Calcium: An Essential Micronutrient
Calcium is one of the most important and essential minerals that the human body requires for good general health. Not only is it essential for the health of teeth and bones, but it is also crucial for muscle contractions (including the heart muscle), and the function of both the vascular and nervous systems. Hundreds of enzyme reactions and protein interactions require calcium as a co-factor, and the process of communication between cells also requires calcium.
The body maintains a large supply of stored calcium in bones and teeth—the majority of bone is in fact made up of calcium. Despite the existence of such a large supply of calcium in the body, dietary and supplemental calcium is still very important. This is because calcium stored in the bones is used to supply the body’s day-to-day calcium needs when there is no dietary calcium available. This mechanism is what contributes heavily to osteoporosis, as when there is too little dietary calcium on a long-term basis, calcium is continually drawn from bones, making them weak and brittle.
Dietary and supplemental calcium is therefore essential for body and bone health; however supplemental calcium in particular can actually cause health problems in people with thyroid disease.
The Thyroid Gland
The thyroid is a tiny butterfly-shaped gland located at the base of the neck. It makes a large number of different homes that help control many of the body’s processes. In particular, hormones secreted by the thyroid control the speed of the body’s metabolism.
In addition, the thyroid makes and secretes a hormone which is partially responsible for controlling blood calcium levels. This hormone is called calcitonin. It works in conjunction with another hormone called parathyroid hormone, which is produced by the parathyroid glands.
Diseases of the Thyroid
The two main types of thyroid disease are called hyperthyroidism (or overactive thyroid) and hypothyroidism (or underactive thyroid). In these diseases, some underlying factor causes the thyroid gland to produce too little or too much of its metabolism-regulating hormones.
Hyperthyroidism can cause unexplained weight loss, feelings of nervousness and anxiety, and restlessness.
Hypothyroidism can cause weight gain, depression, and feelings of lethargy.
Both conditions can cause a range of other symptoms, including hair loss, dry skin, hoarseness, and temperature intolerance.
Calcium and Thyroid Interactions
Sometimes, treatment for hyperthyroid disease requires that the thyroid gland be removed. If this happens, calcitonin will no longer be produced in the body. Because calcitonin is responsible for reducing blood calcium levels when they are too high, thyroid gland removal can result in chronically high blood calcium levels, a condition which requires treatment.
In some cases, however, the opposite can happen. If thyroid treatment damages the parathyroid glands, these glands might produce abnormal levels of parathyroid hormone. This can result in low blood calcium levels, and might be a temporary or permanent condition.
Another issue concerns people who take calcium supplements and are being treated for hypothyroidism. People with an underactive thyroid generally take synthetic thyroid hormones to boost their metabolism and relieve disease symptoms. However, calcium supplements can interfere with the body’s absorption and use of synthetic thyroid hormones. This issue is of particular concern for women, who are more likely than men to develop hypothyroidism, and are also more likely to use calcium supplements.
A simple and effective solution for many women is to ensure that synthetic thyroid hormone is taken six to twelve hours apart from calcium supplements, so that the hormone has time to be absorbed without interference. Blood tests to monitor thyroid hormone levels should be taken at regular intervals to ensure that the synthetic hormone is working.
Cancer Research UK: Life after Thyroid Surgery
National Institute of Health Office of Dietary Supplements: Dietary Supplement Fact Sheet: Calcium
Oregon State University Linus Pauling Institute: Micronutrient Information Center: Calcium