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Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium ...
There are 20 trace elements and minerals that are essential in small quantities to body function and overall human health. [ 114 ] Iron deficiency is the most common inadequate nutrient worldwide, affecting approximately 2 billion people. [ 115 ]
Most biomolecules are organic compounds, and just four elements—oxygen, carbon, hydrogen, and nitrogen—make up 96% of the human body's mass. But many other elements, such as the various biometals, are also present in small amounts.
Just six elements—carbon, hydrogen, nitrogen, oxygen, calcium and phosphorus—make up almost 99% of the mass of living cells, including those in the human body (see composition of the human body for a complete list). In addition to the six major elements that compose most of the human body, humans require smaller amounts of possibly 18 more.
The human body is composed of elements including hydrogen, oxygen, carbon, calcium and phosphorus. These elements reside in trillions of cells and non-cellular components of the body. The adult male body is about 60% total body water content of some 42 litres (9.2 imp gal; 11 US gal).
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 .
The idea of chemical principles developed out of the classical elements. Paracelsus identified the tria prima as principles in his approach to medicine . In his book The Sceptical Chymist of 1661, Robert Boyle criticized the traditional understanding of the composition of materials and initiated the modern understanding of chemical elements .
All macronutrients except water are required by the body for energy, however, this is not their sole physiological function. The energy provided by macronutrients in food is measured in kilocalories, usually called Calories, where 1 Calorie is the amount of energy required to raise 1 kilogram of water by 1 degree Celsius. [27]