Fundamentos de Nutrição
Vitamins Vitamins do not supply the body with energy in the form of calories- a fact that distinguishes them from fat, carbohydrate, and protein. However, many vitaminsregulate the chemical reactions that allow us to obtain energy from those nutrients. Vitamins differ from fat, protein, and carbohydrate in other important ways. For one, the amounts of vitamins a bodyneeds daily-a mere microgram or in some cases-are infinitesimal compared to the grams of fat, carbohydrate, and protein required each day. Another difference is structural: vitamins are individual unitsrather than long chains of smaller units. Like fat, carbohydrate, and proteins, however, vitamins are organic (carbon-containing) compounds essential for normal functioning, growth, and maintenance ofthe body. Aula 5

Fundamentos de Nutrição
Vitamins Vitamins A, D, E, and K are lipid-like molecules that are soluble in fat. The B vitamins and Vitamin C, on the other hand, are soluble in water.This difference in solubility affects the way the body absorbs, transports, and stores vitamins .

Aula 5

Fundamentos de Nutrição
Vitamins Intestinal cells absorb fat-soluble vitamins alongwith dietary fat. The amount absorbed typically varies from 40 to 90 percent of the amount consumed; efficiency of absorption generally falls as the dietary intake rises above the body's needs. Justlike triglycerides and other dietary lipids, lipoproteins carry absorbed fat-soluble vitamins on their journey through the lymph and bloodstream. As chylomicrons move through the blood, cells take upmost of the triglycerides and leave behind chylomicron remnants that contain the fat-soluble vitamins. The liver picks up these remnants and either stores the vitamins for future use or repackages themfor delivery via the bloodstream to other tissues.

Aula 5

Fundamentos de Nutrição
Vitamins Water-soluble vitamins are dissolved in the watery compartments of foods. Once absorbed, these... [continua]

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