Nutrition science studies the
relationship between diet and states of health and disease.
Dieticians are Health professionals who are specialized
in this area of expertise, highly trained to provide
safe, evidence-based dietary advice and interventions.
There is a spectrum ranging from malnutrition to optimal
health, including many common symptoms and diseases
which can often be prevented or alleviated with better
nutrition.
Deficiencies, excesses and and imbalances in diet can
produce negative impacts on health, which may lead to
diseases such as scurvy, obesity or osteoporosis, as
well as psychological and behavioral problems. Moreover,
excessive ingestion of elements that have no apparent
role in health, (e.g. lead, mercury, PCBs, dioxins),
may incur toxic and potentially lethal effects, depending
on the dose. The science of nutrition attempts to understand
how and why specific dietary aspects influence health.
Nutrition science seeks to explain
metabolic and physiological responses of the body to
diet. With advances in molecular biology, biochemistry,
and genetics, nutrition science is additionally developing
into the study of integrative metabolism, which seeks
to connect diet and health through the lens of biochemical
processes.
The human body is made up of chemical compounds such
as water, amino acids (proteins), fatty acids (lipids),
nucleic acids (DNA/RNA), and carbohydrates (e.g. sugars
and fiber). These compounds in turn consist of elements
such as carbon, hydrogen, oxygen, nitrogen, and phosphorus,
and may or may not contain minerals such as calcium,
iron, or zinc. Minerals ubiquitously occur in the form
of salts and electrolytes. All of these chemical compounds
and elements occur in various forms and combinations
(e.g. hormones/vitamins, phospholipids, hydroxyapatite),
both in the human body and in organisms (e.g. plants,
animals) that humans eat.
The human body necessarily comprises
the elements that it eats and absorbs into the bloodstream.
The digestive system, except in the unborn fetus, participates
in the first step which makes the different chemical
compounds and elements in food available for the trillions
of cells of the body. In the digestive process of an
average adult, about seven litres of liquid, known as
digestive juices, exit the internal body and enter the
lumen of the digestive tract. The digestive juices help
break chemical bonds between ingested compounds as well
as modulate the conformation and/or energetic state
of the compounds/elements.
However, many compounds/elements
are absorbed into the bloodstream unchanged, though
the digestive process helps to release them from the
matrix of the foods where they occur. Any unabsorbed
matter is excreted in the feces. But only a minimal
amount of digestive juice is eliminated by this process;
the intestines reabsorb most of it; otherwise the body
would rapidly dehydrate; (hence the devastating effects
of persistent diarrhea).
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