B vitamins

[1] B vitamins are present in protein-rich foods, such as fish, poultry, meat, dairy products, and eggs; they are also found in leafy green vegetables, beans, and peas.

For this reason, it is common in many countries (including the United States) that the B vitamins thiamine, riboflavin, niacin, and folic acid are added back to white flour after processing.

[3] Sources for B vitamins also include spinach, legumes (pulses or beans), whole grains, asparagus, potatoes, bananas, chili peppers, breakfast cereals.

[7] Because they are soluble in water, excess B vitamins are generally readily excreted, although individual absorption, use and metabolism may vary.

[10] To the right, a diagram of some of the major B vitamins (2, 3, 5, 9, and 12) are shown as precursors for certain essential biochemical reactants (FAD, NAD+, coenzyme A, and heme B respectively).

The structural similarities between them are highlighted, which illustrates the precursor nature of many B vitamins while also showing the functionality of the end product used by essential reactions to support human, animal, or cellular life.

FAD, NAD+, and coenzyme A are all essential for the catabolic release of free energy (dG) to power the activity of the cell and more complex life forms.

Heme B is the porphyrin derivative macrocycle molecule that holds the iron atom in place in hemoglobin, allowing for the transportation of oxygen through blood.