---
title: "Human nutrition"
chunk: 5/20
source: "https://en.wikipedia.org/wiki/Human_nutrition"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T03:55:25.210940+00:00"
instance: "kb-cron"
---

Cobalt as a component of the vitamin B12 family of coenzymes
Copper required component of many redox enzymes, including cytochrome c oxidase (see Copper in health)
Chromium required for sugar metabolism
Iodine required not only for the biosynthesis of thyroxin, but probably, for other important organs as breast, stomach, salivary glands, thymus etc. (see Iodine deficiency); for this reason iodine is needed in larger quantities than others in this list, and sometimes classified with the macrominerals; Nowadays it is most easily found in iodized salt, but there are also natural sources such as Kombu.
Iron required for many enzymes, and for hemoglobin and some other proteins
Manganese (processing of oxygen)
Molybdenum required for xanthine oxidase and related oxidases
Selenium required for peroxidase (antioxidant proteins)
Zinc required for several enzymes such as carboxypeptidase, liver alcohol dehydrogenase, carbonic anhydrase

==== Ultratrace minerals ====
Ultratrace minerals are an as yet unproven aspect of human nutrition, and may be required at amounts measured in very low ranges of μg/day. Many ultratrace elements have been suggested as essential, but such claims have usually not been confirmed. Definitive evidence for efficacy comes from the characterization of a biomolecule containing the element with an identifiable and testable function. These include:

Bromine
Arsenic
Nickel
Fluorine
Boron
Lithium
Strontium
Silicon
Vanadium

=== Vitamins ===

Except for vitamin D, vitamins are essential nutrients, necessary in the diet for good health. Vitamin D can be synthesized in the skin in the presence of UVB radiation. (Many animal species can synthesize vitamin C, but humans cannot.) Certain vitamin-like compounds that are recommended in the diet, such as carnitine, are thought useful for survival and health, but these are not "essential" dietary nutrients because the human body has some capacity to produce them from other compounds. Moreover, thousands of different phytochemicals have recently been discovered in food (particularly in fresh vegetables), which may have desirable properties including antioxidant activity (see below); experimental demonstration has been suggestive but inconclusive. Other essential nutrients not classed as vitamins include essential amino acids (see above), essential fatty acids (see above), and the minerals discussed in the preceding section.
Vitamin deficiencies may result in disease conditions: goiter, scurvy, osteoporosis, impaired immune system, disorders of cell metabolism, certain forms of cancer, symptoms of premature aging, and poor psychological health (including eating disorders), among many others.
Excess levels of some vitamins are also dangerous to health. The Food and Nutrition Board of the Institute of Medicine has established Tolerable Upper Intake Levels (ULs) for seven vitamins.

== Malnutrition ==

The term malnutrition addresses 3 broad groups of conditions:

Undernutrition, which includes wasting (low weight-for-height), stunting (low height-for-age) and underweight (low weight-for-age)
Micronutrient-related malnutrition, which includes micronutrient deficiencies or insufficiencies (a lack of important vitamins and minerals) or micronutrient excess
Overweight, obesity and diet-related noncommunicable diseases (such as heart disease, stroke, diabetes and some cancers).
In developed countries, the diseases of malnutrition are most often associated with nutritional imbalances or excessive consumption; there are more people in the world who are malnourished due to excessive consumption. According to the United Nations World Health Organization, the greatest challenge in developing nations today is not starvation, but insufficient nutrition – the lack of nutrients necessary for the growth and maintenance of vital functions. The causes of malnutrition are directly linked to inadequate macronutrient consumption and disease, and are indirectly linked to factors like "household food security, maternal and child care, health services, and the environment".

=== Insufficient ===
The U.S. Food and Nutrition Board sets Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for vitamins and minerals. EARs and RDAs are part of Dietary Reference Intakes. The DRI documents describe nutrient deficiency signs and symptoms.

=== Excessive ===
The U.S. Food and Nutrition Board sets Tolerable Upper Intake Levels (known as ULs) for vitamins and minerals when evidence is sufficient. ULs are set a safe fraction below amounts shown to cause health problems. ULs are part of Dietary Reference Intakes. The European Food Safety Authority also reviews the same safety questions and set its own ULs.

=== Unbalanced ===
When too much of one or more nutrients is present in the diet to the exclusion of the proper amount of other nutrients, the diet is said to be unbalanced. High calorie food ingredients such as vegetable oils, sugar and alcohol are referred to as "empty calories" because they displace from the diet foods that also contain protein, vitamins, minerals and fiber.

=== Illnesses caused by underconsumption and overconsumption ===

== Other substances ==

=== Alcohol (ethanol) ===
Pure ethanol provides 7 calories per gram. For distilled spirits, a standard serving in the United States is 1.5 fluid ounces, which at 40% ethanol (80 proof), would be 14 grams and 98 calories. Wine and beer contain a similar range of ethanol for servings of 5 ounces and 12 ounces, respectively, but these beverages also contain non-ethanol calories. A 5-ounce serving of wine contains 100 to 130 calories. A 12-ounce serving of beer contains 95 to 200 calories. According to the U.S. Department of Agriculture, based on NHANES 2013–2014 surveys, women ages 20 and up consume on average 6.8 grams/day and men consume on average 15.5 grams/day. Ignoring the non-alcohol contribution of those beverages, the average ethanol calorie contributions are 48 and 108 cal/day. Alcoholic beverages are considered empty calorie foods because other than calories, these contribute no essential nutrients.

=== Phytochemicals ===

Phytochemicals such as polyphenols are compounds produced naturally in plants (phyto means "plant" in Greek). In general, the term identifies compounds that are prevalent in plant foods, but are not proven to be essential for human nutrition, as of 2018. There is no conclusive evidence in humans that polyphenols or other non-nutrient compounds from plants confer health benefits, mainly because these compounds have poor bioavailability, i.e., following ingestion, they are digested into smaller metabolites with unknown functions, then are rapidly eliminated from the body.

== Intestinal microbiome ==