27.2 Biochem: BMI and protein-energy malnutrition Flashcards
What is the formula for body mass index?
Weight (kg)/(height in metres)^2
When does protein-energy malnutrition exist?
When there is an inadequate intake of macronutrients
What are the 2 categories of PEM?
Kwashiorkor (protein lack)
Marasmus (starvation)
What are the desirable % body fat ranges for men and women?
Men: 14-20% fat
Women: 19-30% fat
Above age 35, what are the health effects of a BMI=27
It adds little extra risk to health
What happens to fat distribution to males and females at puberty?
Females gain fat
Males lose fat
What is a morbidly obese BMI defined as?
What is a fatal BMI?
> 40 is morbidly obese
What happens to 3 pigs from the same litter when they are fed a diet that is:
unlimited good diet
small quantities of good diet
small quantities of good diet but with unlimited sugar
Unlimited: large pig
Small quantity: tiny pig
Small quantity + sugar: small pig (protein sparing but sugar=empty kJ)
How does Kwashiorkor occur?
What is the appearance?
Severe protein deficit (e.g. after weaning off breast milk in poorer countries)
Has oedema (due to lack of serum albumin) with some subcutaneous fat maintained
What is Marasmus due to?What is the appearance on a child?
Due to severe energy and protein deficit
Skin and bones appearance, little/no subcutaneous fat, protruding stomach
Why do many Nigerian/African countries have Kwashiorkor sufferers?
What toxic substance does this produce?
Aspergillus fungus on corn/peanuts
Aflatoxin
How is Aflatoxin metabolised? How is this toxic?
The P450 pathway (liver) converts aflatoxin to a reactive intermediate, epoxide
Epoxide attaches to DNA leading to cell death or cancer
What happens (biochemically) in the first three days of starvation? What about after this?
(e.g. what are we using for fuel in the absence of ingested fuel?)
First 3 days: muscle protein used for gluconeogenesis
After: fat breakdown established, glycerol used for gluconeogenesis
Fat used directly as a fuel and as ketones
What is the main problem leading to lasting neurological deficits during extended starvation?
Depletion of thiamine
What happens to the gut during starvation?
Progressive atrophy of the villi (gut is self digesting)
What is an ideal substance for refeeding? How might we alter this before administering it?
Milk! May need to be treated with lactase
use small amounts
What happens during the first four years of life in non-dairy consuming societies?
Lactase (chromosome 2) production drops 90%
How does the nitrogen balance change in starvation/burns victims/post-op patients/AIDs patients?
Why?
Negative balance (more excreted than consumed)
Due to the amino acid/protein breakdown
In cancer and AIDS, high levels of what causes cachexia? This is also called…
TNF-a (also called cachectin)
What is the prevalence of anorexia nervosa?
How does this prevalence differ in higher socio-economic backgrounds?
1-2% among schoolgirls (1/10th of this for males)
High prevalence in higher social classes
What is the correlation between saturated fat and heart disease?
What about unsaturated fat and omega 3s and heart disease?
No correlation
Reduced CV disease
