Download Name: # More on Protein Urea Excretion During fasting when blood

Name:
#
More on Protein
Urea Excretion
During fasting when blood glucose level and liver glycogen level are both low, the body makes glucose
from noncarbohydrate sources, this process is called
removal of amino group from
. This requires the
amino acids. This process (
) produces
ammonia, which is toxic to cells. The liver converts ammonia into
, a less toxic substance.
CO2
(NH2)2CO + glucose
H3N – CH – COOH
|
R
glucose + NH3
ammonia
Nitrogen Balance
Health professions often assess one’s protein status by comparing the p
and n
l
i
(protein loss) in body secretions.

Nitrogen balance: protein intake = nitrogen loss

Negative nitrogen balance: protein intake < / = / > nitrogen loss (people with kidney failure)

Positive nitrogen balance: protein intake < / = / > nitrogen loss (growing children)
Protein Turnover
The body recycles amino acids from “retired” proteins by breaking them down and resynthesizing them.
Dietary amino acids and amino acids from protein degradation, or
, are both released into
what is called the body’s
. New proteins are
(free)
synthesized from a mixture of “new” and “recycled” amino acids.
Protein Consumption
You need to consume adequate amounts of essential amino acids to


Where could you find how much of each essential amino acid you should eat every day?
There is no compelling evidence that high intakes of any of the essential amino acids pose known health
risks, the IOM did not establish
for them.
People who need more proteins
1. Males (compared to females)
2. Infants and teenagers
3. Pregnant/Lactating women
4. Recovering patients
5. Athletes
Vegetarian Diets
 Lacto-ovo-vegetarians
 Lactovegetarians
 Vegans
In general, a well-balanced lacto-ovo- or lactovegetarian diet can easily provide adequate protein, energy,
and micronutrients. Dairy products and eggs are convenient sources of high-quality protein and many
vitamins and minerals. However, because meat is often the primary source of bioavailable (what does it
mean?) iron, eliminating it can lead to iron deficiency. Furthermore, vegans may be at increased risk of
being deficient in several micronutrients, including calcium, zinc, iron, and vitamin B12. This risk increases
further during pregnancy, lactation, and periods of growth and development such as infancy and adolescence.
Thus, it is especially important that vegetarians consume sufficient amounts of plant-based food rich in these
micronutrients.
Because some types of vegetarian diets pose certain nutritional risks, it is important to follow special dietary
strategies if you decide to make this dietary choice. The MyPlate food guidance system specifically
recognizes protein, iron, calcium, zinc, and vitamin B12 as nutrients for vegetarians to focus on, making
specific recommendations as to how to get adequate amounts. In addition, it is pointed out that some meat
replacements, such as cheese, can be very high in calories, saturated fat, and cholesterol. Thus lower-fat
versions should be chosen, and they should be consumed in moderation. The following comments and
suggestions are offered to help ensure optimal health in individuals who choose to become vegetarians.
Note that these recommendations are especially pertinent to vegans.






Select sources of protein that are naturally low in fat (skim milk and legumes)
Minimize the amount of high-fat cheese used as meat replacements
Calcium-fortified soy-based beverages provide calcium in amounts similar to milk and are usually
low in fat and do not contain cholesterol
Add vegetarian meat substitutes (tofu) to soups and stews to boost protein without adding saturated
fat and cholesterol
Consider eating out at Asian or Indian restaurants, as they often offer a varied selection of highprotein vegetarian dishes
Be mindful of getting enough vitamin B12 because this vitamin is naturally found only in animal
products, fortified foods, or dietary supplements for vegetarians
The key to a healthy diet, vegetarian or not, is to enjoy a wide assortment of foods and to consume them in
moderation. Because no single food provides all the nutrients the body needs, eating a variety of foods can
help ensure that vegetarians get the necessary nutrients and other substances that promote good health.