The absorption process usually begins three to six hours after eating. In general, carbohydrates are digested faster, followed by protein absorption and then fat. The exact time of digestion depends on the food you have eaten, the complexity of the molecule, the nature of the nutrient and the order of decay that occurs in the digestive system. The body develops a vitamin deficiency if it doesn't have enough of one or more vitamins for daily bodily functions or specific needs.
Water-soluble vitamins are absorbed more quickly than fat-soluble vitamins, so water-soluble vitamins work faster than fat-soluble vitamins. The amount of time it takes to digest food and absorb nutrients varies from person to person, especially when it comes to transit times through different sections of the gastrointestinal tract. In that case, your body will absorb and use that vitamin D almost immediately (as soon as vitamin D is available through digestion). Each nutrient is absorbed differently, so if you take supplements gradually, you'll confuse your body.
Between the two options, vitamins injected intravenously are much more bioavailable (more on that later) and are more rapidly absorbed by the body. In addition, it takes longer for the body to absorb nutrients through the intestines than it does to absorb them directly from the bloodstream. This feature allows water-soluble vitamins to be quickly and easily absorbed into body tissues. The bioavailability of a vitamin or other compound is best understood as the amount of that vitamin content that the body can absorb or use.
A vitamin deficiency can cause the body to absorb certain vitamins more quickly when it senses that they are entering the body. Although you eat and excrete every day, the digestive process and the way your body absorbs nutrients are more complicated than you might think. The digestive system moves food through the gastrointestinal tract and breaks it down into smaller parts that the body absorbs in the form of macronutrients, vitamins, and minerals. Fat-soluble vitamins, such as vitamins A, D, E and K, are easily absorbed through the intestinal tract with the help of fat molecules and are stored in the liver and adipose tissue for use by the body.