1. What is calcium?

Calcium is an essential dietary mineral commonly found in milk, yogurt, cheese, and dark green vegetables. It also is found in certain grains, legumes (including peas, beans, lentils, and peanuts), and nuts.

Calcium is a major component of bones and teeth. It also is required for the clotting of blood to stop bleeding and for normal functioning of the nerves, muscles, and heart.

2. How much calcium is needed for good health?

Calcium is an important part of a healthy diet; however, the recommended intake differs according to age. As can be seen in the following table, the highest recommended intake is for children and adolescents between the ages of 9 and 18, when bones are growing rapidly.

Dietary Recommendations for Calcium, Males and Females*

Age Group	Dietary Recommendations (mg**/day)
0-6 months	210 mg
7-12 months	270 mg
1-3 years	500 mg
4-8 years	800 mg
9-18 years	1300 mg
19-50 years	1000 mg
51 years and older	1200 mg

*1997 National Academy of Sciences Panel on Calcium

and Related Nutrients (1).

**mg = milligram.

For adults (including women who are pregnant or breastfeeding) and for children age 1 or older, the safe upper limit of calcium intake is 2.5 grams (or 2500 mg) per day (1).

Too much calcium in the diet and from dietary supplements can lead to unwanted side effects (see Question 4 for information about side effects).

The U.S. Department of Agriculture’s 1994–1996 Continuing Survey of Food Intakes by Individuals showed that the average daily calcium intakes in the United States for males and females over age 9 were 925 mg and 657 mg, respectively, or less than the recommended intake (2).


3. How much calcium is in foods and calcium supplements?

Calcium is found in many foods. Foods high in calcium include dairy products, dark green vegetables, some soy products, fish, nuts, and legumes. The following table shows how much calcium is contained in some common foods.

Calcium Amounts in Some Common Foods*

Food, Standard Amount	Calcium (mg)
Fruit yogurt, low-fat yogurt, 8 oz**	345
Mozzarella cheese, part-skim, 1.5 oz	311
Fat-free (skim) milk, 1 cup	306
Sardines, Atlantic, in oil, drained, 3 oz	325
Tofu, firm, prepared with nigari, ½ cup	253
Spinach, cooked from frozen, ½ cup	146
White beans, canned, ½ cup	96

*Note: This list is not intended to be exhaustive. Adapted from

the U.S. Department of Health and Human Services Dietary

Guidelines for Americans 2005.

**oz = ounces.

Packaged foods are required to have a Nutrition Facts label (3). On foods that contain calcium, this label lists how much calcium there is in each serving of the packaged food. However, the Nutrition Facts labels on packaged foods do not list the calcium content in mg. They only provide the Percent Daily Value (%DV), which is the amount one serving of a food item contributes to the total amount of calcium you need each day. The %DV for calcium is based on a recommended Daily Value of 1000 mg per day. Therefore, a food with 20%DV or more contributes a fair amount of a person’s daily total, whereas a food with 5%DV or less contributes only a little. As an example, 1 cup of milk provides 300 mg of calcium and 30%DV.

Calcium supplements most often contain either calcium carbonate or calcium citrate, which are calcium salts. Sometimes, they contain both compounds. Calcium carbonate and calcium citrate have different amounts of elemental calcium, which is the actual amount of usable calcium in a supplement. Specifically, calcium carbonate has about 40 percent elemental calcium, meaning that 500 mg of calcium carbonate actually contains 200 mg of elemental calcium or 20%DV. In contrast, calcium citrate has approximately 21 percent elemental calcium. Therefore, nearly twice as much calcium citrate is needed to obtain the equivalent amount of elemental calcium as in calcium carbonate. Calcium supplements may also contain other calcium salts, but the body may not be able to use the calcium in these compounds. As with food labels, you should look at the Nutrition Facts label on a supplement to determine how much calcium it contains.


4. Is it safe to take calcium supplements?

For most people, it is safe to eat foods containing calcium and to take calcium supplements that together do not exceed the tolerable upper intake level of 2.5 grams of calcium per day. This upper level for daily calcium intake in adults is the highest level that likely will not pose risks of unwanted side effects in the general population. The upper level of 2.5 grams a day is an average recommendation for all healthy people who are older than a year, regardless of gender.

Consuming too much calcium—in excess of 5 grams a day, or 3 grams a day in people with existing kidney problems (4)—can lead to several harmful side effects. Most of these side effects result from people taking too many calcium supplements. Rare harmful side effects from excess calcium include kidney stones (5), hypercalcemia (too much calcium in the blood), and kidney failure (1). In addition, excessive consumption of milk (which is high in calcium) and some types of antacids, especially antacids containing calcium carbonate or sodium bicarbonate (baking soda), over a long period of time can cause milk-alkali syndrome, a condition that can also lead to calcium deposits in the kidneys and other tissues and to kidney failure (4, 6, 7).


5. Is there evidence that calcium may help reduce the risk of colorectal cancer?

The results of epidemiologic studies regarding the relationship between calcium intake and colorectal cancer risk have not always been consistent.

In the American Cancer Society’s Cancer Prevention Study II Nutrition Cohort, the diet, medical history, and lifestyle of more than 120,000 men and women were analyzed (8). Men and women who had the highest intakes of calcium through both their diet and supplement use had a modestly reduced risk of colorectal cancer compared with those who had the lowest calcium intakes. However, the benefit from calcium appeared to plateau, or level off, at an intake of approximately 1200 mg per day. When calcium from the diet was analyzed by itself, no reduction in colorectal cancer risk was found. However, the use of calcium supplements in any amount was associated with reduced risk. This association was strongest (a 31 percent reduction in risk) for people who took calcium supplements of 500 mg per day or more.

A stronger relationship between calcium intake and colorectal cancer risk was found when participants of the Nurses’ Health Study and the Health Professionals Follow-up Study were combined in an analysis that included more than 135,000 men and women (9). Individuals who had a calcium intake of more than 700 mg per day had a 35 percent to 45 percent reduced risk of cancer of the distal (lower) part of the colon than those who had a calcium intake of 500 mg or less per day. No association was found between calcium intake and risk of cancer of the proximal (middle and upper) part of the colon (9). Another large study of Finnish men showed a similar relationship between higher calcium intake and reduced risk of colorectal cancer (10). This study, however, did not evaluate proximal and distal colorectal cancers separately.

In a study that included more than 61,000 Swedish women, colorectal cancer risk was approximately 28 percent lower among individuals who had the highest calcium intakes (approximately 800–1000 mg per day) compared with those with the lowest calcium intakes (approximately 400–500 mg per day) (11). Data from this study also suggested that the benefit associated with calcium was limited to the distal colon (11). In a study that involved more than 34,000 postmenopausal Iowa women, high intakes of calcium (approximately 1280 mg per day or more) compared with lower calcium intakes (approximately 800 mg per day or less) from both the diet and supplements were associated with a 41 percent reduction in risk of rectal cancer (12). Reduced risks of rectal cancer were also observed for dietary calcium alone and supplemental calcium alone, but these associations were not statistically significant (12).

In an analysis involving more than 293,000 men and 198,000 women in the National Institutes of Health-American Association of Retired Persons (NIH-AARP) Diet and Health Study, high intakes of total calcium, dietary calcium, and supplemental calcium were associated with an approximately 20 percent lower risk of colorectal cancer among men and an approximately 30 percent lower risk of colorectal cancer among women (13).

Findings from two large randomized, placebo-controlled clinical trials, the Calcium Polyp Prevention Study (14, 15) and the European Cancer Prevention Organisation Intervention Study (16) showed that daily supplementation with 1200 to 2000 mg elemental calcium was associated with a reduced risk of recurrence of colorectal polyps known as adenomas in both men and women. Adenomas are thought to be the precursors of most colorectal cancers. In these trials, individuals who previously had one or more large adenomas removed during colonoscopy were randomly assigned to receive calcium supplementation or a placebo, and the rates of polyp recurrence and other factors were compared between the groups.

The Calcium Polyp Prevention Study involved 930 participants who were randomly assigned to receive 3 grams of calcium carbonate (1200 mg elemental calcium) daily for 4 years or a placebo and then receive follow-up colonoscopies approximately 9 months later and again 3 years after that. Compared with those in the placebo group, the individuals assigned to take calcium had about a 20 percent lower risk of adenoma recurrence (14, 15).

The European Cancer Prevention Organisation Intervention Study involved
665 participants who were randomly assigned to one of three treatment groups: 2 grams of elemental calcium daily (from calcium gluconolactate and calcium carbonate), 3 grams of fiber supplementation daily, or a placebo (16). The results showed that calcium supplementation was associated with a modest reduction in the risk of adenoma recurrence, but this finding was not statistically significant.

The results of another clinical trial conducted as part of the Women’s Health Initiative showed that supplementation with 1000 mg elemental calcium (from calcium carbonate) per day for an average duration of 7 years was not associated with a reduced risk of colorectal cancer (5). The calcium supplements in this trial also contained vitamin D (400 international units [IU]). During the trial, 128 cases of invasive colorectal cancer were diagnosed in the supplementation group and 126 cases were diagnosed in the placebo group.

In 2007, the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) published the most authoritative review of existing evidence relating food, nutrition, and physical activity to cancer risk. The report concluded that calcium probably has a protective effect against colorectal cancer (17).


6. Is there evidence that calcium can help reduce the risk of other cancers?

The results of some studies suggest that a high calcium intake may decrease the risk of one or more types of cancer, whereas other studies suggest that a high calcium intake may actually increase the risk of prostate cancer.

In a randomized trial that included nearly 1200 healthy, postmenopausal Nebraska women, individuals were randomly assigned to receive daily calcium supplementation alone (300–600 mg elemental calcium), calcium supplementation (300–600 mg elemental calcium) combined with vitamin D supplementation (1000 IU), or a placebo for 4 years (18). The incidence of all cancers combined was approximately 60 percent lower for women who took the calcium plus vitamin D supplements compared with women who took the placebo. A lower risk of all cancers combined was also observed for women who took calcium supplements alone, but this finding was not statistically significant. The numbers of individual types of cancer diagnosed during this study were too low to be able to draw reliable conclusions about cancer-specific protective effects.

The results of some but not all studies suggest that a high intake of calcium may increase the risk of prostate cancer. For example, the European Prospective Investigation into Cancer and Nutrition analyzed the intakes of animal foods (meat, poultry, fish, dairy products, etc.), protein, and calcium in relation to prostate cancer risk among more than 142,000 men and found that a high intake of protein or calcium from dairy products was associated with an increased risk of prostate cancer (19). Calcium from nondairy sources, however, was not associated with increased risk (19). In addition, a prospective analysis of dairy product and calcium intakes among more than 29,000 men participating in the National Cancer Institute’s (NCI) Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial showed increased risks for prostate cancer associated with high dietary intakes of calcium and dairy products, particularly low-fat dairy products (20). Calcium from supplements was not associated with increased prostate cancer risk (20). In contrast, results from the NIH-AARP Diet and Health Study showed no increased risk of prostate cancer associated with total calcium, dietary calcium, or supplemental calcium intakes (14, 21).

Other studies have suggested that intakes of low-fat milk, lactose, and calcium from dairy products may reduce the risk of ovarian cancer, but this risk reduction has not been found in all studies (14, 22).

An analysis from the Nurses’ Health Study that included more than 3,000 women found that higher calcium intakes (more than 800 mg per day) from dairy products—particularly low-fat or nonfat milk, yogurt, and cheese—compared with lower calcium intakes (200 mg or less per day) from dairy products was associated with a reduced risk of breast cancer among premenopausal but not postmenopausal women (23). Calcium from nondairy sources was not associated with a reduction in risk (23). Another analysis that involved more than 30,000 women in the Women’s Health Study found a reduced risk of breast cancer associated with higher (1366 mg per day or more) versus lower (less than 617 mg per day) total intakes of calcium among premenopausal but not postmenopausal women (24). In this study, higher versus lower calcium intakes from the diet, from supplements, and from total dairy products were not associated with reduced risk (24).


7. How might calcium help prevent cancer?

Although the exact mechanism by which calcium may help reduce the risk of colorectal cancer is unclear, researchers know that, at the biochemical level, calcium binds to bile acids and fatty acids in the gastrointestinal tract to form insoluble complexes known as calcium soaps. This reduces the ability of the acids (or their metabolites) to damage cells in the lining of the colon and stimulate cell proliferation to repair the damage. Calcium may also act directly to reduce cell proliferation in the lining of the colon or cause proliferating colon cells to undergo differentiation, which, in turn, leads to a reduction in cell proliferation. Calcium also may improve signaling within cells and cause cancer cells to differentiate and/or die (25, 26).

8. How does the body absorb calcium from foods and supplements?

Calcium is absorbed passively (no cellular energy required) in the intestines by diffusing through the spaces between cells. It is also absorbed actively (cellular energy required) through intestinal cells by binding to a transport protein known as calbindin. The production of calbindin is dependent on vitamin D (27).

9. Does NCI recommend the use of calcium supplements to prevent colorectal cancer?

No. Although substantial evidence suggests that calcium may provide some protection against colorectal cancer, the evidence of potential benefit from calcium supplements is limited and inconsistent. Therefore, NCI does not recommend the use of calcium supplements to reduce the risk of colorectal or any other type of cancer.

Selected References

1. Calcium. In: Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. National Academy Press, Washington, DC. Retrieved February 20, 2009, from:
   http://books.nap.edu/openbook.php?record_id=5776&page=71.
2. U.S. Department of Agriculture. Results from the Continuing Survey of Food Intakes by Individuals (CSFII) and the Diet and Health Knowledge Survey (DHKS), 1994–96. Retrieved February 20, 2009, from: http://www.ars.usda.gov/Services/docs.htm?docid=7760.
3. U.S. Food and Drug Administration (2004). How to Understand and Use the Nutrition Facts Label. Retrieved February 20, 2009, from: http://www.cfsan.fda.gov/~dms/foodlab.html.
4. Caruso JB, Patel RM, Julka K, Parish DC. Health-behavior induced disease: Return of the milk-alkali syndrome. Journal of General Internal Medicine 2007; 22(7):1053–1055.

5. Wactawski-Wende J, Kotchen JM, Anderson GL, et al. Calcium plus vitamin D supplementation and the risk of colorectal cancer. New England Journal of Medicine 2006; 354(7):684–696.
6. Gordon MV, Hamblin PS, McMahon LP. Life-threatening milk-alkali syndrome resulting from antacid ingestion during pregnancy. Medical Journal of Australia 2005; 182(7):350–351.
7. Beall DP, Henslee HB, Webb HR, Scofield RH. Milk-alkali syndrome: A historical review and description of the modern version of the syndrome. American Journal of the Medical Sciences 2006; 331(5):233–242.

8. McCullough ML, Robertson AS, Rodriguez C, et al. Calcium, vitamin D, dairy products, and risk of colorectal cancer in the Cancer Prevention Study II Nutrition Cohort (United States). Cancer Causes and Control 2003; 14(1):1–12.

9. Wu K, Willett WC, Fuchs CS, Colditz GA, Giovannucci EL. Calcium intake and risk of colon cancer in women and men. Journal of the National Cancer Institute 2002; 94(6):437–446.
10. Pietinen P, Malila N, Virtanen M, et al. Diet and risk of colorectal cancer in a cohort of Finnish men. Cancer Causes and Control 1999; 10(5):387–396.
11. Terry P, Baron JA, Bergkvist L, Holmberg L, Wolk A. Dietary calcium and vitamin D intake and risk of colorectal cancer: A prospective cohort study in women. Nutrition and Cancer 2002; 43(1):39–46.
12. Zheng W, Anderson KE, Kushi LH, et al. A prospective cohort study of intake of calcium, vitamin D, and other micronutrients in relation to incidence of rectal cancer among postmenopausal women. Cancer Epidemiology, Biomarkers and Prevention 1998; 7(3):221–225.

13. Park Y, Leitzmann MF, Subar AF, Hollenbeck A, Schatzkin A. Dairy food, calcium, and risk of cancer in the NIH-AARP Diet and Health Study. Archives of Internal Medicine 2009; 169(4):391–401.
14. Baron JA, Beach M, Mandel JS, et al. Calcium supplements for the prevention of colorectal adenomas. Calcium Polyp Prevention Study Group. New England Journal of Medicine 1999; 340(2):101–107.
15. Baron JA, Beach M, Mandel JS, et al. Calcium supplements and colorectal adenomas. Polyp Prevention Study Group. Annals of the New York Academy of Sciences 1999; 889:138–145.

16. Bonithon-Kopp C, Kronborg O, Giacosa A, Räth U, Faivre J. Calcium and fibre supplementation in prevention of colorectal adenoma recurrence: A randomized intervention trial. Lancet 2000; 356(9238):1300–1306.
17. World Cancer Research Fund/American Institute for Cancer Research. Food, Nutrition, Physical Activity, and the Prevention of Cancer: A Global Perspective. 2007. American Institute for Cancer Research, Washington, DC. Retrieved February 20, 2009, from:
    http://www.dietandcancerreport.org.
18. Lappe JM, Travers-Gustafson D, Davies KM, Recker RR, Heaney RP. Vitamin D and calcium supplementation reduces cancer risk: Results of a randomized trial. American Journal of Clinical Nutrition 2007; 85(6):1586–1591.
19. Allen NE, Key TJ, Appleby PN, et al. Animal foods, protein, calcium and prostate cancer risk: The European Prospective Investigation into Cancer and Nutrition. British Journal of Cancer 2008; 98(9):1574–1581.
20. Ahn J, Albanes D, Peters U, et al. Dairy products, calcium intake, and risk of prostate cancer in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Cancer Epidemiology, Biomarkers and Prevention 2007; 16(12):2623–2630.
21. Park Y, Mitrou P, Kipnis V, et al. Calcium, dairy foods, and risk of incident and fatal prostate cancer: The NIH-AARP Diet and Health Study. American Journal of Epidemiology 2007; 166(11):1270–1279.

22. Goodman MT, Wu AH, Tung KH, et al. Association of dairy products, lactose, and calcium with the risk of ovarian cancer. American Journal of Epidemiology 2002; 156(2):148–157.
23. Shin MH, Holmes MD, Hankinson SE, et al. Intake of dairy products, calcium, and vitamin D and risk of breast cancer. Journal of the National Cancer Institute 2002; 94(17):1301–1311.
24. Lin J, Manson JE, Lee IM, et al. Intakes of calcium and vitamin D and breast cancer risk in women. Archives of Internal Medicine 2007; 167(10):1050–1059.
25. Milner JA, McDonald SS, Anderson DE, Greenwald P. Molecular targets for nutrients involved with cancer prevention. Nutrition and Cancer 2001; 41(1–2):1–16.
26. Lamprecht SA, Lipkin M. Cellular mechanisms of calcium and vitamin D in the inhibition of colorectal carcinogenesis. Annals of the New York Academy of Sciences 2001; 952:73–87.
27. Bronner F. Mechanisms of intestinal calcium absorption. Journal of Cellular Biochemistry 2003; 88(2):387–393.

# # #

• National Cancer Institute Fact Sheet, Colorectal Cancer Research from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial: NCI Fact Sheet ¹
  (http://www.cancer.gov/cancertopics/factsheet/ColorectalPLCO)
• PDQ® Prevention Summary for Health Professionals on Colorectal Cancer ²
  (http://www.cancer.gov/cancertopics/pdq/prevention/colorectal/HealthProfessional)
• Cancer Prevention Home Page ³
  (http://www.cancer.gov/cancertopics/prevention-genetics-causes/prevention)
• Colon and Rectal Cancer Home Page ⁴
  (http://www.cancer.gov/cancertopics/types/colon-and-rectal)
• Energy Balance: Weight and Obesity, Physical Activity, Diet Home Page ⁵
  (http://www.cancer.gov/cancertopics/energybalance)

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Glossary Terms

A tumor that is not cancer. It starts in gland-like cells of the epithelial tissue (thin layer of tissue that covers organs, glands, and other structures within the body).

A process in which anything complex is separated into simple or less complex parts.

A fluid made by the liver and stored in the gallbladder. Bile is excreted into the small intestine, where it helps digest fat.

A tissue with red blood cells, white blood cells, platelets, and other substances suspended in fluid called plasma. Blood takes oxygen and nutrients to the tissues, and carries away wastes.

Cancer that forms in tissues of the breast, usually the ducts (tubes that carry milk to the nipple) and lobules (glands that make milk). It occurs in both men and women, although male breast cancer is rare.

A mineral needed for healthy teeth, bones, and other body tissues. It is the most common mineral in the body. A deposit of calcium in body tissues, such as breast tissue, may be a sign of disease.

A mineral taken primarily as a supplement to prevent osteoporosis. It is also being studied for cancer prevention.

The individual unit that makes up the tissues of the body. All living things are made up of one or more cells.

An increase in the number of cells as a result of cell growth and cell division.

A type of research study that tests how well new medical approaches work in people. These studies test new methods of screening, prevention, diagnosis, or treatment of a disease. Also called clinical study.

A group of individuals who share a common trait, such as birth year. In medicine, a cohort is a group that is part of a clinical trial or study and is observed over a period of time.

Examination of the inside of the colon using a colonoscope, inserted into the rectum. A colonoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue to be checked under a microscope for signs of disease.

Cancer that develops in the colon (the longest part of the large intestine) and/or the rectum (the last several inches of the large intestine before the anus).

In science, a substance that is made up of more than one ingredient.

The process of identifying a disease, such as cancer, from its signs and symptoms.

The things a person eats and drinks.

A product that is added to the diet. A dietary supplement is taken by mouth, and usually contains one or more dietary ingredient (such as vitamin, mineral, herb, amino acid, and enzyme). Also called nutritional supplement.

In cancer, refers to how mature (developed) the cancer cells are in a tumor. Differentiated tumor cells resemble normal cells and tend to grow and spread at a slower rate than undifferentiated or poorly differentiated tumor cells, which lack the structure and function of normal cells and grow uncontrollably.

In medicine, refers to a part of the body that is farther away from the center of the body than another part. For example, the fingers are distal to the shoulder. The opposite is proximal.

A major component of fats that is used by the body for energy and tissue development.

In food, fiber is the part of fruits, vegetables, legumes, and whole grains that cannot be digested. The fiber in food may help prevent cancer. In the body, fiber refers to tissue made of long threadlike cells, such as muscle fiber or nerve fiber.

The stomach and intestines. The gastrointestinal tract is part of the digestive system, which also includes the salivary glands, mouth, esophagus, liver, pancreas, gallbladder, and rectum.

Higher than normal levels of calcium in the blood. Some types of cancer increase the risk of hypercalcemia.

The number of new cases of a disease diagnosed each year.

In medicine, a treatment or action taken to prevent or treat disease, or improve health in other ways.

The long, tube-shaped organ in the abdomen that completes the process of digestion. The intestine has two parts, the small intestine and the large intestine. Also called bowel.

A unit used to measure the activity of many vitamins, hormones, enzymes, and drugs. An IU is the amount of a substance that has a certain biological effect. For each substance there is an international agreement on the biological effect that is expected for 1 IU. Also called International Unit.

One of a pair of organs in the abdomen. Kidneys remove waste from the blood (as urine), produce erythropoietin (a substance that stimulates red blood cell production), and play a role in blood pressure regulation.

A condition in which the kidneys stop working and are not able to remove waste and extra water from the blood or keep body chemicals in balance. Acute or severe kidney failure happens suddenly (for example, after an injury) and may be treated and cured. Chronic kidney failure develops over many years, may be caused by conditions like high blood pressure or diabetes, and cannot be cured. Chronic kidney failure may lead to total and long-lasting kidney failure, called end-stage renal disease (ESRD). A person in ESRD needs dialysis (the process of cleaning the blood by passing it through a membrane or filter) or a kidney transplant. Also called renal failure.

A type of sugar found in milk and milk products.

One of a pair of organs in the chest that supplies the body with oxygen, and removes carbon dioxide from the body.

A measure of weight. A milligram is approximately 450,000 times smaller than a pound and 28,000 times smaller than an ounce.

In medicine, a mineral is a nutrient that is needed in small amounts to keep the body healthy. Mineral nutrients include the elements calcium, magnesium, and iron.

A federal agency in the U.S. that conducts biomedical research in its own laboratories; supports the research of non-Federal scientists in universities, medical schools, hospitals, and research institutions throughout the country and abroad; helps in the training of research investigators; and fosters communication of medical information. Access the National Institutes of Health Web site at http://www.nih.gov. Also called NIH.

A bundle of fibers that receives and sends messages between the body and the brain. The messages are sent by chemical and electrical changes in the cells that make up the nerves.

A health professional trained to care for people who are ill or disabled.

A measure of weight (one-sixteenth pound) and volume (one-eighth cup).

Cancer that forms in tissues of the ovary (one of a pair of female reproductive glands in which the ova, or eggs, are formed). Most ovarian cancers are either ovarian epithelial carcinomas (cancer that begins in the cells on the surface of the ovary) or malignant germ cell tumors (cancer that begins in egg cells).

Refers to a clinical study in which the control patients receive a placebo.

A growth that protrudes from a mucous membrane.

Having to do with the time after menopause. Menopause (“change of life”) is the time in a woman's life when menstrual periods stop permanently.

Having to do with the time before menopause. Menopause ("change of life") is the time of life when a woman's menstrual periods stop permanently.

In medicine, action taken to decrease the chance of getting a disease or condition. For example, cancer prevention includes avoiding risk factors (such as smoking, obesity, lack of exercise, and radiation exposure) and increasing protective factors (such as getting regular physical activity, staying at a healthy weight, and having a healthy diet).

Multiplying or increasing in number. In biology, cell proliferation occurs by a process known as cell division.

In medicine, a study or clinical trial in which participants are identified and then followed forward in time.

Cancer that forms in tissues of the prostate (a gland in the male reproductive system found below the bladder and in front of the rectum). Prostate cancer usually occurs in older men.

A molecule made up of amino acids that are needed for the body to function properly. Proteins are the basis of body structures such as skin and hair and of substances such as enzymes, cytokines, and antibodies.

In medicine, refers to a part of the body that is closer to the center of the body than another part. For example, the knee is proximal to the toes. The opposite is distal.

A study in which the participants are assigned by chance to separate groups that compare different treatments; neither the researchers nor the participants can choose which group. Using chance to assign people to groups means that the groups will be similar and that the treatments they receive can be compared objectively. At the time of the trial, it is not known which treatment is best. It is the patient's choice to be in a randomized trial.

Cancer that forms in the tissues of the rectum (the last several inches of the large intestine closest to the anus).

Checking for disease when there are no symptoms. Since screening may find diseases at an early stage, there may be a better chance of curing the disease. Examples of cancer screening tests are the mammogram (breast), colonoscopy (colon), Pap smear (cervix), and PSA blood level and digital rectal exam (prostate). Screening can also include checking for a person’s risk of developing an inherited disease by doing a genetic test.

A problem that occurs when treatment affects healthy tissues or organs. Some common side effects of cancer treatment are fatigue, pain, nausea, vomiting, decreased blood cell counts, hair loss, and mouth sores.

A product from a plant of Asian origin that produces beans used in many food products. Soy contains isoflavones (estrogen-like substances) that are being studied for the prevention of cancer, hot flashes that occur with menopause, and osteoporosis (loss of bone density). Soy in the diet may lower cholesterol levels and reduce the risk of heart disease. Also called Glycine max, soya, and soybean.

Describes a mathematical measure of difference between groups. The difference is said to be statistically significant if it is greater than what might be expected to happen by chance alone. Also called significant.

Adding nutrients to the diet.

A set of symptoms or conditions that occur together and suggest the presence of a certain disease or an increased chance of developing the disease.

A group or layer of cells that work together to perform a specific function.

A nutrient that the body needs in small amounts to function and stay healthy. Vitamin D helps the body use calcium and phosphorus to make strong bones and teeth. It is fat-soluble (can dissolve in fats and oils) and is found in fatty fish, egg yolks, and dairy products. Skin exposed to sunshine can also make vitamin D. Not enough vitamin D can cause a bone disease called rickets. It is being studied in the prevention and treatment of some types of cancer. Also called cholecalciferol.