Human diet odors

The safety limit between selenium, as an important micronutrient in human diet, and the appearance of toxic symptoms is quite small. The main symptoms from the uptake of an increased selenium quantity are dermatitis, vertigo, fragile nails, gastric disorders, hair loss, and garlic odor during breathing. 

The human taste threshold for PCP in drinking water is about 30 pg/L (USEPA 1980), a level far below the upper safe limit of 1.01 mg/L and near the no-observable-effect level of 21 pg/L (Table 23.7). Odor detection is not as sensitive as taste the odor threshold for PCP ranges from about 857 pg/L at 30°C, to 1600 pg/L at 20 to 22°C, to 12,000 pg/L at 60°C (USEPA 1980). It is not clear whether the determined organoleptic threshold values made the water undesirable or unfit for consumption (USEPA 1980). If fish and wildlife species of concern have PCP organoleptic thresholds that are similar to those of humans, or lower, will they too avoid contaminated habitats or diets ... 

Predators ignore sea hares because, like other mollusks without shells, they have chemicals that afford them the protection once given by a shell. (We saw earlier that a compound from a tropical sea hare is now a promising anticancer drug.) Many sea hares have an acrid or fetid odor that is distinctly unpleasant to humans. Their egg masses and their skin must be distasteful, because one exploratory bite is enough to convince a would-be assailant to look elsewhere for food. For some species, the deterrents responsible for these properties may come directly from their seaweed diet, but other species seem to synthesize these defenses for themselves. The evidence is mixed and confusing. 

The influence of odors such as perfumes and fragrances on human behavior is assumed to he acquired, and the responses elicited depend on the often complex previous social experiences. The response will be altered if a laboratory experiment eliminates contextual stimuli (Kirk-Smith and Booth, 1987). Social odors include those of the well-known security blankets in toddlers, familiarly scented bed sheets in new surroundings, and treating insomnia with mother s axillary odor on handkerchief. Removal of bad body odors (diet, metabolism defects) that disrupt interpersonal harmony appears to be universal. 

Edible fats and oils (lipids) are derived from plant, animal, and marine sources. Fats and oils differ in that fats are solids at normal room temperature whereas oils are liquids under similar conditions. Lipids are recognized as essential nutrients in both human and animal diets. They provide the most concentrated source of energy of any foods. The caloric value of lipids (9 kcal/g) exceeds twice that of proteins and carbohydrates (4 kcal/g). Lipids not only contribute to flavor, color, odor, and texture of foods, but also confer a feeling of satiety after eating. Lipids also act as carriers of fat-soluble vitamins, supply essential fatty acids, and increase the palatability of foods. Dietary fats are often categorized as visible or invisible ... 

The chemistry of olfactory cues, probably conveyed in complex secretions and involved in the performance of recognition summarized above, remains unknown. The odors of the human body are composed of at least 350 volatile compounds, the combinations of which indicate individuality, sex, emotional state or health [DOR 13], Environmental factors (related to feeding diet or skin microflora) or shared genetic characteristics may generate shared odor signatures across individuals. Along with these complex chemical signatures, we cannot yet exclude that crucial, universal, compounds shared by different species may also convey critical information. 

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