Calcium is the most abundant mineral in the body, primarily found in bones and teeth. In bone formation, calcium forms crystals that provide strength to maturing bone. It is needed for more than just healthy bones. It is also important for muscle contraction, blood vessel contraction and expansion, the secretion of hormones and enzymes, and sending messages through the nervous system. Studies have proven its impact on heart health as a result of increased calcium intake. In addition, scientific evidence suggests that increased intake of calcium may help to maintain optimal weight as well. Calcium is often inadequately supplied, inefficiently absorbed, or excreted faster than it is being assimilated. The citrate salt of calcium has been documented to be well absorbed and utilised by the body. This is the form recommended by many doctors and nutritionists. Calcium citrate dissolves easily even if stomach acid is low. Many people naturally produce less acid as they age, so calcium citrate is a good choice for older adults. The addition of vitamin D3 is also critically important, because it stimulates calcium absorption and promotes healthy bone density. However, as people age, they often lose the ability to make vitamin D3. It is recommended to not take calcium and other minerals with fibre, because fibre can interfere with their absorption. There is evidence that calcium from supplements and dairy foods may inhibit iron absorption. However, it has been very difficult to distinguish between the effects of calcium on iron absorption and other inhibitory factors, such as phytate. Although current understanding of this suggests that the inhibition of calcium on absorption of iron is of short duration and the body has adaptive mechanisms. Calcium supplements are best taken during meals. They should always be taken with a full glass of water, juice or other liquid to enhance solubility. If calcium-containing formulas are taken only once per day, they may be best taken in the evening.