Calcium, the most common mineral in the body, plays an essential role in blood clotting, muscle contraction, nerve impulse transmission, and bone and tooth formation.
Studies indicate that calcium plays a role in blood vessel contraction and dilation which affects blood pressure.
A constant level of calcium is maintained in body fluid and tissues so that these vital body processes function efficiently. More than 99 percent of body calcium is stored in the bones and teeth; the remaining 1 percent is found in blood, muscle, and the fluid between cells.
Calcium is lost from the body every day in urine and feces, and trace amounts are lost in sweat, shedding skin, hair, and nails. The lost calcium is normally replaced by calcium from food. If your diet does not contain enough calcium or if you don’t absorb enough calcium from your food or supplements to replace the lost calcium, the body breaks down bone to get the calcium it needs.
To absorb enough calcium, your body also needs vitamin D. Your skin can make vitamin D when it is exposed to direct sunlight. Other sources of vitamin D are fatty fish, eggs, liver, butter, fortified foods such as milk and multivitamins. People at risk for having too little vitamin D are elderly adults, those in institutions and some people with chronic neurological or gastrointestinal diseases. People living in northern latitudes may need supplements in the winter to maintain adequate vitamin D levels.
According to the Office of Dietary Supplements of the National Institutes of Health, the amount of calcium you need each day depends on your age:
Children ages 1 to 3 years need 700 milligrams (mg) a day.
Children 4 to 8 years old need 1,000 mg a day.
Children 9 to 18 need 1,300 mg a day.
Adults ages 19 to 50 should get 1,000 mg a day.
Ages 50 to 70: Men should get 1,000 mg a day; women should get 1,200 mg a day.
Both men and women older than 70 should get 1,200 mg a day.
The best way to get calcium is from food. The U.S. Department of Agriculture recommends a minimum of three cups of nonfat or low-fat vitamin D-fortified milk or equivalent milk products each day.
A consistent level of calcium in the body’s fluids and tissues is needed for muscle contraction, blood vessel contraction and expansion, the secretion of hormones and enzymes, and transmission of messages through the nervous system. Adequate calcium and vitamin D intake throughout a person’s lifetime can help build and maintain proper bone mass, helping to prevent osteoporosis.
Calcium from dairy products in combination with a diet high in fruits, vegetables, and low-fat dairy can help keep blood pressure in check and help prevent the absorption of dietary fat; this helps decrease blood cholesterol.
Calcium may need a boost from other nutrients to help achieve these health benefits. In most studies that looked at calcium and prevention of disease, milk was the major source of calcium. In addition to calcium, milk contains potassium, magnesium, vitamin D, and vitamin A. The extent to which these other components work with calcium to prevent conditions is not known.
Getting enough calcium
To ensure you consume enough calcium each day, start with food and drink. Calcium in food is better absorbed by the body than calcium in a supplement. The additional compounds in dairy products act with calcium to promote its benefits. Strive to consume at least three calcium-rich foods daily such as low-fat or nonfat yogurt, 1 percent or skim milk, low-fat ice cream, calcium-fortified orange or grapefruit juice, low-fat cheese and low-fat cottage cheese.
Also, look for foods with added calcium such as rice and some breakfast cereals.
If you're lactose intolerant, don't avoid dairy products. Lactose intolerance is easy to manage.
Aged cheese and yogurt tend to be more easily digested by people who are lactose intolerant; eat them in small quantities along with other food. Foods made with active or "live" cultures, like yogurt or buttermilk, are also easier to digest because their "friendly" bacteria help digest lactose. Other options include lactose-free milk, lactose-free cottage cheese and nondairy sources of calcium, such as calcium-fortified soy milk, tofu, baked beans, almonds, broccoli, kale and other dark green leafy vegetables, and canned salmon and sardines with the bones. For canned fish, you need to eat the bones to get the calcium.
Vitamin D is necessary for your body to absorb the calcium you get from foods or supplements. You can get vitamin D from foods fortified with it or by spending five to 30 minutes in the sun between 10 a.m. and 3 p.m. at least two times per week. Adults 19 to 50 need at least 600 international units (IU) of vitamin D a day; those 51 and older need 800 IU a day.
Sizing up your supplement
Although lots of foods contain calcium, for the most part, people are still not meeting the recommended intake.
If you're not consuming at least three calcium-rich foods per day, consider taking a calcium supplement. If you use a supplement, however, don't depend on it to meet your calcium needs.
A good bet: Take a 500 mg calcium supplement each day and try to get the remaining 500 to 700 mg of calcium from food. In order to absorb the most calcium, you should take only 500 mg or less at one time.
Calcium supplements come in different forms, such as calcium carbonate and calcium citrate. Some have vitamin D added to them for extra benefit. Calcium carbonate is affordable and is also found in some antacid tablets. Because it relies on stomach acid for absorption, it is absorbed best when taken with food. Calcium citrate is absorbed the same with or without food and is good for people with low stomach acid.
Research indicates that calcium citrate is absorbed better than other supplements, such as calcium carbonate. But to enhance a calcium supplement's absorption, take it with a citrus-based food, such as orange juice.
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