Nutrition Flashcards
starch
rate and extent of digestion and absorption in the small intestine varies
rapidly digestible starch include . Eg. cornflakes, crackers , white bread.
Slowly digestible starch Eg. rice, pasta , legumes etc.
Resistant starch
Carbohydrates
only mono and some disaccharides can be absorbed, mainly glucose, galactose and fructose.
end products include maltose, malt triose, dextrin etc
Lactose intolerance
Very common in adults and rare in children.
some people are partially intolerant and some are very intolerant
mainly avoid milk but some patients need to avoid foods that contain very small amounts of lactose
Glycaemia
the effect that food has on blood sugar levels after consumption is known as the glycaemic response
food rich in sugar has a higher glycaemic response than foods which are low in sugar.
foods rich in starch vary in glycaemic response depending on the nature of starch present
diets rich in slowly digest CHO may protect against chronic diseases
slowly digested starch results in a more modest glycaemic response
Absorption of triglycerides and cholesterol
- mixed with bile micelles and digestion of triglycerides by pancreatic lipase
- transport across the apical membrane of absorptive enterocytes
- mobilisation to chylomicrons for secretion into the lymph and then blood
Orlistat
- a potent and selective irreversible inhibitor of pancreatic lipase.
-reduces intestinal digestion of fat up to 30 - 40 % of total fat absorption
- available as an rx drug ad as an OTC preparation at lower doses
- Limited but significant effects in obese patients
- unpleasant side effects
Absorption of cholesterol
most important source of cholesterol available is in the liver.
large amounts are secreted from the liver in the bile and under the form of bile acid and reabsorbed
EZETIMIBE a new cholesterol drug inhibits NPCL1 transporters which is the main transporter responsible for the absorption of dietary cholesterol
Phytosterol / stanol
compounds isolated from plants and incorporated and concentrated into food products to lower cholesterol
However may impair vitamin D absorption and the clinical efficiency against CVD has not clearly been demonstrated
Fat
energy storage
released into circulation bound to serumalbumin
taken up by tissues and used for oxidation or as structural and functional lipid
Eating unsaturated fat is beneficial for health only if not overcooked and amount taken is not in excess
Avoid using vegetable oil rich in PUFA for frying
Using an oil rich in saturated fat, when consumed as part of a balanced diet is not necessary for harmful health
Proteins
- absorbed by intestines as amino acids or occasionally as dipeptides
Necessary for immune function, buffering, enzyme production, transport production
High protein intake may increase risk of osteoporosis (A condition when bone strength weakens and is susceptible to fracture. It usually affects hip, wrist or spine. )
Vitamin A
- mostly from animal products but large amounts in some veg
- needed for tissue development and differentiation.
fat soluble and stored in the liver
can be very toxic
overdose can take a long time to develop
main action in cell nucleus to interfere with gene transcription
Vitamin B
29 different subclasses
chemically unrelated enzymatic co factors
often occur together in similar foods
many have specific deficiency disease
Vitamin B12
- essential co enzyme, particularly for CNS function and in the maturation of developing RBC in bone marrow
Vitamin C
found in fruit and veg
for producing collagen, bone cartilage, teeth and maintaining capillaries
has antioxidant properties to help absorb iron
Vitamin D
used by body to regulate calcium, magnesium and phosphorus metabolism, important for immune system, activate specific nuclear receptor
