How to Maximize Calcium Intake
By Carolyn Richardson
Calcium is the most abundant mineral in the human body. While 1% of the body’s calcium supports critical metabolic functions like muscle function, nerve transmission and the secretion of hormones and enzymes, the other 99% is stored in the bones and teeth.
While many of us try to eat more high-calcium foods and take calcium supplements, the fact is that only 30% of the calcium we consume is absorbed into the body. There are a number of factors that affect just how well your body uses calcium and knowing these interactions will help you to benefit from your calcium intake.
Foods that Reduce Absorption
Dietary calcium from eating dairy products and taking supplements may meet the recommended daily allowances set forth by the Institute of Medicine of the National Academies, however there are factors that negatively affect how the approximate 1000 to 1300 mg a day needed for most adults stays in the body. For example, phytic acid and oxalic acid can bind to calcium and be excreted through the intestinal tract. Phytic acid is found in whole grains, nuts, and legumes, while oxalic acid is found in healthy staples such as spinach, celery, pecans, tea and beets. Another set of healthy foods that may negatively affect calcium absorption are those high in fiber and protein. And according to the Massachusetts Institute of Technology(MIT), “Alcohol, phosphates(found in soft drinks and meats), sugar, and… high levels of sodium may also be linked to calcium excretion.”
Enhancing Calcium Absorption
In addition to dairy products such as cheese, milk, and yogurt, good food sources of calcium are kelp, carob flour, kale, chinese cabbage, broccoli, rhubarb, watercress, parsley, blackcurrants, and globe artichoke. Many cereals and fruit juices are fortified with calcium, which you may also notice is fortified with Vitamin D, with good reason. Vitamin D increases the absorption of Calcium from the gastrointestinal tract. You may also find many calcium supplements also have Vitamin D, this will help the body absorb more calcium than it would had Vitamin D not been present. Another way to enhance calcium absorption is by taking supplements throughout the day. Not only is calcium absorption highest in doses less than 500 mg, but according to Washington University researchers, calcium taken at bedtime could help stave off bone loss that occurs at night.
Interactions to Avoid
Calcium interacts with many over-the-counter drugs and minerals, so take heed to the following when eating or taking calcium supplements. If you take any prescription or over-the-counter medicines regularly, ask your doctor if it's safe to use calcium supplements. Calcium can interact with drugs for heart disease, diabetes, epilepsy, and other conditions. Also, avoid taking a calcium supplement with an iron-containing foods or supplements. You may find that many multivitamins that include a high dosage of iron, have smaller amounts of calcium. The reason is because calcium inhibits iron absorption, so be sure to wait two hours between taking a calcium supplement and iron supplement. Some specific drug interactions that impact utilization of calcium include anti-inflammatory drugs known as corticosteroids. Used to treat asthma, and rheumatoid arthritis, these drugs reduce the body’s ability to activate vitamin D, and thus decrease calcium absorption. Antibiotics also seem to decrease calcium absorption. Lastly, watch out for aluminum. According to MIT, “aluminum (foods cooked in aluminum cookware including the use of acidic foods with the cookware), aluminum foil, [and] antacids containing aluminum…” inhibit calcium absorption.
Because calcium is so important to bone health and avoiding osteoporosis late in life, it’s important to consider taking calcium supplements if your diet is not adequate. According to the Office of Dietary Supplements of the National Institutes of Health, the Tolerable Upper Limit (UL) for calcium for children and adults ages 1 year and older is 2,500 mg/day. Yet, even at normal levels, calcium supplements may cause gas, bloating and constipation. When looking for calcium supplements, keep in mind that calcium carbonate is the most cost-effective source of calcium. Consider also that calcium dissolution varies from 33% to 75%, that is to say, some supplements may break down more readily in the intestinal tract than others. Lastly, watch for the elemental calcium per tablet not per serving. Sometimes labels can be confusing. Remember to track your calcium intake by checking your nutritional analysis daily after logging your food and supplements. By comparing your calcium intake daily over a week’s period, you should be able to determine if you are getting enough or may need to increase your intake of calcium.
For more information, visit the Calcium Dietary Supplement Fact Sheet.
How do you get your daily dose of calcium?
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