tually metabolizes excess amino acids to glucose,
glycogen, and fat. Though muscles in the body are
primarily protein structures, eating large quanti-
ties of protein does not build MUSCLEmass; the
body uses dietary protein only to supply the com-
ponents it needs to craft its own proteins. Protein
deficiency can be a health concern for vegans,
who must take extra care to eat a wide variety of
protein-rich plant-based foods to meet their pro-
tein needs.
MicronutrientsThe key groups of micronutrients are vitamins and
minerals, both of which facilitate the processes of
energy conversion within the body and are essen-
tial for life. Vitamins are organic substances useful
to the body only in their whole forms; cooking
and processing easily destroy many vitamins. Vita-
mins are also the source of many antioxidants,
biochemicals that remove free radicals (rogue
molecules that are the waste byproducts of metab-
olism) from the body. Researchers believe the
cumulative damage free radicals cause contributes
to many health conditions, including CVD and
cancer. Minerals are inorganic substances abun-
dant in the environment that enter food sources
directly (from the soil and water, as with plants)
or indirectly (from the plants that animals eat).
Minerals remain chemically unchanged from
sources to their uses in the body, even when they
bind with each other or with other substances.
Supportive Nutrients
Foods contain numerous substances that provide
supportive action for nutrients. Key among them
is the group called phytochemicals. Among the
most prominent of these are the carotenoids,
flavonoids, lignans, phenolic acids, phytosterols,
PHYTOESTROGENS, and protease inhibitors. Though a
number of phytochemicals have achieved recogni-
tion for their individual effects on health, the
strongest health benefits appear to come from
phytochemicals collectively. Health experts recom-
mend going straight to the source for supportive
nutrients, acquiring them through fresh fruits and
vegetables, legumes, and whole grains.
Other supportive nutrients include minerals
such as sulfur; amino acid derivatives such as carni-
tine and choline; and inositol, a substance the body
synthesizes from glucose. Sulfur is present in many
animal-based foods and occurs in the body as an
ingredient of proteins, some B vitamins, and some
hormones. Carnitine, choline, inositol, and numer-
ous similar substances act somewhat like vitamins
in the body, though the body synthesizes them.
See also AGING, NUTRITION AND DIETARY CHANGES
THAT OCCUR WITH; ANTIOXIDANT; BODY FAT PERCENTAGE;
CARBOHYDRATE LOADING; CELL STRUCTURE AND FUNC-
TION; DIET AND HEALTH; MINERALS AND HEALTH;
PHENYLKETONURIA (PKU); STARVATION; TRIGLYCERIDE
BLOOD LEVEL; TRIGLYCERIDES, DIETARY; VITAMINS AND
HEALTH.nutritional assessment A clinical evaluation of
an individual’s nutritional status, typically as part
of a ROUTINE MEDICAL EXAMINATIONor as a direction
of the diagnostic path when evaluating symptoms
that suggestNUTRITIONAL DEFICIENCY, MALNUTRITION,
gastrointestinal disorders, and systemic (body-
wide) disease. Routine nutritional assessment is
particularly important for the very young and the
very old.
A nutritional assessment begins with measure-
ment of height and body weight; physical exami-
nation to detect any signs or indications of
nutritional deficiency; and a discussion of the per-
son’s EATING HABITS, including the kinds and
amounts of food consumed over the course of a
day or a week. Basic BLOODtests can measure the
levels of key NUTRIENTSin the blood circulation or
nutrients the doctor suspects are deficient (such as
iron). The doctor may conduct further tests,
depending on the person’s health circumstances.
The doctor may also measure UPPER ARM CIR-
CUMFERENCE, TRICEPS SKINFOLD, WAIST CIRCUMFERENCE,
and hip circumference, factors that allow the doc-
tor to quantifiably assess BODY FAT PERCENTAGEas
well as loss of MUSCLEtissue in suspected nutri-
tional disorders. From these measurements the
doctor or nutritionist can calculate BODY MASS
INDEX(BMI), basal metabolic rate (BMR), resting
metabolic rate (RMR), and anticipated daily CALO-
RIErequirements based on the person’s lifestyle,
weight management needs, and unique health cir-
cumstances.
See also AGING, NUTRITION AND DIETARY CHANGES
THAT OCCUR WITH; DIET AND HEALTH; EXERCISE AND
HEALTH; METABOLISM.nutritional assessment 193