A calcium-enriched diet involves adding more of this mineral as a percentage of the dietary whole. The additional calcium is naturally supplied within foods or added to the foods during processing. Calcium cannot be created by the body; it has to be provided through the diet.
Calcium Function
The skeleton contains 99 percent of the body's calcium. The rest is within blood plasma or fluids surrounding body cells. Hormones--parathyroid and calcitonin--regulate blood calcium levels, and vitamin D is required for proper calcium absorption. Most calcium functions to build bones and teeth, but the remainder is extremely important in blood clotting, nerve conduction, muscle contractions and enzyme regulation. Current investigations hypothesize that diets meeting calcium requirements may actually lower blood pressure, and incidence of colon and rectal cancers.
Dietary Calcium
The best source of calcium is from food. The largest source of dietary calcium is in dairy products such as milk, yogurt and cheese. Also, any small fish consumed with small bones intact, like sardines, are a good source of calcium. Most vegetables contain calcium, but in low amounts. Adolescents 9 to 18 years old require the highest amount of calcium intake at 1,300 mg per day. Adults 19 to 50 years old require 1,000 mg per day, while the elderly have an increased requirement of 1,200 mg per day. Not all consumed calcium is absorbed into the body. Absorption depends on age, vitamin D intake and types of foods consumed. High levels of oxalic acid in spinach, sweet potatoes and rhubarb actually reduce calcium absorption.
Fortified Foods
Calcium-fortified foods contain added calcium. Either the food does not normally contain calcium, or it has been removed during processing and added back later. Many fruit juices come calcium-fortified, as do some cereals, breads, bottled water and frozen waffles. These can be additional sources to increase dietary calcium uptake, especially during years of bone growth. With 90 percent of adult bone mass established during the teenage years, full amounts of calcium consumption need to be obtained.
Supplements
Calcium supplements contain variable amounts of elemental calcium. Calcium citrate may only contain 21 percent calcium, whereas calcium carbonate is 40 percent. These percentages need to be taken into account when total calcium intake is calculated. Also, these supplements should only be taken if dietary calcium intake is consistently low. Some vegetarian diets are consistently low in minerals. Occasionally, calcium supplements cause excess gas, bloating, constipation and upset stomach. Do not take more calcium than required. The excess calcium will be excreted by the kidneys, causing them to work extra hard during the elimination process.
Children and Elderly
As children and the elderly require higher amounts of dietary calcium, calcium-enriched diets are an integral part of adequate calcium levels in these individuals. In addition, if nursing mothers do not consume enough calcium and vitamin D, infants become calcium deficient. Deficiency requires the body system to remove the needed calcium from its bones. This results in deformed bone growth, short stature and high fracture incidence in the youngest. Low levels in the elderly lead to osteoporosis, or porous and fragile bones--especially in women with decreased estrogen levels.
Lactose Intolerance
People with lactose intolerance may need special dietary planning to provide an adequate calcium-enriched diet. Since the highest amounts of calcium are present in dairy products, alternative calcium-enriched foods need to be increased. Cheeses and yogurts may be better tolerated than milk. Vegetables rich in calcium include turnip greens, kale and Chinese cabbage. Non-lactose, low-lactose and soy milk beverages contain added calcium, which can supplement foods. Luckily, calcium-fortified foods are increasing in availability, making diet planning easier for these individuals.
References
- National Institutes of Health, Office of Dietary Supplements: Calcium
- State of Missouri, Department of Health and Senior Services: Calcium
- National Osteoporosis Foundation: Calcium, What You Should Know
- "Pediatrics"; Calcium Requirements of Infants, Children, and Adolescents; Committee on Nutrition; 1999
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