Vitamin D absorption can be maximized by ensuring that your liver and kidneys are functioning properly, getting 10-20 minutes of daily exposure to sunlight and increasing your ingestion of good sources of the vitamin. You can also maximize vitamin D absorption by eating a full, balanced meal when taking supplements and by ensuring that natural fat is present in your diet. Not all of these measures can be taken by everyone wishing to increase absorption of this vitamin. Consideration must be given to your individual case.
The liver and kidneys are where vitamin D synthesis takes place from pre-vitamins D2 and D3, sometimes referred to as calciferol. If your liver and kidneys are not fully functioning, vitamin D absorption will almost always be decreased. It is, therefore, usually a good idea to attend to any problems with your liver and kidneys if you want to or need to maximize synthesis of vitamin D, also known as calcitrol, which in turn maximizes absorption of the nutrient. Sometimes this is accomplished simply by performing an all-natural, effective cleanse of these organs.
Exposure to sunlight not only is a source of the vitamin, it can be considered a way to naturally maximize vitamin D absorption, because if you increase your intake of the vitamin, you generally also will increase absorption of it. There are a few things to keep in mind with this measure as well as a precaution. People who have a skin disease or skin cancer usually should not attempt to increase vitamin D absorption in this way because of the detrimental effect sunlight could have on their skin. Remember that clothing and the use of sunblock can partially or completely hinder your results, so at least some portion of skin to which sunblock has not been applied should be exposed to sunlight.
Eating foods that are rich in vitamin D is probably the most obvious way to increase absorption — the more of the nutrient in the diet, the more that will be absorbed. Good sources include tuna, salmon, cod liver oil, sardines, whole eggs and fat-reduced milk or whole milk. Many people, particularly those who are overweight, choose fat-reduced and fat-free foods, but vitamin D absorption cannot be maximized without the presence of sufficient fat. This is why, when taking a supplement, it is advisable to take it with a full meal that contains some natural fat.