One of the main fat-soluble substances, vitamin D is a nutrient that will help the body absorb calcium which is needed for the maintenance of strong bones and teeth as well as nerve transmission.

Since vitamin D is a fat-soluble nutrient, it is not essential that you take it in through your diet every single day. As long as you are making sure you get some on a regular basis, the body will store it in the body fat cells and therefore if you go a day or two where you don't meet your needs, the body can call upon these reserves.

Along with helping the calcium be absorbed into the body, vitamin D also helps to maintain the right amount of calcium and phosphorus in the blood, thus playing a critical role in the prevention of osteoporosis.

You can most commonly find this nutrient in food sources like cheese, butter, cream, fortified milk, fish, oysters, cereals and margarine. You can also produce this nutrient when you are outside getting sunlight so for some individuals this may be an effective way to meet their needs.

You do need to watch out however because since this nutrient is stored by the body it can be toxic over time. Toxicity would lead to the intestines absorbing too much calcium, which can then lead to deposits being placed in the soft tissues of the heart and lungs. This reduces their ability to function making it vital you monitor your intake to ensure proper health.

If you are reaching toxic levels, some of the side effects that are often seen are vomiting, kidneys stones as well as feelings of muscle weakness.