D–H
diet and health The effects foods and EATING
HABITShave on health and HEALTH RISK FACTORS. As
diet is the primary means by which the external
environment enters the internal environment of
the body, much research focuses on how diet
affects health in general as well as the risk for
numerous health conditions. The obvious correla-
tions are those between specific nutrient deficien-
cies, conditions such as BERIBERIand SCURVY. Other
health conditions that have major dietary connec-
tions are the diseases that claim the most lives and
cause the most disability among Americans: can-
cer, CARDIOVASCULAR DISEASE (CVD), DIABETES, OBE-
SITY, andOSTEOPOROSIS. Diet—what foods and how
much of them a person eats—has emerged as a
significant risk factor for these conditions.
On the whole, the body has a remarkable abil-
ity to use the substances it receives through diet to
conduct the functions of living. This ability in part
stems from the processes of METABOLISM that
reduce all NUTRIENTSto their absolute basic compo-
nents, amino acids and sugars that eventually
become GLUCOSE. The body’s numerous systems
then reassemble those components into the sub-
stances they require. In large part the body can
subsist in reasonable health on a marginal diet.
Eventually, however, the shortcomings become
problematic and begin contributing to health con-
ditions. For example, a diet low in fruits, vegeta-
bles, and whole grains lacks a consistent supply
of the vitamins and minerals the body needs to
manage its energy needs, maintain immune
functions, and regulate body activities. The
consequences of inefficient metabolism range
from molecular, which may include the accumula-
tion of free radicals or disruptions in protein
sequencing of GENETIC CODE, to overt disease such
as CVD.
Correlations between diet and disease are
sometimes difficult for researchers to quantify. For
example, people who eat a diet high in meats and
saturated fats have a higher incidence of COLON
cancer than people who eat a diet that is primarily
vegetarian and low in fat. The reasons for this are
imprecise, however, and likely represent an inte-
gration of factors of which diet is only one consid-
eration. Other correlations are more precise, such
as those that link high dietary saturated fat, high
CHOLESTEROL BLOOD LEVELS, and ATHEROSCLEROSIS.
Foods also appear to influence mood and behav-
ior, though again the precise mechanisms of these
interactions remain unknown.
Diet can bolster health as well. Supplying the
body with the nutrients it needs allows it to func-
tion with optimal efficiency. In such a state the
body’s own systems are fully active to resist dam-
age and respond promptly when injury or illness
occurs. Health experts believe lifestyle factors such
as diet and exercise have the ability to eliminate as
much as 85 percent of HEARTdisease, obesity, and
type 2 DIABETES, and reduce the risk for COLORECTAL
CANCER, STOMACH CANCER, and possibly BREAST CAN-
CERandPROSTATE CANCER.
See also ANTIOXIDANT; CANCER PREVENTION; CARDIO-
VASCULAR DISEASE PREVENTION; DIABETES PREVENTION;
FOOD SAFETY; HEALTHY PEOPLE 2010 ; LIFESTYLE AND
HEALTH; OBESITY AND HEALTH.enteral nutrition Nutritional supplementation or
replacement when a person cannot acquire the
necessary NUTRIENTSby eating, typically adminis-
tered via a nasogastric tube or surgically inserted
tube, commonly called a feeding tube. Long-term
enteral nutrition may become a QUALITY OF LIFE
issue or an end-of-life concern, especially for
those who become unable to make and express182