Human food-effect studies types

First of all, there is the scope of GLP as it is defined in the OECD Principles, and which states that GLP encompasses the non-clinical safety testing of test items contained in pharmaceutical products, pesticide products, cosmetic products, veterinary drugs as well as food additives, feed additives, and industrial chemicals. These test items are frequently synthetic chemicals, but may be of natural or biological origin and, in some circumstances, may be living organisms. The purpose of testing these test items is to obtain data on their properties and/or their safety with respect to human health and/or the environment. (OECD, 1998). GLP is thus applicable to safety studies in two major areas Effects on human health and on the environment. These two areas may share some types of studies that have to be conducted in order to test the safety of the respective test item, but other study types may exclusively be required for one or the other area. 

Assessment of whether a chemical has the potential to cause adverse effects in humans arises usually from direct observation of an effect in animals or humans, such as the acute poisoning episodes that have occurred when potatoes contain high levels of glycoalkaloids. Epidemiological studies have also been used to infer a possible relationship between intake of a particular type of food, or constituent of that food, and the potential to cause an adverse effect. Such observations led to the characterisation of the aflatoxins as human carcinogens. However, natural toxic substances that occur in plant foods have often been identified through observations in animals, particularly farm animals. It was observations of adverse effects in farm animals that led to the further characterisation of the phytoestrogens and the mycotoxins. In other instances, the concern arises from the chemical similarity to other known toxins. 

Studies which have attempted to demonstrate beneficial effects of consumption of organic foods can broadly be divided into two types (i) animal and human feeding studies with organic products, which include measures of changing... 

The hypothesis that dairy foods contain a cholesterol-lowering milk factor evolved from the observation that Maasai tribesmen of East Africa have low serum concentrations of cholesterol and a low incidence of cardiovascular disease in spite of their consumption of 4 to 5 liters/day of fermented whole milk (Mann and Spoerry 1974). Subsequently, sufficient amounts of yogurt, as well as unfermented milk (whole, lowfat, skim), were reported to exhibit a hypocholesterolemic effect both in humans and in laboratory animals in several studies (Mann 1977 Howard and Marks 1977, 1979 Nair and Mann 1977 Kritchevsky et al 1979 Richardson 1978 Hussi etal. 1981). However, not all investigators have observed a hypocholesterolemic effect of milk. This inconsistency may be explained in part by differences in the experimental design and in the specific type of dairy food used by investigators. 

There have been several epidemiological and several case reports inversely relating ascorbic acid intake from food to human cancer mortality. These studies are interesting, but may be confounded with the fact that the same ascorbic acid containing foods, namely fruits and vegetables, also contain large amounts of vitamin A and fiber. Both vitamin A and fiber have been inversely related to human cancer mortality and have been shown to inhibit several types of chemically-induced carcinogenesis in animals. Therefore, the possible anti cancer effect of ascorbic acid may be due to other factors. 

A special problem is the migration of low-molecular substances in materials used for food packaging. Here very stringent limitations on food contamination by compounds which are possibly harmful for health, are necessary. This complicated area is being studied carefully over the past decades, in order to establish for each type of additive or monomer residue what its effect on the human organism could be, and how much of such a substance could, under certain conditions, be expected to migrate from the packaging into the food. 

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