Calcium Importance in foods, Daily life and dietary guidelines.. know more.
Calcium, the most abundant mineral in the body, is found in some foods, is added to others, is available as a dietary
supplement, and is present in some medications such as antacids. Less than 1% of total body calcium supports critical metabolic functions required for vascular contraction and vasodilation, muscle function, nerve transmission, intracellular signaling and hormonal secretion. The remaining 99% of the body’s calcium supply is stored in the bones and teeth where it supports their structure and function.
Serum calcium is very tightly regulated and does not fluctuate with changes in dietary intakes; the body uses bone tissue as a reservoir for and source of calcium, in order to maintain constant concentrations of calcium in blood, muscle, and intercellular fluid
CALCIUM IN FOODS :
There are many dietary sources of calcium, but low-fat milk or yogurt or fortified substitutes are the most efficient and readily available. The lactose in mammalian milks appears to improve the absorption of calcium from milk. Lactose-free milk and soy, nut, rice and other grain milks fortified with calcium and vitamin D are now available. They are usually fortified to 300 mg calcium per cup, equivalent to the amount of calcium in cow’s or goat’s milk, but the nutrition label should be checked. In addition to milk, a variety of foods and calcium-fortified juices contain calcium and can help children, teens, and adults get sufficient levels of calcium in their diets. If it is difficult to get the recommended amounts of calcium from foods alone, a combination of food sources and supplements may be needed.
The absorption of calcium from the gut is increased when there is high body need such as during pregnancy and lactation, growth in infancy, childhood and adolescence, and when there is adequate vitamin D. Absorption is decreased by the presence of phytic acid and oxalic acid containing foods in the gut, alcohol and caffeine.
Calcium carbonate is the most common and least expensive calcium supplement. It can be difficult to digest and causes gas and constipation in some people. Calcium carbonate is 40% elemental calcium; 1000 mg will provide 400 mg of calcium. This supplement should be taken with food to aid in absorption. Taking magnesium with it can help to prevent constipation. Calcium citrate is more easily absorbed (bioavailability is 2.5 times higher than calcium carbonate), easier to digest, and less likely to cause constipation and gas than calcium carbonate. It also has a lower risk of contributing to the formation of kidney stones. However, it is less concentrated, providing approximately 21% elemental calcium; 1000 mg will provide 210 mg of calcium. It is more expensive than calcium carbonate, and more of it must be taken to get the amount of calcium, but it is better absorbed. It can be taken with or without food.
Calcium phosphate costs more than calcium carbonate but less than calcium citrate. It is easily absorbed and is less likely to cause constipation and gas. Calcium lactate and calcium aspartate are both more easily digested but more expensive than calcium carbonate. As the dose of calcium supplement increases, the percentage absorbed decreases. Because it appears that absorption is highest with dosages of ,500 mg at a time, it is best to take calcium supplements in at least two dosages per day.
Recommended Diet for calcium :
- Recommended Dietary Allowance (RDA): average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy individuals.
- Adequate Intake (AI): established when evidence is insufficient to develop an RDA; intake at this level is assumed to ensure nutritional adequacy.
- Estimated Average Requirement (EAR): average daily level of intake estimated to meet the requirements of 50% of healthy individuals. It is usually used to assess the adequacy of nutrient intakes in population groups but not individuals.
- Tolerable Upper Intake Level (UL): maximum daily intake unlikely to cause adverse health effects.
An Article by a nutrition student ‘Syeda Ruhina Raushan’