subside. Cardiovascular symptoms generally
improve within 24 hours, though underlying
damage to the HEART may be permanent and
require subsequent treatment. Neurologic and
musculoskeletal symptoms may take several
months to completely resolve. Dry beriberi gener-
ally resolves without residual complications except
in the most severe cases, in which there may be
permanent peripheral neuropathy (damage to the
PERIPHERAL NERVES). Untreated beriberi is fatal, usu-
ally a result of cardiovascular collapse.
Maintenance therapy with vitamin B supple-
mentation helps prevent RECURRENCE, especially
in people who are not likely to receive adequate
B vitamins from dietary sources. Most people
who have thiamine deficiency are also deficient
in other B vitamins and should take a vitamin
B complex supplement product. People who
have gastrointestinal disorders that interfere with
their ability to absorb thiamine, such as PEPTIC
ULCER DISEASE, may require ongoing thiamine
injections.
Risk Factors and Preventive MeasuresThe sole risk factor for beriberi is inadequate con-
sumption of dietary thiamine. Accordingly, main-
taining adequate dietary consumption of foods
that contain B vitamins prevents beriberi in most
people. Food sources of thiamine include lean
meats (notably pork), legumes, watermelon, acorn
squash, and whole grains and whole grain prod-
ucts. Grain products such as breads and cereals
produced in the United States are fortified with B
vitamins, including thiamine. Highly refined and
processed foods, especially white rice and white
bread, contain minimal amounts of B vitamins,
including thiamine, unless they are fortified. B
complex vitamin supplements help ensure ade-
quate intake. B vitamins are water-soluble so
there is no risk for OVERDOSE.
See also ANEMIA; MALNUTRITION; NUTRITIONAL DEFI-
CIENCY; NUTRITIONAL NEEDS; PELLAGRA; RICKETS;
SCURVY; VITAMINS AND HEALTH.
calorie A unit of measure that denotes heat
consumption. In nutrition and exercise, calories
represent a measure of energy exchange. The
calories in foods represent energy the body takes
in, and the calories assigned to physical exertion
represent energy the body expends. Recom-
mended daily calorie intake guidelines represent
the amount of energy a typical adult requires to
carry out the activities of normal living. Taking in
more calories than one expends results in weight
gain (the body stores extra calories as fat), and
expending more calories than one consumes
results in weight loss (the body draws from stored
energy to meet its needs). The steady state of
weight maintenance occurs when there is a rela-
tive balance between the calories that enter the
body and the calories the body uses.
See alsoMETABOLIC EQUIVALENT(MET); NUTRIENTS;
NUTRITIONAL NEEDS.carbohydrate intolerance An enzyme deficiency
that results in the body’s inability to metabolize
one or more forms of carbohydrate. The most
common form of carbohydrate intolerance is LAC-
TOSE INTOLERANCE, which affects up to 50 million
Americans and results from a deficiency of the
enzyme lactase. Other forms of carbohydrate
intolerance are much less common though may
result from deficiencies of maltase (necessary to
metabolize maltose) and sucrase (also called iso-
maltase, necessary to metabolize sucrose).
The enzyme deficiencies responsible for carbo-
hydrate intolerance may be congenital (absent
from birth), acquired through a natural decline in
DIGESTIVE ENZYMESthrough aging, or as a conse-
quence of gastrointestinal disorders such as CELIAC
DISEASE. RADIATION THERAPYand CHEMOTHERAPYtreat-
ments for cancer also can affect the cells that pro-
duce the various enzymes, resulting in enzyme
depletion and intolerance of the corresponding
carbohydrate.
The symptoms of carbohydrate intolerance
often include abdominal cramping, flatulence
(gas), and DIARRHEA. Children may fail to gain
weight or grow appropriately. The diagnostic path
may include an oral carbohydrate challenge, in
which the person drinks a solution containing the
suspect carbohydrate. BLOODsamples taken at cer-
tain intervals measure the amount of the sugar
form present in the blood circulation. Because lac-
tose intolerance results INexcessive hydrogen gas
production, breath tests to measure hydrogen con-
centrations in the lungs are often diagnostic for
lactose intolerance.180 Nutrition and Diet