Vitamin B12, also called cobalamin, is a water-soluble vitamin that has a key role in the normal functioning of the brain and nervous system, and the formation of red blood cells. It is involved in the metabolism of every cell of the human body, especially affecting DNA synthesis, fatty acid and amino acid metabolism.
No fungi, plants, nor animals (including humans) are capable of producing vitamin B12. Only bacteria and archaea have the enzymes needed for its synthesis. Proved food sources of B12 are animal products (meat, fish, dairy products). Some research states that certain non-animal products possibly can be a natural source of B12 because of bacterial symbiosis.
B12 is the largest and most structurally complicated vitamin and can be produced industrially only through a bacterial fermentation-synthesis. This synthetic B12 is used to fortify foods and sold as a dietary supplement.
Vitamin B12 consists of a class of chemically related compounds (vitamers), all of which show pharmacological activity. It contains the biochemically rare element cobalt (chemical symbol Co). The vitamer is produced by bacteria as hydroxocobalamin, but conversion between different forms of the vitamin occurs in the body after consumption.
B12 aids in lowering homocysteine levels and may lower the risk of heart disease.
Recommended daily amount: 2.4 mcg.
Example sources: fortified cereals, doenjang and chunggukjang (fermented soybeans), nori (seaweed).
Water is an essential nutrient - it is required in amounts that exceed the body's ability to produce it. All biochemical reactions occur in water. It fills the spaces in and between cells and helps form structures of large molecules such as protein and glycogen.
Most foods contain water. The body can usually get 20% of its total water requirements from solid foods alone. The human body can last weeks without food, but only days without water.
The digestion process also produces water as a byproduct and can provide around 10 per cent of the body’s water requirements.
Water is a transparent and nearly colorless chemical substance. Its chemical formula is H2O, meaning that its molecule contains one oxygen and two hydrogen atoms.
Water covers 71% of the Earth's surface. It is vital for all known forms of life. On Earth, 97% of the planet's crust water is found in seas and oceans, 1.7% in groundwater, 1.7% in glaciers and the ice caps. Only 2.5% of this water is freshwater, and 98.8% of that water is in ice (excepting ice in clouds) and groundwater. Less than 0.3% of all freshwater is in rivers, lakes.
Safe drinking water is essential to humans and other lifeforms even though it provides no calories or organic nutrients. ~One billion people still lack access to safe water. It was estimated that by 2025 more than half of the world population will be facing water-based vulnerability, and by 2030 water demand in some developing regions of the world will exceed supply by 50%.
Approximately 70% of the freshwater used by humans goes to agriculture.