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Most foods contain a mix of some or all of the nutrient classes, together with other substances. Some nutrients can be stored internally (e.g., the fat soluble vitamins), while others are required more or less continuously. Poor health can be caused by a lack of required nutrients or, in extreme cases, too much of a required nutrient.
A classification used primarily to describe nutrient needs of animals divides nutrients into macronutrients and micronutrients. Consumed in relatively large amounts ( grams or ounces ), macronutrients (carbohydrates, fats , proteins, water) are primarily used to generate energy or to incorporate into tissues for growth and repair.
Some can produce nutrients internally by consuming basic elements, while some must consume other organisms to obtain pre-existing nutrients. All forms of life require carbon, energy, and water as well as various other molecules. Animals require complex nutrients such as carbohydrates, lipids, and proteins, obtaining them by consuming other ...
Food is mainly composed of water, lipids, proteins, and carbohydrates. Minerals (e.g., salts) and organic substances (e.g., vitamins) can also be found in food. [4] Plants, algae, and some microorganisms use photosynthesis to make some of their own nutrients. [5] Water is found in many foods and has been defined as a food by itself. [6]
Selenium, which is an essential element for animals and prokaryotes and is a beneficial element for many plants, is the least-common of all the elements essential to life. [ 3 ] [ 63 ] Selenium acts as the catalytic center of several antioxidant enzymes, such as glutathione peroxidase , [ 11 ] and plays a wide variety of other biological roles .
Heterotrophic nutrition is a mode of nutrition in which organisms depend upon other organisms for food to survive. They can't make their own food like Green plants. Heterotrophic organisms have to take in all the organic substances they need to survive. All animals, certain types of fungi, and non-photosynthesizing plants are heterotrophic.
Metabolic water refers to water created inside a living organism through metabolism, by oxidizing energy-containing substances in food and adipose tissue. Animal metabolism produces about 107–110 grams of water per 100 grams of fat , [ 1 ] 41–42 grams of water per 100 g of protein , and 60 grams of water per 100 g of carbohydrate .
Animals have several characteristics that set them apart from other living things. Animals are eukaryotic and multicellular. [14] Unlike plants and algae, which produce their own nutrients, [15] animals are heterotrophic, [16] [17] feeding on organic material and digesting it internally. [18] With very few exceptions, animals respire aerobically.