VitaminB6(pyridoxine)DerivativesserveascoenzymesinmanyintermediaryCheilosis,glossitis,dermatitis,peripheralreactionsneuropathy
Essentialfortransferanduseofone-carbonunitsinDNAMegaloblasticanemia,neuraltubedefectssynthesis *SeealsoChapter12.
Table 8.10 Selected Trace Elements and Deficiency Syndromes http://ebooksmedicine.net
PrimarySAMisacommoncauseofchildhooddeathsinpoorcountries.ThetwomainprimarySAMsyndromesaremarasmusandkwashiorkor.SecondarySAMoccursinthechronicallyillandinpatientswithadvancedcancer(asaresultofcachexia).
Kwashiorkorischaracterizedbyhypoalbuminemia,generalizededema,fattyliver,skinchanges,anddefectsinimmunity.Itiscausedbydietslowinproteinbutnormalincalories.
Marasmusischaracterizedbyemaciationresultingfromlossofmusclemassandfatwithrelativepreservationofserumalbumin.Itiscausedbydietsseverelylackingincalories—bothproteinandnonprotein.
Anorexianervosaisself-inducedstarvation;itischaracterizedbyamenorrheaandmultiplemanifestationsoflowthyroidhormonelevels.Bulimiaisaconditioninwhichfoodbingesalternatewithinducedvomiting.
VitaminsAandDarefat-solublevitaminswithawiderangeofactivities.VitaminCandmembersofthevitaminBfamilyarewater-soluble(
Table8.9 listsvitaminfunctionsanddeficiencysyndromes).
Excess adiposity (obesity) and excess body weight are associated with increased incidence of several of the most important diseases of humans, including type 2 diabetes, dyslipidemias, cardiovascular disease, hypertension, and cancer. It is a major public health problem in developed countries and an emerging health problem in developing nations, such as India. In the United States, obesity has reached epidemic proportions. The prevalence of obesity increased from 13% to 34% between 1960 and 2008, and as of 2015, 68.6% of Americans between 20 and 75 years of age were overweight as were 17% of the children. Globally, the World Health Organization (WHO) estimates that in 2015, 700 million adults were obese. The causes of this epidemic are complex but undoubtedly are related to societal changes in diet and levels of physical activity. Obesity is defined as a state of increased body weight, caused by adipose tissue accumulation, that is of sufficient magnitude to produce adverse health effects. How does one measure fat accumulation? Several high-tech methods have been devised, but for practical purposes the body mass index (BMI) is most commonly used. BMI is calculated as (weight in kilograms)/(height in meters)2, or kg/m2.
The BMI is closely correlated with body fat. BMIs in the range 18.5 to 25 kg/m2 are considered normal, whereas BMIs between 25 and 30 kg/m2 identify the overweight, and BMIs greater than 30 kg/m2, the obese. It is generally agreed that a BMI greater than 30 kg/m2 imparts a health risk. In the following discussion, for the sake of simplicity, the term obesity is applied to both the overweight and the truly obese.
The untoward effects of obesity are related not only to the total body weight but also to the distribution of the stored fat. Central, or visceral, obesity, in which fat accumulates in the trunk and in the abdominal cavity (in the mesentery and around viscera), is associated with a much higher risk for several diseases than is a condition of excess accumulation of fat in a diffuse distribution in subcutaneous tissue.