The review will encompass the following points: A brief introduction to the role of the gut flora in the toxicology of ingested food components, contaminants, and additives, including known pathways of activation and detoxication of foreign compounds and the implication of the flora in enterohepatic circulation of xenobiotics. The advantages and disadvantages of the various methods of studying the gut flora (classical bacteriological techniques, metabolic and enzymological methods) will be critically discussed with special reference to their relevance to dietary, toxicological, and biochemical studies. Sources of nutrients available to the gut flora will be described including host products (mucus, sloughed mucosal cells, hormones, proteins) and exogenous nutrients derived from diet. An account of the problems involved in studies of dietary modification with special reference to the use of stock laboratory animal diets, purified diets, and human dietary studies. The influence of dietary modification on the flora will be assessed on the basis of changes in numbers and types of bacteria and their metabolic activity, drawing on data from human and animal studies. The effects of manipulation of the quantity and quality of protein, fat, and indigestible residues (fiber) of the diet will be described together with their possible implications for toxicity of ingested compounds.

The Effect of Diet on the Mammalian Gut Flora and Its Metabolic Activities

DISCLAIMER The use of company or product name(s) is for identification only and does not imply endorsement by the Agency for Toxic Substances and Disease Registry. This edition supersedes any previously released draft or final profile. Toxicological profiles are revised and republished as necessary. For information regarding the update status of previously released profiles, contact ATSDR at: Toxicological Profiles are a unique compilation of toxicological information on a given hazardous substance. Each profile reflects a comprehensive and extensive evaluation, summary, and interpretation of available toxicologic and epidemiologic information on a substance. Health care providers treating patients potentially exposed to hazardous substances will find the following information helpful for fast answers to often-asked questions. Chapter 1: Public Health Statement: The Public Health Statement can be a useful tool for educating patients about possible exposure to a hazardous substance. It explains a substance's relevant toxicologic properties in a nontechnical, question-and-answer format, and it includes a review of the general health effects observed following exposure. Chapter 3: Health Effects: Specific health effects of a given hazardous compound are reported by type of health effect (death, systemic, immunologic, reproductive), by route of exposure, and by length of exposure (acute, intermediate, and chronic). In addition, both human and animal studies are reported in this section. NOTE: Not all health effects reported in this section are necessarily observed in the clinical setting. Please refer to the Public Health Statement to identify general health effects observed following exposure. The following additional material can be ordered through the ATSDR Information Center: Case Studies in Environmental Medicine: Taking an Exposure History—The importance of taking an exposure history and how to conduct one are described, and an example of a thorough exposure history is provided. Other case studies of interest include Reproductive and Developmental viii HEXACHLOROCYCLOHEXANE Hazards; Skin Lesions and Environmental Exposures; Cholinesterase-Inhibiting Pesticide Toxicity; and numerous chemical-specific case studies. Managing Hazardous Materials Incidents is a three-volume set of recommendations for on-scene (prehospital) and hospital medical management of patients exposed during a hazardous materials incident. Volumes I and II are planning guides to assist first responders and hospital emergency department personnel in planning for incidents that involve hazardous materials. Volume III— Medical Management Guidelines for Acute Chemical Exposures—is a guide for health care professionals treating patients exposed to hazardous materials. Fact Sheets (ToxFAQs) provide answers to frequently asked questions about toxic substances. The National Center for Environmental Health (NCEH) focuses …

Toxicological profile for alpha-, beta-, gamma, and delta-hexachlorocyclohexane

Under current climate trends, spring ice breakup in Hudson Bay is advancing rapidly, leaving polar bears (Ursus maritimus) less time to hunt seals during the spring when they accumulate the majority of their annual fat reserves. For this reason, foods that polar bears consume during the ice-free season may become increasingly important in alleviating nutritional stress from lost seal hunting opportunities. Defining how the terrestrial diet might have changed since the onset of rapid climate change is an important step in understanding how polar bears may be reacting to climate change. We characterized the current terrestrial diet of polar bears in western Hudson Bay by evaluating the contents of passively sampled scat and comparing it to a similar study conducted 40 years ago. While the two terrestrial diets broadly overlap, polar bears currently appear to be exploiting increasingly abundant resources such as caribou (Rangifer tarandus) and snow geese (Chen caerulescens caerulescens) and newly available resources such as eggs. This opportunistic shift is similar to the diet mixing strategy common among other Arctic predators and bear species. We discuss whether the observed diet shift is solely a response to a nutritional stress or is an expression of plastic foraging behavior.

/pdf/what-to-eat-now-shifts-in-polar-bear-diet-during-the-ice-1kcrbk2q9j.pdf

What to eat now? Shifts in polar bear diet during the ice‐free season in western Hudson Bay

1. A semi-synthetic diet, the semi-synthetic diet plus pectin, and a stock diet were fed to rats, and three metabolic functions of the caecal bacteria (reduction of amaranth, p-nitrobenzoic acid and nitrate) were measured in vitro. 2. No consistent differences were noted between diets for the reduction of amaranth and p-nitrobenzoic acid. 3. No consistent differences in nitrate reductase activity were noted for rats maintained on a stock diet or a fibre-free diet. However, the addition of 5% pectin to the latter diet resulted in a several-fold increase in nitrite production. 4. This increased nitrite production in vitro was associated with methaemoglobinaemia following the oral administration of nitrate to rats fed the diet containing pectin. Animals receiving the basal fibre-free diet were unaffected by nitrate.

C.J. Chadwick

Papers

Enhanced pesticide metabolism, a previously unreported effect of dietary fibre in mammals