All about fruitarianism with a long-term fruitarian, Lena
A vitamin is an organic compound and a vital nutrient that an organism requires in limited amounts but cannot synthesize the compound in sufficient quantities, and it must be obtained through the diet. Term "vitamin" is conditional upon the circumstances and the particular organism. For example, ascorbic acid (one form of vitamin C) is a vitamin for humans, but not for most other animal organisms. Supplementation is important for the treatment of certain health problems, but there is little evidence of nutritional benefit when used by healthy people.
13 Vitamins are universally recognized at present: A, B1, B2, B3, B5, B6, B7, B9, B12, C, D, E, K.
Vitamins are classified by their biological and chemical activity, not their structure. Vitamers by definition are convertible to the active form of the vitamin in the body.
Anti-vitamins are chemical compounds that inhibit the absorption or actions of vitamins. For example, avidin is a protein in egg whites that inhibits the absorption of biotin.
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If a tree falls in the forest and no one is there to hear it, does it make a sound?
Food energy is chemical energy that animals derive from their food and molecular oxygen through the process of cellular respiration. Humans and other animals need a minimum intake of food energy to sustain their metabolism and to drive their muscles.
Organisms derive food energy from carbohydrates, fats and proteins as well as from organic acids, polyols, and ethanol present in the diet. Some diet components that provide little or no food energy, such as water, minerals, vitamins, cholesterol, and fiber, may still be necessary to health and survival for other reasons.
Using the International System of Units, researchers measure energy in joules (J) or in its multiples; the kilojoule (kJ) is most often used for food-related quantities. An older metric system unit of energy, still widely used in food-related contexts, is the "food calorie" or kilocalorie (kcal or Cal), equal to 4.184 kilojoules.
<>Fats and ethanol have the greatest amount of food energy per mass, 37 and 29 kJ/g (8.8 and 6.9 kcal/g), respectively. Proteins and most carbohydrates have about 17 kJ/g (4.1 kcal/g).
Conventional food energy is based on heats of combustion in a bomb calorimeter and corrections that take into consideration the efficiency of digestion and absorption and the production of urine.