Generally, amino acids from animal proteins are best absorbed. Absorption sites
on the villi of the intestine are designated for specific amino acids. Sometimes an
overdose of one amino acid may interfere with or block the absorption of other needed
amino acids, so care must be used when consuming aa supplements. If an
essential
amino acid is missing from food, the cells begin to adjust their
activities almost immediately. On the amino acid scale of 0 to 100, with 100 representing
protein sources that are most readily digestible
and most perfectly
balanced,
egg
gets a 100. Ground beef, chicken products, fat-free milk and
tuna fish all score high. Plant proteins are
incomplete
and need
to be complimented to become complete.
The RDA for protein depends on body size and it is higher for children and pregnant and
lactating women to cover needs for building new tissue. For healthy adults, the RDA for
protein has been set at 0.8
grams for each kilogram of body weight. Approximately
10 to 35% of one's total calories should come from protein. Fifty to 60 grams of protein
a day should meet most individual's needs.
Two groups of foods in the My Plate Guide contribute high quality protein, including
the
dairy
group and the meat group. In addition, the vegetable and
grain groups contribute smaller amounts of protein. Protein rich foods carry with
them a characteristic array of vitamins and minerals , including vitamin B12 and
iron. However excess protein consumption (as in the case of a high meat diet or high
protein supplement use) can result in excessive deamination; this in turn can damage
kidneys, which need eliminate urea in the urine. Additionally after deamination (during
times of excessive protein intake) the cells use the fragments to make glycogen or fat.
If starving, the aa is deaminated and the fragment is used to make glucose (1 g yields
4 calories).
