Toxicants in foods and their effects on nutrition

Potential sources of toxicants in food include nutrients, natural food toxicants, contaminants, and chemicals or substances intentionally added to food (food additives). One usually does not relate the ingestion of a specific nutrient with concerns about the toxicity of that nutrient. However, intakes of essential dietary chemicals from zero to excessive produce responses, from lethal because of nutrient deficiency to an optimal health response and back to lethal because of intolerably high...

Epidemiology in Food and Nutritional Toxicology

Extrapolation of data from animals to humans can be problematic because of differences between species. Human studies can be conducted by performing epide-miological studies. Epidemiology is the examination of the distribution and determinants of diseases or health-related circumstances, good or bad, in identified populations. Epidemiology's intent is to apply what is learned from such examination to the control of health-related problems. Epidemiological studies uncover relationships between...

Defining the terms and scope of food and nutritional toxicology

In essence, toxicology is the science of poisons, toxicants, or toxins. A poison, toxicant, or toxin is a substance capable of causing harm when administered to an organism. Harm can be defined as seriously injuring or, ultimately, causing the death of an organism. This is a rather simplistic definition, because virtually every known chemical or substance has the potential for causing harm. The term toxicant can be a synonym for poison, or the term poison might be more appropriate for the most...

Dioxins

FIGURE 16.9 Tetrachlorodibenzo-p-dioxin (TCDD). Liver lesions, adrenal atrophy, chloracne, and kidney abnormalities have been reported. Both skin and kidney effects appear in many species, which are likely targets for TCDD toxicity. In addition, TCDD is a promoter of carcinogenesis and is a carcinogen. Liver tumors and tumors of the mouth, nose, and lung have been found. TCDD may be three times more potent a carcinogen than is aflatoxin Bj. In addition, TCDD is a potent teratogen in mice and...

Aflatoxin

Initially, the terms mycotoxin and aflatoxin were used interchangeably, because aflatoxin is probably the most important mycotoxin in food however, mycotoxin has now become a generic term and is defined as any toxin of fungal origin. Aflatoxin refers to toxins produced by Asperigillus flavus. The mold is prevalent in nuts, cottonseeds, corn, and figs. Most animals, including humans, and poultry are particularly susceptible to aflatoxicosis. Interestingly, the mouse is totally resistant to...

Arsenic

Populations have always been exposed to high arsenic levels in food, drinking water, wine, and other sources. Arsenic is found as inorganic and organic compounds. It is found naturally in rocks and soil worldwide, and industrial effluents contribute significant amounts. Arsenic is used in large quantities in the manufacture of glass to eliminate a green color caused by impurities of iron compounds. Arsenic is sometimes added to lead to harden it and is also used in the manufacture of such...

Animal Care

The humane treatment of animals is not covered explicitly in the GLP requirements. However, the USDA has specific requirements for the humane treatment of animals. The Institutional Animal Care and Use Committee (IACUC) reviews and approves study protocols, and any changes to a protocol must be submitted to the IACUC coordinator for consideration. The main purpose of the IACUC is to ensure the humane treatment of animals in GLP studies. In addition, nonclinical labs should strictly enforce...

Red No

In 1990, FDA outlawed several uses of the strawberry-toned FD& C Red No. 3, invoking the Delaney Clause. The banned uses include cosmetics and externally applied drugs, as well as uses of the color's non-water-soluble form. FDA previously had allowed these provisional uses while studies were in progress to evaluate the color's safety. Research later showed large amounts of the color cause thyroid tumors in male rats. Though FDA viewed the cancer risk by Red No. 3 as low, ca. 1 in 100,000...

Water Soluble Vitamins

As a group, these vitamins tend to have fewer toxic effects compared with fat-soluble vitamins, mainly because water-soluble vitamins are not retained in the body to the same extent as fat-soluble vitamins. When these vitamins reach urinary threshold levels, the excess is eliminated rapidly in the urine. Thus, discernible harm to the individual can be avoided because of these elimination factors preventing accidental or deliberate ingestion of water-soluble vitamins. Nevertheless, adverse...

Food Additives Colors and Flavors

For some consumers, processed food conjures up images of a food dead of nutrients and stripped of vitamins and fiber, and replaced with chemicals and worthless filler, or technology toying with nature in the name of profit. From the beginning of time, humans have invented ways to preserve food after harvest and slaughter to make it last longer, be more palatable, and, in recent times, be more readily available for use. Fire and root cellars were among the first forms of food processing humans...

Ergot alkaloids and ergotism

Mycotoxicoses have been known for a long time. Ergotism occurred in the Middle Ages, around the 14th century in Europe. Ergot is a fungus, Claviceps purpurea, that grows on rye, and the consumption leads to intoxications and episodes of hallucinations, delirium, and convulsion and causes arteriolar spasms and gangrene. The gangrenous effects are associated with alkaloids that are partial a-adrenergic agonists and promote vasoconstriction, and the hallucinogenic effects are because the ergot...

Foodborne Viruses and Human Diseases

Virus Human Disease (Common Source) Hepatitis A Hepatitis A (shellfish, vegetables, milk) Hepatitis E Hepatitis E (clinically indistinguishable from hepatitis A disease, water-borne, person to person) Norwalk-like Gastroenteritis (salads, raw oysters, clams) Rotavirus Gastroenteritis (transmitted by the fecal-oral route, person-to-person spread through Caliciviruses Acute nonbacterial infectious gastroenteritis and viral gastroenteritis (fecal-oral routes via person-to-person contact or...

Oral ingestion studies

Under normal situations, the oral route is usually the means by which toxicants from food enter organisms. Through industrial exposures or other rare situations, toxicants from foods may enter organisms by inhalation as a dust or vapor suspension in the air or percutaneous (dermal) penetration, respectively. The toxicologist selects the experimental route to test the bioactivity of a chemical based on the common route of exposure for the substance. Selection of the route of exposure is...

Food Irradiation

For many consumers, the phrase food irradiation conjures up images of devastation, debilitation, or concerns regarding danger to both life and the environment. Much of the unfounded fear is created by equating irradiation with its root word radiation. Food irradiation is a food preservation process or method that can protect food from microorganisms, insects, and other pests that can make our food supply unsafe or undesirable. Compared with other food preservation processes, food irradiation...

Cadmium

Extensive industrial use has contributed to cadmium being widely distributed in the environment. Because organic cadmium compounds are unstable, most of the cadmium in foods is as inorganic cadmium salts. Cadmium may be electrolytically deposited as a coating on metals, chiefly iron or steel, on which it forms a chemically resistant coating. Alloys of cadmium with lead and zinc are used as a solder for iron. Cadmium salts are used in photography and to manufacture fireworks, rubber, fluorescent...

Byproducts of irradiation

Previously, approximately 65 products were identified as unique compounds formed during food irradiation. Since then, all but six have been accounted for as naturally occurring or found in other food-processing situations. Free radical compounds are generated, but are not unique to food irradiation. One compound was traced to be a contaminant of a chemical used to sterilize the hooks from which carcasses were hung in slaughterhouses. After several decades of research, including more than 1300...

Antibiotic resistance

Pathogenic bacteria that have become resistant to antibiotic therapy are an increasing public health problem. For example, tuberculosis, gonorrhea, malaria, and ear infections in children are just a few of the diseases that have become hard to treat with antibiotic drugs. Part of the problem is that microorganisms that cause infections are extremely hardy and can develop ways to endure drugs meant to kill or weaken them. This antibiotic resistance (antimicrobial resistance or drug resistance),...

Gender and age

Toxicity can depend on sex, circadian rhythms, and age. Such dependence is well documented in both laboratory animals and humans. Diurnal variation is mostly related to eating and sleeping habits. Nocturnal animals usually have more food in their stomach in the morning than in the late afternoon. Agents that affect activity and are ingested by animals that normally eat at night exhibit a different effect compared with agents ingested by animals that sleep throughout the night. The classical...

Storage Sites Plasma Proteins

Substances found in blood or the vascular compartment bind reversibly with plasma proteins such as albumin, globulins, glycoproteins, lipoproteins, and more specifically transferrin and ceruloplasmin. Figure 8.9 shows a typical electrophoretic pattern of plasma proteins and depicts where various substances are likely to bind. Albumin can bind many substances and has a propensity for acidic compounds. More alkaline compounds are likely to bind with lipoproteins and glycoproteins. The binding is...

Insecticides

Naturally occurring or synthetic pesticides are a diverse group of chemical agents used to control undesirable pests. The introduction of synthetic pesticides had an enormous impact on agriculture and human health. Dramatic increases in agricultural production, the so-called green revolution, in the U.S. in the past decades were achieved by the use of synthetic pesticides, herbicides, and fungicides. Insecticides and fungicides have been used and are being used to reduce postharvest losses of...

Protozoa

Protozoa (protozoon, singular) are one-cell animals. With respect to food or water sources, three types are important Entamoeba histolytica, an ameba Giardia lam-blia, a flagellate and Toxoplasma gondii, a coccidian. Each has at least one active feeding form, usually termed as trophozoite, and can reproduce by simple division, and a quiescent form in which it retains infectivity during periods outside the host. Transmission is by fecal to an oral route. The major source of infection is usually...

Diet and biotransformation

The biotransformation of a toxic compound usually, but not always, results in detoxification. It can, however, lead to the metabolic activation of foreign compounds. The effect of dietary constituents on the metabolism of foreign compounds has been the subject of intensive study for many years. More than two decades ago, the term toxicodietetics was coined for the study of dietary factors in the alterations of toxicity a term that was perhaps ahead of its time. There are a multitude of dietary...

Animal Toxins and Plant Toxicants

Toxicants are produced by a variety of animals and plants and are widely distributed throughout each kingdom, from the unicellular to the multicellular. There is striking diversity of chemical structures for toxic compounds found in nature, making classification based on structure difficult. The presence of toxicants in food may have come about because animals or plants evolved means of producing chemicals to protect themselves from predators, or insects, nematodes, microorganisms, or even...

Classes of Carbohydrates

Monosaccharides Simple sugars (galactose, fructose, glucose) Disaccharides Sucrose, lactose, maltose Polysaccharides Digestible starch, dextrins, indigestible starch If healthy population groups around the world are studied, there are relatively few illustrations of toxic effects associated with carbohydrate intakes. If sufficient food is available, population groups whose diets consist mostly of carbohydrates do not suffer adverse effects. Some short-term effects such as intestinal problems...

Human Health Risks Allergenicity

Many children in the U.S. and Europe have developed life-threatening allergies to peanuts and other foods. There is a possibility that introducing a gene into a plant may create a new allergen or cause an allergic reaction in susceptible individuals. A proposal to incorporate a gene from Brazil nuts into soybeans was abandoned because of the fear of causing unexpected allergic reactions. Testing of GM foods may be required to avoid the possibility of harm to consumers with food allergies.

Principles of toxicokinetics

The study of the kinetics of chemicals in the whole organism was originally developed for drugs, and termed pharmacokinetics, which was derived from the Greek words pharmako (medicine, drug, or poison) and kinetikos (motion or movement). Thus, by definition, pharmacokinetics (PK) can apply to any foreign compound and not just drugs. However, those concerned about the use of semantically correct terms have referred to the study as chemobiokinetics or toxicokinetics (TK). TK, like PK, can be...

KXH kXH HCHO

Alcohol dehydrogenase catalyzes the conversion of alcohols to aldehydes or ketones The aldehydes require a further metabolism to acids because such compounds are usually toxic and because of their high lipid solubility are not easily excreted. Metabolism is faster with primary alcohols than with secondary alcohols, followed by tertiary alcohols (which are not readily oxidized). Other dehydrogenases play important roles in steroid, lipid, and carbohydrate metabolism, but their substrate...

TABLE 123 Phenolic Substances

Flavanone, flavone, anthocyanidin, isoflavanone, chalcone, aurone Hydrolyzable and condensed Coumarin, safrole, myristicin thiosulfate plays a key role in detoxification of cyanide. Thiosulfate originates from sulfate metabolism. More than 800 phenolic substances are known in plants. Such compounds contribute to the bitter taste, flavor, and color of foods. Table 12.3 lists some classes of phenolic substances. Most of the phenolic substances are devoid of acute toxicity. Methods are available...

Bacterial Toxins

Of the many different causes of foodborne diseases, bacteria are by far the most common. About half of all cases of diarrhea in the U.S. are of foodborne origin, and, according to the CDC, microbial diseases are on the rise. The reasons for the increase in foodborne illnesses are as follows. (1) There are better epidemiological capacities and better means to report cases, as well as better means to detect and identify foodborne illnesses. (2) Over the last few decades, people have made...

Study questions and exercises

Distinguish between intentional and incidental food additives. Provide a few examples of each and describe how incidental additives get into foods and why intentional additives (function of additives) are added to foods. 2. Discuss how the Delaney Clause has impacted on the use of food additives in foods and the implication this clause has on safety evaluation of additives. Put into perspective the benefits and risks of additives in foods. 3. List the common food-preservation techniques and...

Recommended readings

Albert, A., Selective Toxicity The Physio-Chemical Basis of Therapy, 6th ed., Chapman & Hall, London, 1979. Combs, G.F, Jr., The Vitamins Fundamental Aspects in Nutrition and Health, 2nd ed., Academic Press, New York, 1998. Meydani, M., Impact of aging on detoxification mechanisms, in Nutritional Toxicology, Kotsonis, F.N., Mackey, M., and Hjelle, J., Eds., Raven Press, New York, 1994, pp. 49-66. Netter, K.J., Toxicodietetics dietary alterations of toxic action, in New Concepts and...

Food Intolerance and Allergy

Mast Cell Diagram

According to some surveys, 20 to 25 of people in the U.S. are allergic to certain foods. Self-reported information based on changes in dietary habits to accommodate a food problem is likely to be mostly erroneous. Often, patients who say they have a food allergy avoid a food and never seek medical advice. Diagnosis of food allergies is overworked, poorly defined, and misused. There are many misconceptions about food allergies, such as understanding of the causes of food allergies and their...

History of food irradiation

Permanent Magnet Motor

As noted in Table 18.1, the benefits of ionizing radiation have been known since 1905. In addition to its potential to irradiation can be used to eliminate pests such as the screw worm fly, which preys on cattle, the Mediterranean fruit fly, and the tsetse fly, by the release of sterile insects. Worries about nuclear weapons, combinedwithanantiprogressideology, began to hinder food irradiation research afterthe war. Althoughthere wasatthat time an adequate supply of gamma rays, the high-energy,...

Nitrates nitrites and nitrosamines

Nitrates and nitrites in preserved meats (bacon, cold cuts) can prevent growth of Clostridium botulinum, the organism that can produce the potent botulinum toxin. However, nitrates and nitrites have been shown to have adverse effects, such as methemoglobinemia and carcinogenesis, the latter resulting from the formation of nitrosamines. Coincidentally, reduction of nitrate to nitrite is a common reaction for bacteria in the GI tract. Usually, the GI effect on nitrite is preceded by nitrate being...

Metabolism and Excretion of Toxicants

Leupeptin Plant

The amount of free plasma toxicant is a function of the toxicant's absorption, distribution, and elimination (Figure 9.1). In Chapter 8, a variety of factors that govern the absorption of toxicants in the gastrointestinal (GI) tract were discussed. This chapter focuses on factors that influence distribution and elimination of toxicants. Toxicants and other foreign compounds (xenobiotics) undergo metabolic transformation in the body. In many situations, the rate of metabolism is the primary...

Products of the maillard reaction

In the Maillard reaction, reducing sugars pentoses gt hexoses condensate with amino acids, producing a mixture of insoluble dark-brown polymeric pigments, termed melanoidins. Aldoses and ketoses react with aliphatic primary and secondary amines of amino acids and proteins to form -glycosides, which readily dehydrate to Schiff's base by the Maillard reaction Figure 19.4 . This is the basis for the well-known nonenzymatic browning reaction. In the early stages of the reaction, premel-anoidins are...

Risk characterization

With information about the dose-response and exposure features of the substance, the risk can be characterized. Risk characterization is the process of estimating the probable incidence of an adverse health effect to humans who are under the circumstances of exposure. When every data is available, risk characterization should be based on human data. However, frequently human data is fragmented, incomplete, or even lacking. Thus, extrapolations are made from dose-response relationships...