Phytic acid
Phytic acid, the hexaphosphoric ester of myo-inositol, is a strong acid. It forms insoluble salts with many types of bivalent and tervalent heavy metal ions. In that way, phytic acid reduces the availability of many minerals and essential trace elements. Phytic acid has been shown to have a negative effect on iron absorption in humans. The absorption of iron depends mainly on the levels in the iron pools, the amount and the chemical form ingested, and the presence of ascorbic acid. Ferric...
Oxalic acid
Oxalic acid HOOC-COOH can induce toxic as well as antinutritive effects. To humans, it can be acutely toxic. However, it would require massive doses of 4 to 5 g to induce any toxic effect. The oxalic acid levels usually found in food, however, are no cause for concern. This section, discusses the presence of oxalic acid in food in relation to its antinutritive effects. Like phytic acid, oxalic acid reduces the availability of essential bivalent cations. Oxalic acid is a strong acid and, with...
Aspartame
Aspartame is another artificial sweetener. It is a dipeptide, consisting of L-aspartic acid and the methyl ester of L-phenylalanine. In the gastrointestinal tract, aspartame undergoes complete hydrolysis into its three components aspartic acid, phenylalanine, and methanol Figure 9.6 . Although aspartame has been approved the ADI is set at 50 mg kg body weight per day as a sweetener in many countries, there are still some toxicological aspects under consideration. A small number of urticarial...
Biogenic amines
Natural toxins also include certain amines which can be of plant as well as of microbial origin. The latter source is dealt with in Section 2.3.3. The most important biogenic amines found in plants are listed in Table 2.3. The dietary intake of biogenic amines may pose risks. A well-known harmful effect of all three of the phenethylamines, dopamine, norepinephrine, and tyramine is hypertension. The risk is greater when combinations of biogenic amines and monoamine oxidase MAO inhibitors are...
Introduction Tpa
Early man, in pre-Neolithic times, hunted for meat and gathered what food he could. Just like modern man, he had to balance his requirements of energy, protein, and other essential nutrients. He also tried to avoid consumption of toxic factors naturally present in certain foods, presumably achieved by careful observation and, of course, by trial and error. Clearly, it was possible for the fit to survive such a lifestyle. The population increased and eventually agricultural methods were adopted....
Introduction Xcm
The increasing demand for ready-to-eat foods, snacks, and a continuous assortment of foodstuffs, even if they are out of season, and the change in lifestyle that has taken place during the last centuries, have led to an increase in the use of food additives. Food additives are substances that man adds to food intentionally to provide protection against contamination with microorganisms, to prevent oxidative deterioration of oils, fats, and shortenings, to keep food appealing and tasteful, and...
Antithiamine factors
A second group of antivitamins is the antithiamine factors. They interact with vitamin Bv also known as thiamine. Antithiamine factors can be distinguished as thiaminases, tannins, and catechols. The interaction with vitamin B1 can lead to serious neurotoxic effects as a result of vitamin B1 deficiency. Normally, antithiamine factors pose no appreciable risk to humans. They only cause thiamine deficiency in people whose diet is already low in thiamine. Thiaminases are found in many fish...
Lectins
Lectins is the general term for plant proteins that have highly specific binding sites for carbohydrates. The majority of the lectins are glycoproteins. A carbohydrate-free lectin occurs in jack beans concanavalin A . The lectin in kidney beans is probably a lipoprotein. The mode of action of lectins may be related to their ability to bind to specific cell receptors in a way comparable to that of antibodies. They can agglutinate red blood cells. Therefore, they are also called hemagglutinins....
Safrole
This substance is a typical member of a series of propenylbenzenes. These also include methyleugenol and estragole. The propenylbenzenes are natural and synthetic flavoring agents. Sassafras, containing high levels of safrole, used to be added to sarsaparilla root beer. Nowadays, safrole is still present in the diet as a minor component of various herbs and spices, e.g., cloves. Safrole and related substances have been shown to be carcinogenic. Possible metabolic activation routes are...
Summary Vkd
It is very important when dealing with adverse food reactions to use generally accepted terminology this will avoid misunderstandings. As this chapter illustrates, many mechanisms underlying food allergy and food intolerance still have to be elucidated. It is often difficult to give an accurate diagnosis of food allergy. This is largely due to the limited reliability of the diagnostic means. Good therapy can only be started if the diagnosis is clear herein lies an important problem. If...
Basic requirements of risk evaluation and standard setting
17.2 Nutritional value of the food supply 17.2.1 Nutritional considerations 17.2.2 Nutritional evaluation of foods 17.2.3 Strategy for nutritional testing 17.2.4 Design of nutritional studies 17.3 Toxicological factors affecting food safety 17.3.1 Safety assessment of new food components 17.3.2 Methods of hazard identification 17.3.4 Harmonization of safety testing procedures 17.4 Setting tolerable intake levels for natural toxins and food contaminants 17.4.1 Assessment of toxicological risks...
Preservatives
Preservatives are added to decrease the degradation rate of foods during processing and storage. They include antioxidants, antimicrobials and antibrowning agents. 5.2.3.1 Antioxidants Antioxidants primarily prevent or inhibit autoxidation of fatty acids see also Part I, Chapter 6 in food products and, consequently, the development of rancidity and off-flavor. They are especially useful in preserving dry and frozen foods for long periods of time. The major antioxidants for the protection of...
Halogenated Aromatic Hydrocarbons
10.3.2.1 Polychlorinated biphenyls The polychlorinated biphenyl PCB content of animal food is decreasing in recent years. This is due to the ban on the use of PCBs. Notwithstanding, the levels of PCBs can still be high because of their low biodegradability. - induction of phase I i.e., oxidases, reductases as well as of phase II i.e., conjugases xenobiotic-metabolizing enzymes The most prominent effect in humans is persistent chloracne on the skin of the head and chest. This skin disease is...
Reference and reading list Ken
Ashwell, M., How safe is our food A report of the British Nutrition Foundation's eleventh annual conference, in J. Royal College Phys. 24 3 , 233-237, 1990. Concon, J.M., Food Toxicology in two parts . New York, Marcel Dekker Inc., 1988. Fiedler, H., H. Frank, O. Hutzinger, W. Partzefall, A. Riss, and S. Safe Dioxin '93, in Organohalogen Compounds. Vol. 13 and 14, 1993. Friberg, L., C.G. Elinder, T. Kjellstrom and G.F. Nordberg, Cadmium and Health a Toxicological and Epidemiological Appraisal....
T Bruggink
14.2 General aspects of allergy and intolerance 14.2.2.1 Types of hypersensitivity 14.2.2.1.1 Type I hypersensitivity 14.2.2.1.2 Type II hypersensitivity 14.2.2.1.3 Type III hypersensitivity 14.2.2.1.4 Type IV hypersensitivity 14.2.2.2 Defense mechanisms in the digestive tract 14.2.4.2.4 Monosodium glutamate ve-tsin 14.3 Clinical aspects of food allergy and food intolerance 14.4 Summary Reference and reading list
Hazard analysis at critical control points
The introduction in the 1970s of the Hazard Analysis at Critical Control Points HACCP see Part 3, Chapter 21, Section 21.3 concept has marked a change in the philosophy with regard to the microbiological quality assurance of food. This concept provides a means for identifying the microbiologically important stages in food processing and the means to control them. Introduction of this system starts with a detailed analysis of the hazards associated with the manufacture, distribution, and use of...
Central stimulants
For most people the everyday diet contains a considerable amount of stimulants. These substances increase the state of activity of the nervous system. A particular class of stimulants is the methylxanthines. They include caffeine, theophylline, and theobromine. Caffeine is found in coffee beans, tea leaves, cocoa beans, and colanuts. In our diet the primary source of caffeine, however, is coffee one cup of coffee is estimated to contain 100 to 150 mg of caffeine. The caffeine content of cola...
Tartrazine
Tartrazine is a yellow synthetic azo dye. Several clinical symptoms have been attributed to tartrazine, including asthma, hyperactivity of children, and urticaria hives . Much attention has been paid to the induction of effects in asthma patients after the intake of tartrazine. A number of studies reported a high incidence of intolerance of tartrazine among aspirin acetylsalicylic acid -intolerant asthmatics. On the whole, however, little evidence has been found against the use of tartrazine in...
Nonnutritive natural food components of important toxicological relevance
11.2.1.1 a-Aminopropionic acid derivatives a-Aminopropionic acid derivatives occur in peas of certain Lathyrus species. These substances are known to cause skeletal malformations osteolathyrism and neurotoxic effects Table 11.1 Nonnutritive natural food components that have given or still give rise to concern fatty acid rapeseed Cyclopropane and cyclopropene Carotatoxin poly-acetylene carrots Thujone a- and P- monoterpene spices component of absinthe liqueur D-limonene monoterpene citrus oil...
Antinutritives
3.2 Type A antinutritives antiproteins 3.3 Type B antinutritives antiminerals 3.4 Type C antinutritives antivitamins 3.5 Summary Reference and reading list
Antipyridoxine factors
A variety of plants and mushrooms contain pyridoxine a form of vitamin B6 antagonists. The antipyridoxine factors have been identified as hydrazine derivatives. Linseed contains the watersoluble and heat-labile antipyridoxine factor linatine. Linatine is y-glutamyl-1-amino-D-proline. It readily undergoes hydrolysis to the hydrazine derivative, 1-aminoproline, the actual antipyridoxine factor Figure 3.4 . Antipyridoxine factors have also been found in wild mushrooms, the common commercial edible...
Glucosinolates 1
A variety of plants contain a third group of antiminerals, the so-called glucosinolates, a class of thioglucosides, whose general structure is shown below. Many glucosinolates are goitrogenic. Three types of goiter are distinguished cabbage goiter struma , brassica seed goiter, and legume goiter. Cabbage goiter can be induced by the excessive consumption of cabbage. It seems that cabbage goitrogens inhibit iodine uptake by directly affecting the thyroid gland. Cabbage goiter can be treated by...
Summary 1
Antinutritives induce their toxic effects indirectly by causing nutritional deficiencies or by obstructing the utilization or functioning of nutrients, mainly proteins, minerals, and vitamins. Especially in the case of marginal nutritional status or malnutrition, the effects of antinutritives can become manifest. The majority of antinutritives are of natural origin. They are distinguished as three types antiproteins, antiminerals, and antivitamins. Antiproteins interfere with the digestion of...
Natural contaminants
Natural contaminants can also originate from biological systems different from those in which they occur. There are three important sources. First, raw materials of plant origin can become contaminated if they are mixed with toxic non-nutritive plant species. Secondly, raw materials of animal origin, mainly fish and milk, can also become contaminated if the animal has ingested toxic substances of natural origin. Thirdly, contaminants of natural origin can be the products of microorganisms. This...
Microbial toxins 2331 Introduction
Section 2.3.3 deals with the way in which toxic substances produced in food and feed by microorganisms enter the pathway from raw material to consumer. Microorganisms are ubiquitous. Any environment supporting higher organisms contains microorganisms too, while the converse is not true. Absence of microorganisms in an environment indicates that special or unusual conditions have occurred, such as heating and filtration for sterilization or preservation. During food production, raw food...