Are you getting
your protein?
In general,
proteins of animal origin contain adequate
amounts of the essential amino acids
and hence they are known as first class
proteins. On the other hand, many proteins
of vegetable origin are relatively deficient
in certain amino acids, notably lysine
and the sulphur-containing amino acids.
Mixtures of plant proteins can serve
as a complete and well-balanced source
of amino acids for meeting human physiological
requirements. However the combining
of right foods is necessary to obtain
the necessary levels of both the essential
or indispensable and conditionally indispensable
amino acids.
The essential amino
acid lysine is consistently at a much
lower concentration in all major plant-food
protein groups than in animal foods.
Since lysine is the limiting amino acid,
the addition of limited amounts of lysine
to cereal diets improves their protein
quality. Studies in Peru and Guatemala
have demonstrated that growing children
benefited by this addition. In addition,
the sulphur-containing amino acids are
distinctly lower in legumes and fruits
and threonine is lower in cereals compared
with amounts found in proteins of animal
origin.
Complementary Proteins
There are important differences
among and between food products of vegetable
and animal origin including the concentrations
of proteins and indispensable amino
acids that they contain. The concentration
of protein and the quality of the protein
in some foods of vegetable origin may
be too low to make them adequate, sole
sources of proteins. In some of the
poorer parts of the world, diets are
based predominantly on a single plant
(e.g. corn) and they frequently lead
to malnutrition.
Fortunately,
the amino acid deficiencies in a protein
can usually be improved by combining
it with another so that the mixture
of the two proteins will often have
a higher food value than either one
alone. For example, many cereals are
low in lysine, but high in methionine
and cysteine. On the other hand, soybeans,
Lima beans, and kidney beans are high
in lysine but low in methionine and
cysteine. When eaten together these
types of proteins gives a more favorable
amino acid profile.
Another example
would be the combination of soybean,
which is low in sulphur-containing amino
acids, with cottonseed, peanut and sesame
flour, and cereal grains, which are
deficient mainly in lysine. In general
oil-seed proteins, in particular, soy
protein, can be used effectively in
combination with most cereal grains
to improve the overall quality of the
total protein intake. A combination
of soy protein, which is high in lysine,
with a cereal that contains a relatively
good concentration of sulphur containing
amino acids results in a nutritional
complementation; the protein quality
of the mixture is greater than that
for either protein source alone.
Some examples of complementary food
proteins include:
- Beans and
corn (as in tortillas)
- Rice and
black-eyed peas
- Whole wheat or
bulgar
- Soybeans
- Sesame seeds
- Soybeans
- Peanuts
- Brown rice
- Bulgar wheat
This kind of supplementation
works when the deficient and complementary
proteins are ingested together or within
a few hours of each other. Various nutritional
responses are observed when two dietary
proteins are combined. These have been
classified by Bressani et al into one
of four types.
Type I
is an example where no protein complementary
effect is achieved. For example, this
occurs with combinations of peanut and
corn, where each of the protein sources
have a common and quantitatively similar
lysine deficiency and are both also
deficient in other amino acids.
Type II response is observed
when combinations are made of two protein
sources that have the same limiting
amino acid, but in quantitatively different
amounts. Corn and cottonseed flour,
for example, are both limiting in lysine
but cottonseed is relatively less inadequate
than is corn.
The third type
of response (Type III) demonstrates
a true complementary effect because
there is a synergistic effect on the
overall nutritive value of the protein
mixture; the protein quality of the
best mix exceeds that of each component
alone. This type of response occurs
when one of the protein sources has
a considerably higher concentration
of the most limiting amino acid in the
other protein. An example of this response,
based on studies in children, is observed
when corn and soy flour are mixed so
that 60% of the protein intake comes
from corn and the remainder from soya
protein.
Finally, the Type
IV response occurs when both protein
sources have a common amino acid deficiency.
The protein component giving the highest
value is the one containing a higher
concentration of the deficient amino
acid. Combinations of some textured
soy proteins and beef protein follow
this type of response.
These
nutritional relationships have been
determined from rat bio-assay studies.
However, the more limited results available
from human studies with soy and other
legumes confirm the applicability of
this general concept in human nutrition.
This knowledge helps us to understand
and evaluate how nutritionally effective
combinations of plant protein foods
can be achieved.
Even when combinations
of plant protein foods are used there
is still the concern of timing of ingestion
of complementary proteins. Is there
a need to ingest different plant proteins
at the same time, or within the same
meal, to achieve maximum benefit and
nutritional value from proteins with
different, but complementary, amino
acid patterns? This concern may also
extend to the question of the need to
ingest a significant amount of protein
at each meal, or whether it is sufficient
to consume protein in variable amounts
at different meals and even different
days as long as the average daily intake
meets or exceeds the recommended or
safe protein intakes.
According
to WHO (World Health Organization),
estimates of protein requirements refer
to metabolic needs that persist over
moderate periods of time. However, the
body does not store much protein outside
of a meager free amino acid pool, and
begins certain catabolic processes in
the post-absorptive phase making the
ingestion of regular amounts of protein
critical for maximizing the anabolic
effects of exercise. |
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CLIENT SUMMARY
A bodybuilding
e-commerce site needed to get found
on the search engines for their nutritional
products. We created a few articles
for the protein keyword, so that not
only he gets found, but also reduces
his bounce rate.
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