The Science and Pseudoscience of Hair Analysis

Laboratory analysis of hair can provide important clues to metabolic diseases and poisoning. A deficiency of zinc in the hair may indicate malnutrition. A deficiency of both magnesium and calcium is a sign of phenylketonuria (PKU), a hereditary defect in metabolism. A deficiency of calcium along with an excess of sodium may indicate cystic fibrosis.

Several poisons accumulate in the hair. Arsenic, cadmium, lead, and mercury, for example, can be 10 times as concentrated in hair as in blood or urine, and hair analysis can therefore aid in establishing a cause of death. DNA extracted from a single hair can be enough to implicate a suspect in a crime through the technique of DNA fingerprinting.

While hair analysis has valuable medical and legal applications, it is also exploited by health-food charlatans who charge high fees for hair

Saladin: Anatomy & I 6. The Integumentary I Text I I © The McGraw-Hill

Physiology: The Unity of System Companies, 2003 Form and Function, Third Edition

Hair Science 3rd Ediotion Hair Science 3rd Ediotion Hair Science 3rd EdiotionHair Science 3rd Ediotion

Figure 6.9 Basis of Hair Color and Texture. Straight hair (aand fa) is round in cross section while curly hair (cand d) is flatter. Blonde hair (a) has scanty eumelanin and a moderate amount of pheomelanin. Eumelanin predominates in black and brown hair (fa). Red hair (c) derives its color predominantly from pheomelanin. Gray and white hair (d) lack pigment and have air in the medulla.

analysis and special diets based on supposed deficiencies that the analysis "reveals." In reality, however, hair analysis has proven to be unreliable for assessing nutritional status or exposure to environmental toxins, and provides no meaningful basis for dietary recommendations.

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Essentials of Human Physiology

Essentials of Human Physiology

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