenylpyruvate which may accumulate in the brain and lead to seizures, mental retardation, etc. Products containing phenylalaine must be labeled.
Refractory sprue Wheat, barley and rye Autoimmune disorder triggered by gliadin, a gluten storage protein. Unlike common celiac sprue, adherence to a gluten-free diet may not cause symptoms to abate.
Trimethylaminuria Fish Autosomal recessive resulting in low production of flavin containing monoxygenase enzyme 3 (FMO3). Fish odor syndrome. Failure to breakdown trimethylamine, a build of which results in a fish odor.
Very long chain Acyl CoA dehydrogenase deficiency (LCAD) Very long chain fatty acids Autosomal recessive trait resulting from a mutation in the HADHA gene. Prevents mitochondrial metabolism of very long chain fatty acids.

Source - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3153292

Environmental Contaminants

Selenium

Selenium gets into our food from its ability to turn from the inorganic form to organic form in plants.R

Getting high amounts of selenium in the diet (very common in China) can cause selenosis, with symptoms such as loss of hair, deformity, loss of nails, increased blood selenium levels, diarrhea, fatigue, a garlic-like odor of the breath and bodily secretions, irritability, peripheral neuropathy, and skin lesions. R

Around 3–5 mg/day (0.05–0.08 mg/kg/day) will cause selenosis. 

The EPA recommends a RFD of 0.005 mg/kg bw/day, or 350 µg/day. R

Mercury

Inhalation of mercury is very toxic and can lead to mental deterioration and subsequently named “mad hatter syndrome”. R

We get it from our environment, especially in polluted areas, as burning coal can release mercury, or in our teeth as amalgams. R

Mercury also gets into our food from methylmercury (from bacteria usually) and elemental merucry. R

Methyl mercury exposure may cause developmental problems, neurological paresthesias, ataxia, dysarthria, hearing defects and death. R

The most common source for methylmercury is via fish (biggest problem is from bonito, halibut, mackerel, marlin, shark, swordfish, and bluefin tuna). R

Naturally Formed Substances

β-Thujone

Thujone (monoterpene ketone) comes from essential oils, such as sage, clary, tansy, wormwood, and cedar. R

The alpha- or beta- forms of thujone in food and beverages are regulated by law in several countries as they can be toxic. 

Although, oils from these plants are still used in flavorings, such as Absinthe (made from wormwood), or vodka in Sweden (using wormwood and vermouth, chartreuse, and Benedictine as thujone-based flavorings). R

Sage oil (containing 20-30% alpha/beta thujone) can be found in flavorings for sausages, meats, condiments and sauces. R R

Both alpha- and beta-thujone act as noncompetitive blockers of the gamma-aminobutyric acid (GABA)-gated chloride channel. R

Sage, as well as others such as hyssop and cedar all have thujone which has shown to directly act on the central nerouvs system (CNS), causing rebound seizures. R

Thujone is also believed to be the main toxin in absinthe - causing addiction, hyperexcitability and hallucinations. R

Injestion of 10 mL of essential oil of wormwood has shown to cause renal failure. R

Prussic Acid

 
prussic acid cyanide
 

Prussic acid (also known as hydrocyanic acid, hydrogen cyanide, or cyanide) is commonly found in cherry, apple and peach pits that are damaged.  R R

When cyanogenic glycosides in these plants are damaged and come into contact with beta-glycosidase or emulsion enzymes, these enzymes then release cyanide from the glycoside. R R

Cyanide prevents the body’s cells from utilizing oxygen, resulting in cellular necrosis and tissue damage. R R

Prussic acid poinoning can cause rapid breathing, trembling, incoordination and in extreme cases, respiratory and/or cardiac arrest. R R

Most fruits are safe but an outlier is cassava, which needs to be properly handeled or chronic intake of cassava ma cause “tropical ataxic neuropathy”, the result of demyelinization of the optic, auditory, and peripheral nerve tracts. R R

Per FDA, cherries must have less than 25ppm in cherry pits, cherry leaves, cherry laurel leaves, eldertree leaves, and peach leaves, whereas the FDA has no regulaitons on presence of prussic acid in apple seed. R

Hypericin

Hypericin is commonly found in St. John’s wort (Hypericum perforatum).

Hyperforin and hypericin are used to alleviate symptoms of depression by their mechanism of inhibition of serotonin (5-HT) reuptake. R R

These taken with SSRI's can cause serotonin syndrome. R

em. Hyperforin is also known to induce cytochrome P450 enzymes CYP3A4 and CYP2C9, which can lead to increased metabolism of certain drugs and decreased clinical response. R

In large doses, St. John’s wort is poisonous to grazing animals - giving them general restlessness and skin irritation, hindlimb weakness, panting, confusion, depression and in some instances, mania and hyperactivity resulting in the animal running in circles until exhausted. R

In humans, St. John’s wort may result in photosensitivity and liver damage (at high/continuous doses). R

Goitrogens

Goitrogens (glucosinolates) is able to suppress the function of the thyroid gland by interfering with the uptake of iodine. 

Iodine is an essential nutrient in growth, cognitive function, and hormonal balance, where low levels of developmental iodine can cause cognitive deficiencies. 

The decrease in iodine uptake causes the thyroid gland to enlarge, forming a goiter.

Goitrogenic foods include: R

  • broccoli
  • brussels sprouts
  • cabbagr
  • canola
  • cassava
  • cauliflower
  • mustard greens
  • pears
  • peaches
  • peanuts
  • radishes
  • rapeseed
  • spinach
  • soybeans
  • strawberries
  • sweet potatoes

Goiter has also been attributed to the consumption of large quantities of uncooked kale or cabbage. R

Cooking in high heat inactivates the goitrogenic substances. R

Cassava must be properly processed-dried, soaked in water or baked to effectively reduce the linamarin content. R

Erucic Acid

Rapeseed oil had been used for hundreds of years as oil for lamps and more recently as machine oil lubricant.

In food, rapeseed oil is used as a food ingredient and cooking oil. R

Erucic acid is the major toxic substance in rapeseed oil.

It is a long-chain fatty acid with one unsaturated carbon-carbon bond (C22:1).

High levels of erucic acid have been liked to fatty deposit formation in heart muscle in animals. R 

Erucic acid is poorly oxidized by the mitochondrial β-oxidation system, especially in the heart, which results in an accumulation of erucic acid, producing fat generation of the heart. R

For example, feeding high levels of rapeseed oil to rats can significantly increase cholesterol levels in the adrenal glands and lipidosis in the heart. R R

In chickens, ducks, and turkeys, feeding of high levels of rapeseed resulting in growth retardation, mortality, and a thickening of the epicardium and increased fibrous tissue in different areas of the myocardium. R

These effects have yet to be fully confirmed in humans, but the FDA limits the amount of erucic acid in Canola oil to no more than 2% of the component fatty acids (21 CFR 184.1555). R R

Furocoumarins

Furocoumarins act as natural pesticides and are produced in response to stress, to aid plants in defense against viruses, bacteria, fungi, insects and animals. R

They are found in Rutaceae (such as citrus fruits) and Umbelliferae (such as parsnip, parsley, celery, carrots). R

The three most active furocoumarins from UV-induced stress (320–380 nm) are: R

  1. psoralen
  2. 5-methoxypsoralen (5-MOP, bergapten)
  3. 8-methoxypsoralen (8-MOP, xanthotoxin or methoxsalen)

5-MOP and 8-MOP can produce skin tumors in experimental animals and chornic doses glandular and kidney cancers. R

Citrus fruit juice is produced utilizing the whole fruit, including the peel.

bergamottin (also known as bergamot), is a furanocoumarin naturally found in the peel of fruit that can inhibit cytochrome P450 enzyme (CYP) 3A4. R 

This can lead to a elevated concentrations of a drug (depending on which drug) in the bloodstream. R

Bergamot and other chemicals in citrus (e.g., lime, grapefruit, orange, lemon) oils are also phototoxic, causing significant toxicity to the skin when exposed to sunlight. R

Celery reportedly contains 100 ppb psoralens and parsnips as much as 40 ppm. R

There are no FDA regulations or guidelines specific to the presence of furocoumarins in food. R

Amylase Inhibitors

Wheat, rye and kidney beans all contain  α-amylase inhibitors. R

α-Amylase inhibitors are not well understood, but may protect plants against insect infestation. R

In mammals, some amylase inhibitors have been shown to attenuate the normal increase in blood glucose that occurs after ingestion of starch (by inactivation of gastric acid, pepsin or pancreatic proteinases), but are not entierly effectively to block starch and be used  as a weight loss tool, R

α-Amylase inhibitor protein is a major allergen that has been implicated in the development of occupational toxicity known as “baker’s asthma disease”. R

α-Amylase inhibitor protein can be potentially found in baked products that are derived from sources other than wheat (or bread) and symptoms of allergy include sneezing, rhinorrhea, oropharyngeal itching, hoarseness, cough and dyspnea. R

α-Amylase has been shown to retain some allergenic activity when heated to 200 °C. R

Lectins

 
lectins toxin
 

Lectins are found in all plants and animals, but the problematic ones are found in certain types of plants.

They can act as immunostimulants, which may be problematic for those with autoimmune conditions, and they're mostly found in many seed-like plants (zucchini, fruits, legumes, grains, soy, etc). R

They are proteins that bind to carbohydrates without altering their structure and can bind to/agglutinate red blood cells. R

In the intestine, they act as phytonutrients, block absorption of nutrients through the gut lining, and may alter the gut microbiome towards dysbiosis. R

Lectins can cause:

  • Growth retardation (black bean and soybean)
  • Death (castor bean lectin ricin)
  • Malabsorption of sodium, nitrogen, chloride, B12 in cells/mitochondria (Phytohaemagglutinin aka PHA - red or white kidney beans, green beans and fava beans) R
  • Nausea, vomiting, or diarrhea (PHA) R

Pressure cooking (steaming/boiling) destroys some lectins but not all of them 100%. R

I will write a whole post on lectins soon about how it works on the immune system. 

Anti-Thiamine Compounds 

Some substances act like antivitamins by destroying or decreasing the effects of a vitamin or changing its molecular composition. 

Thiaminase cleaves thiamine (vitamin V1) and is Found in foods such as fish, crab, clams, blueberries, black currants, red beets, Brussels, sprouts. 

Thiamine deficiencies can cause impaired pyruvate utilization, resulting in less ATP.  R

Cooking destroys Thiaminase. 

Pyrrolizidine Alkaloids (PAs) 

Pyrrolizidine alkaloids (PAs) are found in some plants,  seeds, herbs, dairy, honey, and veggies. R

PAs can be toxic to the liver, dna, and may be carcinogenic. R

For example, comfrey (which contain PAs) products for internal use are banned in the US and Canada, although comfrey tea is still available. R

Oxalic Acid/Oxalates

Oxalic acid (also known as oxalates) are commonly found in rhubarb, tea, spinach, parsley, purslane, asparagus, broccoli, Brussels sprouts, collards, lettuce, celery, cabbage, cauliflower, turnips, beets, peas, coffee, cocoa, beans, potatoes, berries, and carrots, as well as some food dyes. R

Oxalates bind to calcium and other minerals making them less bioavailable. 

Consuming a lot of oxalates can cause problems such as:

  • Decreased bone growth
  • Kidney stones (~65% of kidney stones consist of calcium oxalate) R
  • Renal toxicity 
  • Vomiting 
  • Diarrhea 
  • Convulsions 
  • Coma 
  • Impaired blood clotting 

Consuming more than 22g/day of oxalates may be lethal to humans. R

Cucurbitacins

Cucurbitacins are the bitter components found in the squash family (ie zucchini, cucumber, pumpkin, squash, melons, gourds). 

They act as feeding stimulants and are added to insecticides to kill bugs faster. R R

When exposed to a lot of stress, the plants produce more cucurbitacins, causing them to be more bitter can can contribute to food poisoning symptoms (stomach cramps, diarrhea, etc). 

Coumarins 

Coumarins are found in Tonka beans, melilot, woodruff, bergamot, and cassia (sold as cinnamon). R

Molds can also metabolize Coumarins into dicoumarol, which is a similar structure to vitamin K. R

Vitamin k activate prothrombin, which is converted in thromboxane and helps form blood clotting. 

By inhibiting vitamin K, dicoumarol can promote bleeding and have shown to cause death in animals (greater than 10ppm). R

Coumarins are banned from being added to foods in the US as they can cause liver toxicity and tumors in animals, although not significant in humans. R

Phytates/Phytic Acid

The sugar phytatic acid (aka phytates) is a dietary source of phosphorus and an effective chelator of zinc, copper, iron, magnesium and calcium cations. R

It's insoluble in the GI tract, can reduce mineral bioavailablilty, and can reduce digestion of food by inhibiting digestive enzymes such as trypsin, pepsin, α-amylase and ß-glucosidase. R

Phytates are found largely in bran and germ of many plant seeds and in grains, legumes and nuts, and are very high in tofu and bean curd, so may be a factor for vegans/vegetarians becoming deficient in nutrients. R

Since phytate changes the rate of food being broken down, it may be beneficial for diabetes. R

It also has antioxidant properties. R

Soaking and fermeting foods helps remove most phytic acid. R

Hypoglycin

The hypoglycin toxin (L-methylenecyclopropylalanine) inactivates several flavoprotein acyl-CoA dehydrogenases, causing disturbances of the oxidation of fatty acids and amino acids. R

Because of this hypoglycin A (HGA) can cause extreme drops in blood pressure, causing death. R R

Other symptoms (6 to 48 hours of ingestion) HGA can produce include drowsiness, repeated vomiting, thirst, delirium, fever, loose bowels, exhaustion of the muscular and nervous systems, collapse, and coma. R R

It is commonly found in Ackee, the national fruit of Jamaica and is also found in other Caribbean nations, Central America, South American and southern Florida. R

The FDA has regulations on how much HGA can be in canned foods. R

Safrole

Safrole (1-allyl-3,4-methylenedioxybenzene) is found in aromatic oils of nutmeg (Myristica fragrans), cinnamon (Cinnamomum verum) and camphor (Cinnamomum camphora) and is a major constituent of oil of sassafras (Sassafras albidum). R

It is banned by the FDA to be used as a food additive. R

In animal modles, safrole can cause weight loss, testicular atrophy, bone marrow depletion and malignant liver tumors. R

In humans its believed to be carcinogenic as it works on CYP450 enzymes and its metabolites bind to DNA. R

Sassafras is still popular in teas and herbal preparations, despite the FDA ban. R

Myristicin

Myristicin is a natural pesticide/insectisde found in nutmeg, mace, black pepper, carrot, celery parsley and dill. R

Myristicin is a weak MAOI (structurally related to mescaline) and can cause psychotropic effects:

  • Anxiety
  • Euphoria
  • Fear
  • Feeling of irresponsibility
  • Freedom
  • Increased alertness,
  • Nausea
  • Tachycardia
  • Tremor

Ingestion of greater than 5 grams of nutmeg produce symptoms that are similar to alcohol intoxication. R

It is not carcinogenic. R

Tomatine

Tomatine (α-tomatine) is found in tomatoes, especially in the unripe fruit. R

Tomatine is a natural fungicide. R

Tomatine should produce no negative effects in humans if the tomatoes are ripe, as when they ripen, the amount of tomatine significantly reduces, although microwaving has no effects on lowering tomatine levels. R

Tomatine has shown to reduce LDL cholesterol levels in animal models. R

Neurotoxins In Star Anise

Chinese star anise (Illicium verum) is a common source of anethole and the neurotoxin veranisatin. R

Japanese star anise contains the potent neurotoxins anisatin and neoanisatin and are highly poisonous to humans. R

The FDA recommends not drinking any teas with Star Anise products, although chinese and japanese star anises are different. R

Substances Formed From Product Abuse

Glycoalkaloids

 
glycoalkaloids potatoes
 

Glycoalkaloids (solanine and chaconine) are natural pesticides that are produced in potatoes, and compared to chaconine, solanine is mostly only found in eggplant, apples, bell peppers, cherries, sugar beets and tomatoes. R R

α-solanine and α-chaconine are strong acetylcholinesterase inhibitors and can disrupt cell membranes. R

Doses of 1 to 5 mg/kg have been shown to be acutely toxic to humans, and doses of 3 to 6 mg/kg have resulted in death. R

Solanine and chaconine have teratogenic effects (birth defects), causing central nervous system abnormalities in animals, although only very rare cases have been reported in humans. R

Under current FDA regulations, 20 milligrams of solanine per 100 grams (a small potato) can render it unfit to eat. R

Glycoalkaloids increase significantly when tubers are exposed to light, mechanical injury, aging and potato beetle infestation. R

Furocoumarin

Furocoumarin (angelicin, isopimpinellin, 5-MOP, 8-MOP and psoralen) comes from spoiled or diseased parsnips (2500% higher than fresh parsnips). R

It can also be found in infections and fungal diseases of celery, such as "pink rot". R

In celery it can cause dermatitis. R

Fungal infections of carrots can increase furocoumarins (155-fold increase). R

Storing of parsnips, celery, and carrots properlly should prevent high furocoumarin levels. R

Substances Formed From Processing

Heterocyclic Aromatic Amines

Heterocyclic aromatic amines (HAAs) are carcinogenic compounds (tumorous forming when ingested chronically). R

HAAs are formed from cooking proteins in high temperatures. R

The amount of HAAs found in food are dependent on cooking temperature and time (concentrations increase with higher temperatures and longer cooking times), cooking technique and equipment (concentrations of HAAs in meat are generally higher after grilling and panfrying than broiling or roasting), and the ability of HAA precursors to migrate to the surface. R

Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are also carcinogenic. R

They are formed from combustion (such as wood, coal and oil) and can easily get into food. R

PAHs are commonly found in cooked or smoked meat or fish, smoked or cured cheese, tea and roasted coffee. R

Grilling, boiling, smoking, roasting and steaming, in that order have the highest amounts of PAHs. R

Acrylamide

Acrylamide is carcinogenic, neurotoxic, toxic to reproductive organs, and genotoxic. R R

Acrylamide is produces from starch-based foods when cooked at high temperatures - fried or baked at temperatures greater than 120 °C (248 °F), including bread, bakery products, breakfast cereal, and potato products (e.g., chips, french fries).  R

Avoiding high-temperature frying and soaking grains before cooking may help reduce acrylamide levels. R

Chloropropanols

Chloropropanols are common byproducts of edible oil extraction, when they are hydrolyzed with hydrochloric acid and other chlorines (such as soybean meal, rapeseed meal and maize gluten). R

3-MCPD and 1,3-DCP are the two most commonly studied chloropropanols. 

3-MCPD can damage kidneys and cause DNA damage in animal models. R

1,3-DCP hepatotoxic, genotoxic, and carcinogenic in animal models. R

3-MCPD is commonly found in: R R

  • soy sauce
  • oyster sauce
  • cereal
  • toasted bread
  • coffee
  • cheese
  • licorice
  • baked goods
  • processed garlic
  • liquid smokes
  • malts
  • cured or smoked meat or fish
  • foods containing acid-HVP as a savory ingredient (soups, prepared meals, savory snacks, gravy mixes and stick cubes)

Furan

Furan is a byproduct of adding high amounts of energy to a carbohydrate, such as heat processed in cans and jars (such as soups, pastas, sauces, gravy and baby food) and brewed coffee, typically contain the highest concentrations. R

It can also be synthesized from vitamin C, amino acids, reducing sugars, organic acids, carotenes and polyunsaturated fatty acids in the presence of heat. R

Furan is genotoxic, mutagenic and clastogenic in animal models, and possibly carcinogenic in humans. R R R R

Currently, there are no FDA regulations specific to the level of furan in food.

Trans Fat

Trans fatty acids (also known as trans fat) in the diet originate from two sources:

  1. Bacterial hydrogenation - which produces trans fatty acids that are found in beef and mutton fat, milk and butter
  2. Hydrogenation of liquid oils - which produces solid fats and partially hydrogenated oils such as margarines, spreads, shortenings and frying oil, which are more stable than liquid oils

There is an increased correlation of trans fats to increased LDL cholesterol levels and increased risk of coronary heart disease (CHD) independent of other risk factors in large epidemiological studies. R

Nitrosamines

 
nitrosamines
 

Nitrosamines are formed from nitrites or other nitrosating agents with amines in food (or in the body), under acidic conditions. 

They are commonly added to foods or formed naturally from bacteria acting on nitrate. R

They are commonly found in cheese, soybean oil, canned fruit, meat products, cured or smoked meats, fish and fish products, spices used for meat curing, and beer and other alcoholic beverages. R

Drying, kilning, salting, smoking or curing promotes formation of nitrosamines.

Nitrosamines are reported to be carciongenic in animals and probably in humans as well. R R

The USDA monitors finished meat products do not have nitrite is not present in amounts exceeding 200 ppm. R

Biogenic Amines

Biogenic amines are normally found in the body and can be formed by microbial decarboxylation of amino acids. 

Biogenic amines are naturally found in fermented meat, beverages (red wine) and dairy products, sauerkraut, and spoiled fish (esp tuna, mackerel, saury, and bonito). R

The main biogenic amines in food are histamine, tyramine cadaverine, putrescine, spermidine and spermine, with histamine and tyramine being the most problematic (see histamine intolerance).

Histamine from spoiled fish is a common reason for food poisoning and non-IgE fish-related allergies.

Monoamine oxidase inhibitor (MAOI) drugs inhibit metabolism of amines and can make problems with biogenic amines worse. R

Substances Passed From Sealife To Humans

Saxiotoxin

 
saxiotoxin mollusks
 

Paralytic shellfish poisoning (PSP) is caused from saxitoxins, found in mollusks. 

Saxitoxin binds to voltage-dependent sodium channels, which blocks neuronal activity. R

This can lead to numbness of extremities, loss of motor control, drowsiness, incoherence, and death (1–4 mg of ingestion) from loss of respiratory function. R

Cooking does not get rid of saxitoxin. R

Brevitoxins

Some flagella (like K. brevis) can produce brevitoxins that are toxic to fish, but not mollusks, and thus can accumulate in them, even healthy looking mollusks. 

Brevitoxins can cause neurotoxic shellfish poisoning (NSP) in humans, which acts on sodium transports in the autonomic nervous system and causes inhibition of neuromuscular transmission in skeletal muscle. R R

K. brevis is usually responsible for red tides, as seen in Gulf of Mexico and along the southern Atlantic coast of North America.

The FDA has established an action level of 0.8 ppm of brevetoxins. R

Domoic Acid

Domoic acid is produced from diatoms and can cause amnesic shellfish poisoning (ASP). R

Diatoms are regularly consumed by mussels, scallops, clams and crabs and when eaten domoic acid can act similarly to glutamate in the brain (strong agonist of glutamate receptors). R

If persistent in the body, domoic acid can persistently activate kainite glutamate receptors, thus leading to increased calcium levels in cells, leading to neuronal death and lesions of the brain. R 

ASP can cause gastroenteritis, dizziness, disorientation, lethargy, seizures, loss of short term memory, respiratory difficulty, coma and possibly death. R R

Human reports of death from domoic acid have been seen from consumption of contaminated mussels, sardines and anchovies. R

The FDA has established an action level of 20 ppm for domoic acid, except in the viscera of Dungeness crab, where 30 ppm is permitted. R

Okadaic Acid

Okadaic acid and dinophysistoxins produced from dinoflagellates can cause diarrhetic shellfish poisoning (DSP) as mollusks consume and accumulate them. R

Okadaic acid and dinophysistoxins are inhibitors of serine/threonine phosphatases, causing dysregulation of metabolism, ion balance, neurotransmission and cell cycle regulation. R

Ciguatoxin

Ciguatoxin comes from the flagella Gambierdiscus toxicus which grows near coral reefs. R

Ciguatoxin can be found in high levels in barracuda, snapper, grouper and jacks. R

Ciguatoxin has shown to cause ciguatera fish poisoning (CFP). R

Ciguatoxin is stronger than brevitoxin (as discussed above) at binding to voltage-dependent sodium channels and causing neurotoxicity and rarely death. R

Gempylotoxin

Some fishes (like Escolar, Oilfish, Cocco, Butterfish) have wax esters in their oils that can cause diarrhea. R R

Tetramine

Tetramine is a neurotoxin that is commonly found in whelks and sea snails. 

It can cause eyeball pain, headache, dizziness, abdominal pain, ataxia, tingling in the fingers, nausea and diarrhea. R R

Removing the salivary glands of the whelks and sea snails can prevent tetramine poisoning. R

Trimethylamine Oxide

Trimethylamine oxide (TMAO) breaks down to trimethylamine in the gut, probably by enteric bacteria, and can act as a neurotoxin to humans. R

TMAO found in fish (such as shark) can be lowered by boiling it or by repeatedly freezing/thawing it. R R

Substances Passed From Animals To Humans

Grayanotoxins

 
grayanotoxins honey
 

Grayanotoxins are found in honey (made from the nectar of the flowers), milk from a cow having eaten the foliage and meat (such as hot dogs) roasted on oleander sticks. R

Grayanotoxins consists of a series of cardiac glycosides: thevetin, convallarin, steroidal, helleborein, ouabain, and digitoxin. R

Grayanotoxins bind to sodium channels in muscles and the heart. R

Tremetol

Tremetol (or tremetone) is found in milk from cows that have eaten rayless goldenrod or white snakeroot. R R 

It can cause “milk sickness” also known as “puking fever”, “sick stomach”, “the slows” and “the trembles.  R R 

Tremetol is not regulated by the FDA.

Food-Drug Interactions

Enzyme or Transporter Food Drug
CYP1A2 Caffeine, theophylline, grapefruit juice (naringen and furanocourmarins bergmottin and dihydroxybergamotin), grape juice, cruciferous vegetables, apiaceous vegetables, cooked meat Clozapine, fluvoxamine, imipramine
CYP2E1 Watercress and possibly other isothiocyanate-containing cruciferous vegetables; polyunsaturated fatty acids (corn oil, menhaden oil) Ethanol, halothane, enflurane
CYP3A4 Grapefruit, orange juice, red wine, possibly other polyphenol-containing substances, St. Johns wort, garlic Ketoconazole, cyclosporine, erythromycin, protease inhibitors, HMG-CoA reductase inhibitors
UGT and GST Brussels sprouts, cabbage, watercress, broccoli Acetaminophen, oxazepam, morphine, ibuprofen
P-glycopeptide and OATP Vegetables, fruit juice, St. Johns wort Digoxin, cyclosporine, parvastatin

Source - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3153292