---
title: "Human nutrition"
chunk: 17/20
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"
---

==== Elderly Nutrition: Iron ====
Iron deficiency is prevalent among the elderly and is a significant contributor to anemia in this population. As people age, the body's ability to balance iron storage and supply diminishes, leading to this condition. Multiple factors contribute to iron deficiency in older adults, including reduced food intake, frequent medication use, gastrointestinal malabsorption, and occult bleeding. Malabsorption can also result in excessive iron accumulation, further complicating the issue. Age-related anemia may also be linked to increased levels of hepcidin, a hormone that reduces iron absorption in the intestine, leading to low iron levels.
The recommended daily intake of iron for both men and women is 8 mg, with an upper limit of 45 mg/day. According to the World Health Organization, hemoglobin levels below 12 g/dl in women and 13 mg/dl in men indicate anemia. The NHANES III survey found that anemia affects 10.2% of women and 11% of men over 65, with prevalence increasing with age. Low iron levels not only decrease quality of life but are also associated with depression, fatigue, cognitive impairment, and muscle wasting.
Dietary components significantly influence iron absorption; tannins and polyphenols in tea and coffee inhibit it, while Vitamin C enhances it. However, the interaction between iron and vitamin C can generate free radicals, particularly in cases of iron overload. In iron deficiency, vitamin C aids absorption. Aspirin use in the elderly, often for cardiovascular disease, is linked to lower serum ferritin levels. Iron deficiency can be managed through an iron-rich diet or supplementation. Severe iron deficiency anemia may require oral iron therapy, typically with 300 mg of ferrous sulfate containing 60 mg of elemental iron. For those who do not respond to oral treatment, intravenous iron infusion or iron chelation for iron overload may be necessary.

=== Clinical nutrition ===

On admission to intensive care unit, energy and protein requirements are calculated to determine the targets of nutritional therapy. Enteral nutrition (administering nutrition using a feeding tube) is started within 24 to 48 hours of admission with feeding targets increased every week. The risk of aspiration (inhalation of fluid or food particles while drinking or eating) can be reduced by elevating the head, using prokinetic agent, and using a chlorhexidine mouthwash. Although the presence of bowel sounds and the amount of gastric residual volume aspirated after feeding can be used to monitor the functionality of the gastrointestinal tract before feeding is started; starting nutritional therapy at this stage regardless of the functional status is feasible and safe within 36 to 48 hours of admission. Parenteral nutrition (administering of nutrition intravenously) should be started when enteral nutrition is not possible or sufficient or in high-risk subjects.
Before undergoing surgery, a subject should avoid long periods of fasting. Oral feeding should be established as soon as possible after surgery. Other aspects of nutrition such as control of glucose, reduction in risk factors that causes stress-related catabolism or impairment of gastrointestinal functions, and encourage early physical activity to encourage protein synthesis and muscle functions.

== History of human nutrition ==

Early human nutrition was largely determined by the availability and palatability of foods. Humans evolved as omnivorous hunter-gatherers, though the diet of humans has varied significantly depending on location and climate. The diet in the tropics tended to depend more heavily on plant foods, while the diet at higher latitudes tended more towards animal products. Analyses of postcranial and cranial remains of humans and animals from the Neolithic, along with detailed bone-modification studies, have shown that cannibalism also occurred among prehistoric humans.
Agriculture developed at different times in different places, starting about 11,500 years ago, providing some cultures with a more abundant supply of grains (such as wheat, rice and maize) and potatoes; and originating staples such as bread, pasta dough, and tortillas. The domestication of animals provided some cultures with milk and dairy products.
In 2020, archeological research discovered a frescoed thermopolium (a fast-food counter) in an exceptional state of preservation from 79 in Pompeii, including 2,000-year-old foods available in some of the deep terra cotta jars.

=== Nutrition in antiquity ===

During classical antiquity, diets consisted of simple fresh or preserved whole foods that were either locally grown or transported from neighboring areas during times of crisis.

=== 18th century until today: food processing and nutrition ===