Safety of Genetically Engineered Foods Approaches to Assessing Unintended Health Effects (2004) / Chapter Skim
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5 Adverse Impacts of Food on Human Health
5 Adverse Impacts of Food on Human Health
Pages 103-126
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From page 103... ...
Foods that could be modified in composition as a result of agricultural biotechnology, as defined in Chapter 1 and described in Chapters 2 and 3, are of interest because of the growing awareness that commonly consumed food constituents and complex mixtures can be beneficial or harmful to health. Estimates based on population-based research indicate that approximately one-third of preventable morbidity and mortality is of dietary origin and/or a consequence of low levels of physical activity.
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From page 104... ...
FOOD SAFETY HAZARDS IN FOOD PRODUCTS General Hazards from Foods A variety of safety hazards are associated with foods produced by any method. These can be categorized from greatest to least hazardous by their probability to cause an adverse health effect as: 1.
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From page 105... ...
In a recent report for the UK Food Standards Agency, two loads of organic corn meal were prevented from being sold to consumers because of excessive levels of fumonisins, a type of mycotoxin (FSA, 2003)
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From page 106... ...
. Nutrient Deficiencies, Toxicities, and Other Nutrient Imbalances Importantly, concerns regarding nutrient deficiencies and toxicities have been raised because of the acknowledged capability of genetic engineering to markedly change the composition of plant foods.
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From page 107... ...
. Expanding Definitions of Nutrient Deficiencies and Toxicities Other aspects of nutrient deficiencies and toxicities relevant to this discussion are the expanding definitions of nutrients and of their benefits and toxicities and the increased recognition of the roles of genetic variability in determining susceptibility to deficiency and toxicity states.
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From page 108... ...
Nutrient interactions also may influence nutrient urinary losses. Using calcium again for illustrative purposes, the acquisition of optimal bone mass in childhood and adolescence is dependent upon several factors, such as genetic endowment, activity, and diet (Bachrach, 2001)
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From page 109... ...
. Interference with assimilation may occur because of dietary amino acid imbalances that adversely affect the biological value of a protein or of a protein BOX 5-1 Potential Adverse Health Effects of Antinutrients Antinutrients are compounds in food that inhibit the normal uptake or utilization of nutrients.
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From page 110... ...
The mixture's biological value falls as the proportion of either protein source falls or rises in isonitrogenous diets. Furthermore, it is possible to add a protein with an imbalanced amino acid pattern to an otherwise adequate dietary protein intake and observe adverse effects on growth rates, as some amino acids are known to cause other types of toxicities when consumed in excessive amounts, and others to do so only when their intake is excessive relative to that of a structurally similar amino acid (i.e., amino acid antagonisms with excessive intakes of leucine relative to those of isoleucine)
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From page 111... ...
· Poisonous mushrooms · Poisonous plants such as foxglove and Senecio · Poisonous fish such as puffer fish Naturally occurring constituents of food that can cause illness (with unusually high consumption) · Cyanogenic glycosides in lima beans, cassava, and fruit pits · Phytoestrogens in ginseng Naturally occurring components of foods that can cause illness with usual consumption levels (only in susceptible consumers)
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From page 112... ...
Other foods contain naturally occurring toxicants that elicit adverse reactions only if the food is prepared in a manner that allows for the retention of a toxicant that is normally destroyed or discarded. For example, the lectins present in kidney beans are typically destroyed by thoroughly cooking kidney beans before eating them.
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From page 113... ...
The affected organ most likely to initiate systemic effects is the brain or, more broadly, the central nervous system. Toxins or toxicants that affect the circulatory system, blood and broader hematopoietic system, visceral organs, and the skin, in that order, also may have systemic effects, and those that affect muscle and bone generally are the least likely to have broader systemic consequences.
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From page 114... ...
Food Allergy True food allergies are predominantly, though not exclusively, diseases of childhood. True food allergies are abnormal immunological responses to a particular food or food component, usually a naturally occurring protein (Bohle and Vieths, 2004)
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From page 115... ...
Two types of immunological mechanisms are involved with true food allergies: immediate hypersensitivity reactions that are mediated by allergen-specific immunoglobulin (IgE) antibodies and delayed hypersensitivity reactions that are cell-mediated, primarily by intestinal lymphocytes and other immune cells (Taylor and Hefle, 2002)
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From page 116... ...
In the sensitization phase of the allergic response, the allergen-specific IgE antibodies bind to the surfaces of mast cells in various tissues and basophils in the blood. While the sensitization phase is symptomless, subsequent exposure to the specific allergen leads to an interaction between the mast cell/basophil-bound IgE antibodies and the allergen.
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From page 117... ...
. Also known as gluten-sensitive enteropathy and celiac sprue, celiac disease is associated with sensitivity to the ingestion of the primary protein fractions of wheat, rye, barley, and related grains, the so-called gluten fraction of wheat, and related protein fractions from the other grains (Skerritt et al., 1990)
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From page 118... ...
. Food Intolerance In contrast to true food allergies, food intolerances involve one of several mechanisms: anaphylactoid reactions, metabolic food disorders, or idiosyncratic reactions (Taylor and Hefle, 2002)
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From page 119... ...
are particularly attractive. Paradoxically, the more effective such modifications are, the likelier are unintended effects on the bioavailability of other dietary constituents, that is, changes that increase uptake of essential trace elements also may increase the bioavailability of unwanted contaminants, such as toxic heavy metals.
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From page 120... ...
. Two classic examples relevant to genetic variability and resulting adverse health effects related to food intake help to illustrate this source of potential concern: celiac disease and hemosiderosis.
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From page 121... ...
in the human genome. Most anticipate that monogenic traits will be relatively easy to identify by relating specific SNPs to specific phenotypes.
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From page 122... ...
In: Metcalfe DD, Sampson HA, Simon RA, eds. Food Allergy: Adverse Reactions to Foods and Food Additives.
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From page 123... ...
1998. Dietary Reference Intakes: A Risk Assessment Model for Establishing Upper Intake Levels for Nutrients.
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From page 124... ...
2003. What are the issues in addressing the allergenic potential of genetically modified foods?
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From page 125... ...
In: Metcalfe DD, Sampson HA, Simon RA, eds. Food Allergy: Adverse Reactions to Foods and Food Additives.
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