For instance, people who have a health condition that causes excess calcium in their bloodstream hypercalcemia should avoid calcium supplements. Too much or too little calcium, whether through diet or supplements, could be problematic for these individuals.

In this article, we briefly discuss daily human calcium requirements, types of calcium supplements, nutritional considerations of calcium, and problems with too little or too much calcium intake.

The two main forms of calcium supplements are carbonate and citrate. Calcium supplements contain several different kinds of calcium salts.

Each salt contains varying amounts of elemental calcium. In addition, some calcium supplements are combined with vitamin D or magnesium. Product labels should be read carefully and the supplement ingredients checked to see which form and amount of calcium are present in the product. This information is important if a person has any health or dietary concerns.

The daily requirement of calcium depends on age and sex. People should not take more than 1, mg of calcium a day in supplement form unless instructed by a doctor or dietitian. On average, the majority of Americans get between mg and mg of calcium daily through diet alone.

It is now known that vitamin D calciferol has a big role in calcium absorption. The requirements increase with age because older skin produces less vitamin D. These recommendations have since increased, as discussed below. Conditions associated with calcium deficiency include hypoparathyroidism, achlorhydria, chronic diarrhea, vitamin D deficiency, steatorrhea, sprue, pregnancy and lactation, menopause, pancreatitis, renal failure, alkalosis, and hyperphosphatemia.

Administration of certain drugs e. People who follow vegan diets, have lactose intolerance and limit dairy products, eat large amounts of protein or sodium, have osteoporosis, have undergone long-term treatment with corticosteroids, or have certain bowel or digestive diseases that decrease their ability to absorb calcium, such as inflammatory bowel disease or celiac disease, are also at risk for low calcium intake.

In these situations, calcium supplements may help people meet their calcium requirements. Some other natural sources of calcium are coral calcium and oyster shell calcium.

Coral calcium is a form of calcium carbonate that comes from fossilized coral sources. The human body undergoes a natural process known as chelating , in which it combines calcium with another material e.

Coral calcium is also used in maxillofacial surgery and bone grafting. Calcium and Vitamin D: A major role of vitamin D is to help the body absorb calcium and maintain bone density.

For this reason, some calcium supplements are combined with vitamin D. This vitamin is available in two forms, vitamin D 2 ergocalciferol and vitamin D 3 cholecalciferol. The D 2 form of the vitamin has a shorter shelf life compared to the D 3 form. A few foods are known to have small amounts of vitamin D, such as canned salmon with bones and egg yolks.

Vitamin D can also be acquired from fortified foods and produced naturally through sun exposure. Calcitriol Rocaltrol is the biologically active form of vitamin D that is used to treat and prevent low levels of calcium in the blood of patients whose kidneys or parathyroid glands are not functioning normally.

Calcium and Vitamin K 2 : Vitamin K 2 has several isoforms or analogues called MK-4 to MK This vitamin provides major protection from osteoporosis and pathologic calcification of the arteries and soft tissues—a major known consequence of aging.

Vitamin K 2 is found in animals and bacteria, including beneficial probiotic bacteria from the gastrointestinal tract. Antibiotics interfere with normal growth of healthy bacteria and impact vitamin K 2 production.

Although vitamin D 3 has been known as the bone vitamin because it puts the osteocalcin gene into action and acts swiftly on bones, the slower-acting vitamin K 2 has been recognized as being just as important for bone maintenance.

The human skeleton is fully replaced every 8 to 10 years with good, dense bone, and these two vitamins play a large role in the process. The oral osteoporosis treatment dose of vitamin K 2 is 45 mg a day. Elemental Calcium: Elemental calcium is what the body absorbs for bone growth and other health benefits; therefore, the actual amount of calcium in the supplement is very important.

The label on calcium supplements is helpful in determining how much calcium is contained in one serving number of tablets. Supplement Choice: Some people cannot tolerate certain calcium supplements owing to side effects such as gas, constipation, and bloating.

One may need to try a few different brands or types of calcium supplement to find the one that he or she can tolerate best. In general, calcium carbonate is the most constipating supplement, but it contains the highest amount of calcium and is the least expensive.

Calcium phosphate does not cause gas or constipation, but it is more expensive than calcium carbonate. Calcium citrate is the most easily absorbed and does not require stomach acid for absorption, but it is expensive and does not contain much elemental calcium.

Women should meet their calcium needs through both their diet and supplements. Calcium supplements are available in a variety of dosage forms, including chewable tablets, capsules, liquids, and powders.

Individuals who have trouble swallowing tablets can use chewable or liquid calcium supplements. Drug Interactions: Calcium supplements may interact with many different prescription medications, including blood pressure medications calcium channel blockers , synthetic thyroid hormones, bisphosphonates, and antibiotics.

Pharmacists are the best professionals to consult about possible drug interactions and for calcium supplement recommendations. Bioavailability: The human body must be able to absorb calcium so that it is bioavailable and effective.

Calcium supplements should be taken in small doses mg at a time and preferably at mealtime to increase absorption. Cost and Quality: The Federal Trade Commission holds supplement manufacturers responsible for ensuring that their supplements are safe and their claims are truthful.

Many companies may have their products independently tested based on the U. Pharmacopeia USP standards. Supplements that bear the USP abbreviation meet standards for quality assurance. Some concerns have been raised about the potential adverse effects of high calcium intake on cardiovascular health among the elderly due to calcification of the arteries and veins.

There are several possible pathophysiological mechanisms for these effects, which include effects on vascular calcification, function of vascular cells, and blood coagulation.

However, newer studies have found no increased risk of heart attack or stroke among women taking calcium supplements during 24 years of follow-up.

Some scientists believe that because calcium supplements produce small reductions in fracture risk and a small increase in cardiovascular risk, there may be no net benefits from their use.

They claim that since food sources of calcium appear to produce similar benefits on bone density and have not been associated with adverse cardiovascular effects, they may be preferable to supplements. More studies are required to prospectively analyze the effect of calcium or calcium plus vitamin D supplementation beyond bone health.

The medical community is still uncertain as to the effects of calcium supplements in women. Calcium deposits can be found in many parts of the body at higher ages.

A coronary calcium scan is typically done to check for the buildup of calcium in plaque on the walls of the arteries of the heart. Coronary calcium scan scores range from 0 to more than A calcium score of zero means no identifiable plaque, while a score of above indicates extensive atherosclerotic plaque and significant coronary narrowing.

Calcification of the breast is often seen in women above the age of 50 years. Calcium deposits are easily detected by x-ray images because calcification is composed of calcium phosphate, similar to that in bone.

Although calcium is abundant in dairy products like milk, the amount of calcium that we need increases as we age. Since many people quit eating or drinking food products with calcium, such as whole milk, due to a health-related diet, a dietary supplement with calcium is important.

Older adults require approximately 1, milligrams of calcium per day. The remainder of this article addresses ways to get enough calcium to keep bones strong. The healthiest sources of calcium are from foods that are rich in calcium, including most dairy products, cheeses, fortified orange juice and leafy green vegetables, which can provide at least milligrams of calcium.

A balanced diet provides most calcium needed by older adults. However, additional calcium must be ingested to reach a required 1, milligrams per day. The body can handle more than the minimum requirement of calcium. However, the body cannot manufacture calcium if too little is ingested.

All calcium ingested is not absorbed into the body. The small intestine, which is the part of the digestive system just beyond the stomach, is where calcium is taken by the blood and transported to bone and other tissues. The amount of calcium absorbed is dependent on several key factors:.

Calcium typically comes as a liquid or tablet carbonate or citric acid preparation. The carbonate requires acid in the intestine that generally is generated with food in the stomach. Therefore, carbonate pills should be taken with meals by people taking calcium to increase calcium absorption.

Calcium citrate is soluble and does not require meals for absorption. Most commonly used calcium supplements come as a carbonate form and should be taken during or immediately after meals. Check the label of your calcium supplement to determine which form you have and when to take it.

Approximately milligrams of calcium can be taken at one time. Therefore, do not take all supplements at the same time. If you and your doctor have agreed you need supplementation, be sure to take it three times a day or approximately one-third at a time. To avoid taking too much, do not take more than 2, milligrams per day.

Vitamin D also is required for calcium absorption. The best source of vitamin D is sunshine for approximately 20 minutes per day, which is not a problem for most people who live in the South.

There are several possible pathophysiological mechanisms for these effects, which include effects on vascular calcification, function of vascular cells, and blood coagulation. However, newer studies have found no increased risk of heart attack or stroke among women taking calcium supplements during 24 years of follow-up.

Some scientists believe that because calcium supplements produce small reductions in fracture risk and a small increase in cardiovascular risk, there may be no net benefits from their use.

They claim that since food sources of calcium appear to produce similar benefits on bone density and have not been associated with adverse cardiovascular effects, they may be preferable to supplements.

More studies are required to prospectively analyze the effect of calcium or calcium plus vitamin D supplementation beyond bone health. The medical community is still uncertain as to the effects of calcium supplements in women.

Calcium deposits can be found in many parts of the body at higher ages. A coronary calcium scan is typically done to check for the buildup of calcium in plaque on the walls of the arteries of the heart. Coronary calcium scan scores range from 0 to more than A calcium score of zero means no identifiable plaque, while a score of above indicates extensive atherosclerotic plaque and significant coronary narrowing.

Calcification of the breast is often seen in women above the age of 50 years. Calcium deposits are easily detected by x-ray images because calcification is composed of calcium phosphate, similar to that in bone. Coronary calcium is part of the development of atherosclerosis; it occurs exclusively in atherosclerotic arteries and is absent in normal vessel walls.

The amount of calcium in the walls of the coronary arteries, assessed by a calcium score, appears to be a better cardiovascular disease risk predictor than standard factors. Risks of Low Calcium Intake: As mentioned above, calcium is important for healthy bones and teeth, as well as for normal muscle and nerve function.

There are health problems associated with low calcium levels: Children may not reach their full potential adult height, and adults may have low bone mass, which is a risk factor for osteoporosis and hip fracture.

Normal blood calcium levels are maintained through the actions of parathyroid hormone, the kidneys, and the intestines. The normal adult value for serum calcium is 4. Only ionized calcium is transported into cells and metabolically active.

Decreases in the ionized free fraction of calcium cause various symptoms. Hypocalcemia, or low-level calcium, most commonly occurs with low calcium absorption, vitamin D or K 2 deficiency, chronic renal failure, and hypoparathyroidism.

Risks of High Calcium Intake: Many factors can increase blood calcium levels. Although the body has a built-in regulatory process for calcium absorption and maintenance, underlying diseases, medication interactions, or overuse of supplements can cause high calcium levels.

An abnormally high calcium concentration can cause damaging health problems and requires medical treatment. Although dietary calcium is generally safe, excessive calcium does not provide extra bone protection. In fact, if calcium from diet and supplements exceeds the tolerable upper limit, it could cause kidney stones, prostate cancer, constipation, calcium buildup in blood vessels, and impaired absorption of iron and zinc.

Taking calcium supplements and eating calcium-fortified foods may increase calcium above normal levels. As a result, it is very important to stick to the RDA and not exceed the recommended dosage. The best way to treat calcium deficiency is to prevent its occurrence.

Modification of risk factors is imperative, and pharmacists can play a large role in this area. They can recommend appropriate calcium and vitamin D supplements. Individuals, particularly women, at risk of low calcium should take foods and drinks rich in calcium and vitamin D, quit smoking, and increase weight-bearing and muscle-strengthening exercise.

Bailey RL, Dodd KW, Goldman JA, et al. Estimation of total usual calcium and vitamin D intakes in the United States. J Nutr ; 4 Straub DA.

Calcium supplementation in clinical practice: a review of forms, doses, and indication, Nutr Clin Pract. Xiao Q, Murphy RA, Houston DK, et al.

Dietary and supplemental calcium intakes in relation to mortality from cardiovascular diseases in the NIH-AARP Diet and Health Study. JAMA Intern Med.

Bunyardatavej N, Buranasinsup S. J Med Assoc Thai. Saljoughian M. The emerging role of vitamin K 2. US Pharm. Baun L, Russell TM. Overview of the management of osteoporosis in women. Hsia J, Heiss G, Ren H, et al. Vascular calcification and bone disease: the calcification paradox.

Trends Mol Med. Otton JM, Lonborg JT, Boshell D, et al. A method for coronary artery calcium scoring using contrast-enhanced computed tomography.

J Cardiovasc Comput Tomogr. National Institutes of Health, Office of Dietary Supplements. Dietary supplement fact sheet: calcium. Accessed May 30, Pharmacy Practice Affordable Medicines Biosimilars Compliance Compounding Drug Approvals. COVID Dermatology Diabetes Gastroenterology Hematology.

mRNA Technology Neurology Oncology Ophthalmology Orthopedics. Featured Issue Featured Supplements. COVID Resources. Types of Calcium Supplements The two main forms of calcium supplements are carbonate and citrate.

Calcium is found in dairy products and in a variety of nondairy products, including dark green leafy vegetables, grains, figs, fish with soft bones, and calcium-fortified foods. Even with healthy eating and a balanced diet, one may not get enough calcium daily.

Calcium Supplementation and Cardiovascular Effects Some concerns have been raised about the potential adverse effects of high calcium intake on cardiovascular health among the elderly due to calcification of the arteries and veins.

To comment on this article, contact editor uspharmacist. January In This Issue Digital Magazine Archives Subscription. Related Content.

Depending on its strength, each chewable pill or soft chew provides about to mg of calcium [ 14 ]. A substantial proportion of people in the United States consume less than recommended amounts of calcium.

Average daily intakes of calcium from foods and beverages are 1, mg for men age 20 and older and mg for women [ 18 ]. For children age 2—19, mean daily intakes of calcium from foods and beverages range from to 1, mg [ 18 ]. Average daily calcium intakes from both foods and supplements are 1, mg for men, 1, mg for women, and to 1, mg for children [ 18 ].

Poverty is also associated with a higher risk of inadequacy. NHANES data from to show that the risk of inadequate calcium intakes less than to 1, mg is Calcium deficiency can reduce bone strength and lead to osteoporosis, which is characterized by fragile bones and an increased risk of falling [ 1 ].

Calcium deficiency can also cause rickets in children and other bone disorders in adults, although these disorders are more commonly caused by vitamin D deficiency.

In children with rickets, the growth cartilage does not mineralize normally, which can lead to irreversible changes in the skeletal structure [ 1 ].

Another effect of chronic calcium deficiency is osteomalacia, or defective bone mineralization and bone softening, which can occur in adults and children [ 1 ].

For rickets and osteomalacia, the requirements for calcium and vitamin D appear to be interrelated in that the lower the serum vitamin D level measured as hydroxyvitamin D [25 OH D] , the more calcium is needed to prevent these diseases [ 21 ].

Hypocalcemia serum calcium level less than 8. Hypocalcemia can be asymptomatic, especially when it is mild or chronic [ 23 ]. When signs and symptoms do occur, they can range widely because low serum calcium levels can affect most organs and symptoms [ 24 ].

The most common symptom is increased neuromuscular irritability, including perioral numbness, tingling in the hands and feet, and muscle spasms [ 23 ]. More severe signs and symptoms can include renal calcification or injury; brain calcification; neurologic symptoms e.

Menopause leads to bone loss because decreases in estrogen production reduce calcium absorption and increase urinary calcium loss and calcium resorption from bone [ 1 ]. Over time, these changes lead to decreased bone mass and fragile bones [ 1 ]. The calcium RDA is 1, mg for women older than 50 years vs.

People with lactose intolerance, those with an allergy to milk, and those who avoid eating dairy products including vegans have a higher risk of inadequate calcium intakes because dairy products are rich sources of calcium [ 1 , 27 ].

Options for increasing calcium intakes in individuals with lactose intolerance include consuming lactose-free or reduced-lactose dairy products, which contain the same amounts of calcium as regular dairy products [ 1 , 3 ].

Those who avoid dairy products because of allergies or for other reasons can obtain calcium from nondairy sources, such as some vegetables e. However, these individuals typically need to eat foods fortified with calcium or take supplements to obtain recommended amounts [ 28 ].

This section focuses on six health conditions and diseases in which calcium might play a role: bone health in older adults, cancer, cardiovascular disease CVD , preeclampsia, weight management, and metabolic syndrome.

Bone is constantly being remodeled. Declining levels of estrogen in women during menopause and for approximately 5 years afterward lead to rates of bone resorption that are higher than rates of bone formation, resulting in a rapid decrease in bone mass [ 7 ]. Over time, postmenopausal women can develop osteoporosis, in which bone strength is compromised because of lower BMD and bone quality [ 1 ].

Age-related bone loss can also occur in men and lead to osteoporosis, but fracture risk tends to increase in older men about 5 to 10 years later than in older women [ 1 ].

Osteoporosis increases the risk of fractures, especially of the hip, vertebrae, and forearms [ 1 , 7 ]. FDA has approved a health claim for the use of supplements containing calcium and vitamin D to reduce the risk of osteoporosis [ 29 ].

However, not all research supports this claim. In spite of the importance of calcium in bone health, observational evidence is mixed on the link between calcium intakes and measures of bone strength in older adults.

Support for such a link comes from an analysis of — NHANES cross-sectional data on 2, adults age 60 and older Results were similar in of the women who were followed for 6 years, even though mean daily intakes of calcium dropped by an average of 40 mg during this period.

Some but not all clinical trials have found that calcium supplementation can improve bone health in older adults. On average, women lost 1.

Several recent systematic reviews and meta-analyses have found that supplementation with calcium alone or a combination of calcium and vitamin D increases BMD in older adults. For example, a systematic review and meta-analysis included 15 RCTs in postmenopausal women but did not include the two studies described in the previous paragraph in 78, women, of which 37, were in the intervention group and 40, were in the control group [ 34 ].

Supplementation with both calcium and vitamin D or consumption of dairy products fortified with both nutrients increased total BMD as well as BMD at the lumbar spine, arms, and femoral neck.

However, in subgroup analyses, calcium had no effect on femoral neck BMD. Earlier systematic reviews and meta-analyses found a positive relationship between calcium and vitamin D supplementation and increased BMD in older males [ 35 ] and between higher calcium intakes from dietary sources or supplements and higher BMD in adults older than 50 [ 25 ].

However, whether these BMD increases were clinically significant is not clear. As with the evidence on the link between increased calcium intakes and reductions in BMD loss, the findings of research on the use of calcium supplementation to prevent fractures in older adults are mixed.

For the most part, the observational evidence does not show that increasing calcium intakes reduces the risk of fractures and falls in older adults. For example, a longitudinal cohort study of 1, women age 42 to 52 years at baseline who were followed for 10—12 years found that fracture risk was not significantly different in calcium supplement users some of whom also took vitamin D supplements and nonusers, even though supplement use was associated with less BMD loss throughout the study period [ 36 ].

Some clinical trial evidence shows that supplements containing a combination of calcium and vitamin D can reduce the risk of fractures in older adults. However, findings were negative in another systematic review and meta-analysis that included 14 RCTs of calcium supplementation and 13 trials comparing calcium and vitamin D supplements with hormone therapy, placebo, or no treatment in participants older than 50 years [ 38 ].

The results showed that calcium supplementation alone had no effect on risk of hip fracture, and supplementation with both calcium and vitamin D had no effect on risk of hip fracture, nonvertebral fracture, vertebral fracture, or total fracture.

Similarly, a systematic review of 11 RCTs in 51, adults age 50 and older found that supplementation with vitamin D and calcium for 2 to 7 years had no impact on risk of total fractures or of hip fractures [ 39 ].

Preventive Services Task Force USPSTF concluded with moderate certainty that daily doses of less than 1, mg calcium and less than IU 10 mcg vitamin D do not prevent fractures in postmenopausal women and that the evidence on larger doses of this combination is inadequate to assess the benefits in this population [ 40 ].

The USPSTF also determined the evidence on the benefits of calcium supplementation alone or with vitamin D to be inadequate to assess its effect on preventing fractures in men and premenopausal women.

Additional research is needed before conclusions can be drawn about the use of calcium supplements to improve bone health and prevent fractures in older adults.

Calcium might help reduce the risk of cancer, especially in the colon and rectum [ 1 ]. However, evidence on the relationship between calcium intakes from foods or supplements and different forms of cancer is inconsistent [ 4 ].

Most clinical trial evidence does not support a beneficial effect of calcium supplements on cancer incidence.

A 4-year study of 1, mg calcium and 2, IU 50 mcg vitamin D or placebo daily for 4 years in 2, healthy women age 55 years and older showed that supplementation did not reduce the risk of all types of cancer [ 41 ].

The large WHI study described above also found no benefit of supplemental calcium and vitamin D on cancer incidence [ 42 ]. In addition, a meta-analysis of 10 RCTs that included 10, individuals who took supplements containing mg calcium or more without vitamin D for a mean of 3.

However, one large clinical trial did find that calcium supplements reduce cancer risk. In this 4-year trial, by the same investigators as the 4-year trial above, 1, women age 55 years or older in Nebraska took 1, to 1, mg calcium alone; 1, to 1, mg calcium plus 1, IU Some scientists have questioned these findings because of the lack of statistical power the studies were designed to detect differences in bone health measures, not cancer incidence , details from the investigators on the study sample, and randomization procedures [ 45 , 46 ].

Observational evidence does not support an association between higher calcium intakes and a lower risk of cancer mortality. An analysis of data on , participants in the Cancer Prevention Study II Nutrition Cohort, who were followed for an average of A systematic review and meta-analysis of 22 observational studies in 2,, participants age 8 and older followed for 4.

Clinical trials have also not shown that supplemental calcium alone or combined with vitamin D has an impact on risk of mortality from all cancers. Rates of cancer incidence and cancer mortality did not differ between those who did and those who did not receive calcium supplements.

In the WHI trial, 36, postmenopausal women were randomly assigned to daily supplementation with a combination of 1, mg calcium and IU 10 mcg vitamin D3 or placebo [ 42 ].

After an average of 7 years, risk of cancer mortality did not differ between groups. The meta-analysis of 10 RCTs that included 10, individuals described above found no impact of calcium supplementation on cancer mortality rates [ 43 ].

A substantial body of evidence has addressed the role of calcium in preventing colorectal cancer or its precursor, adenomas. Much but not all of the observational evidence supports a link between higher calcium intakes and lower risk of colorectal cancer. A cohort study in 77, adults found that over a mean of 7.

Findings were similar for dietary intakes of calcium in two other meta-analyses [ 52 , 53 ]. In spite of the observational evidence supporting an association between higher calcium intakes and lower colorectal cancer risk, clinical trials investigating calcium supplements for prevention of colorectal cancer or adenomas have had mixed results.

A follow-up study by Cauley and colleagues evaluated outcomes 4. Colorectal cancer rates did not differ between groups.

Several observational studies have shown that the risk of prostate cancer might be higher with higher calcium intakes, but possibly only when the calcium comes from dairy foods. In an analysis of data from 2, men who participated in the French SU.

MAX Supplementation en Vitamines et Minéraux Antioxydants prospective study and were followed for an average of 7. The risk was 2. However, in analyses of results for various sources of calcium, only calcium from dairy foods was significantly associated with prostate cancer risk 2.

A meta-analysis included 15 epidemiological studies of calcium intake and ovarian cancer risk in , women who developed 7, cases of ovarian cancer [ 59 ].

However, the difference in risk was not statistically significant when both dietary and supplemental calcium intakes were considered. For breast cancer, observational studies have had mixed findings on whether higher calcium intakes are associated with a lower risk.

However, the WHI described above found similar incidence rates of invasive breast cancer in the supplement and placebo groups [ 61 ].

Additional well-designed randomized trials are needed to determine whether dietary or supplemental calcium intakes increase, decrease, or have no effect on risk of cancer in general or of specific types of cancer, or on cancer mortality. Calcium binds fatty acids, so it can reduce lipid absorption and might therefore lower CVD risk [ 1 , 4 ].

However, the findings from research on the role of dietary calcium and calcium supplements in reducing CVD have been mixed, and some evidence indicates that calcium supplements might even increase CVD risk. Several large observational studies have shown an association between lower calcium intakes and higher risk of hypertension, stroke, and atherosclerosis.

This association was strongest in women, adults age 20—44 years, those who did not have diabetes, and especially women age 20—44 years. However, the study found no association between calcium intakes and risk of CVD mortality or myocardial infarction.

Furthermore, a systematic review and meta-analysis that included 27 observational studies found no consistent dose-response relationships between total, dietary, or supplemental calcium intakes and CVD mortality [ 65 ].

Evidence on dose-response relationships between calcium intakes and risk of stroke or stroke mortality was inconsistent. A diet containing more calcium than the typical U. diet because of added low-fat or nonfat dairy products lowered systolic blood pressure by an average of 5.

However, this Dietary Approaches to Stop Hypertension DASH diet also increases intakes of other nutrients, such as potassium and magnesium, that are associated with reductions in blood pressure, so any independent contribution of calcium cannot be determined.

Some clinical trials have shown that calcium supplements are associated with decreased hypertension risk or decreased cholesterol levels, but others have had more mixed findings. A Cochrane Review of 16 trials in 3, adults with a median follow-up period of 3.

Findings were mixed in two analyses of data from the WHI. In another secondary analysis of data on 16, WHI participants, the supplements had no association with atrial fibrillation risk [ 70 ].

Similarly, an evidence report and systematic review conducted for the USPSTF that included 11 RCTs of vitamin D, calcium, or both for 2 to 7 years in 51, adults age 50 years and older found that supplementation with vitamin D alone or combined with calcium had no effect on CVD incidence [ 39 ].