In middle-aged and older adults, the probability of developing high blood pressure, also known as hypertension, is a staggering 90% (1;2). This is especially concerning when we consider the facts about high blood pressure. First, approximately 46% of adults with high blood pressure do not know that they have it. Second, only about 42% of adults receive a formal diagnosis and treatment. Third, this translates into just 1 in 5 adults with high blood pressure having their condition under control (3).
Why is having elevated blood pressure so bad? High blood pressure is a risk factor for developing many other diseases and conditions—such as those related to the kidneys, heart, and brain—and is a driver of premature death across the globe (1-3). Despite this seemingly bleak picture, there is cause for optimism because high blood pressure is a modifiable risk factor (1;4). This means that we can take action to avoid having high blood pressure.
Over the past four decades, various studies have looked into the presence of a link between calcium intake and blood pressure (5-12). More recently, a systematic review investigated calcium supplements and foods fortified with calcium as potential strategies for preventing hypertension that is not caused by a medical condition. These strategies, which are deemed accessible and affordable, were studied in people with normal blood pressure. Within the review, calcium supplementation included taking a calcium tablet orally, or consuming fortified foods, such as high-calcium skim milk or juice with added calcium (5).
So, should you add calcium supplements or fortified foods to your shopping list?
What the research tells us
Overall, the review found that increasing calcium intake decreases systolic and diastolic blood pressure by a small amount in people with normal blood pressure. Although the reductions are modest, the findings are still important. This is especially true when we consider that even small decreases in blood pressure can help lower the risk of developing diseases that affect the blood vessels. What is more, we see positive results for blood pressure in men and women, as well as in people under and over the age of 35. Although it is worth noting that younger folks tend to see greater reductions in blood pressure.
When we break down the strategies used to increase calcium intake, we do see some differences by strategy type and dose. For instance, it appears that calcium tablets effectively decrease blood pressure, while food fortification does not. However, we cannot conclusively speak to how these different strategies compare because the number of studies included in the review overwhelmingly focused on supplement use. In terms of dosage, calcium intake of 1500 mg or higher per day appears to produce greater decreases in blood pressure than intake of 1000 mg of calcium per day.
The safety of calcium intake was another focus of the review. The review found that no adverse side effects, especially those of specific concern to calcium supplementation and excess calcium—such as kidney stones, heart attack, stroke, anemia, iron deficiency, and death—were reported. In summary, the results illustrate that increased calcium intake can potentially help to thwart the development of hypertension by lowering blood pressure. However, more research is needed to determine the most effective and safe calcium intake strategy (5).
While these results are positive and may offer some folks another strategy to stave off high blood pressure, it is essential to remember that not all supplements are safe for everyone. Before you start a new supplement, consult your health care team about its potential benefits and harms given your specific circumstances.
