Calcium is vital for maintaining strong bones and teeth, and plays a crucial role in various bodily functions, including blood clotting, muscle contraction, and nerve function. Knowing What Are Calcium Rich Foods is essential for ensuring you meet your daily requirements and maintain optimal health. This guide explores the best food sources of calcium, their bioavailability, and the benefits of incorporating them into your diet.
Calcium is primarily stored in bones (99%), with the remaining 1% distributed in blood, muscles, and other tissues. To support these vital functions, your body strives to maintain a consistent calcium level in your blood and tissues. When calcium levels dip too low, the parathyroid hormone (PTH) signals bones to release calcium into the bloodstream. PTH also stimulates vitamin D production to enhance calcium absorption in the intestines while reducing calcium excretion by the kidneys. Conversely, when calcium levels are sufficient, calcitonin, another hormone, lowers blood calcium levels by inhibiting calcium release from bones and increasing its excretion in urine.
Assortment of calcium-rich foods including cheese, nuts, broccoli, canned fish, and milk, on a wooden board
Your body obtains calcium through consuming calcium-rich foods or supplements, and by drawing from its calcium reserves. Insufficient dietary calcium leads to the body extracting it from bones. Ideally, this “borrowed” calcium should be replenished later, but this doesn’t always happen, even with increased calcium intake.
Recommended Daily Calcium Intake
Here’s a breakdown of the recommended daily calcium intake:
- Women (19-50 years): 1,000 mg
- Women (51+ years): 1,200 mg
- Pregnant and lactating women: 1,000 mg
- Men (19-70 years): 1,000 mg
- Men (71+ years): 1,200 mg
Calcium and Health: Benefits and Considerations
Calcium’s role extends beyond bone health. It influences blood pressure, cardiovascular health, and even the risk of certain cancers. Here’s a closer look:
Blood Pressure
Some studies suggest a potential link between total calcium intake (from food and supplements) and lower high blood pressure. However, due to limitations in study designs, increasing calcium intake beyond the Recommended Dietary Allowance (RDA) is not yet a definitive treatment recommendation for hypertension. Larger, longer-term trials are necessary to confirm whether increased calcium intake or supplementation can effectively lower high blood pressure.
Cardiovascular Disease
There have been concerns raised about calcium supplements and heart health, with some research indicating an increased risk of cardiovascular events associated with their use. High-dose supplements may cause hypercalcemia (toxic levels of calcium in the blood), potentially leading to blood clots or arterial hardening. However, a clinical guideline from the National Osteoporosis Foundation and the American Society for Preventive Cardiology suggests that calcium from food or supplements has no relationship (beneficial or harmful) to cardiovascular disease in generally healthy adults. It’s generally advised not to exceed the Upper Limit for calcium, which is 2,000-2,500 mg daily from both food and supplements.
Bone Health
Calcium is essential for maintaining bone health throughout life. Bones are constantly being remodeled, with osteoblasts building bone and osteoclasts breaking it down. In healthy individuals, bone production exceeds destruction until around age 30, after which destruction typically exceeds production, potentially leading to bone loss. Adequate dietary calcium can help slow bone loss, but it might not completely prevent it. Calcium absorption tends to decrease with age, so high calcium intake doesn’t always resolve the issue.
Colorectal Cancer
Some epidemiological studies suggest that high calcium intake may have a protective effect against colorectal cancer. Randomized controlled trials involving calcium supplements have yielded mixed results. A Cochrane review found that taking 1,200 mg of elemental calcium daily for about 4 years reduced the incidence of new colorectal adenomas. The World Cancer Research Fund and the American Institute for Cancer Research suggest that calcium supplements exceeding 200 mg daily and high-calcium dairy foods are likely to decrease the risk of colorectal cancer. This may be due to calcium’s ability to bind to toxic substances in the colon and inhibit tumor cell growth, and the presence of protective bacteria in dairy foods.
Kidney Stones
Contrary to previous beliefs, not eating enough calcium-rich foods can increase the risk of kidney stone formation. Research indicates that a high intake of calcium-rich foods can decrease the risk of kidney stones in women, although calcium supplements might increase the risk. Calcium-rich foods, particularly dairy, reduce the absorption of oxalates, which contribute to calcium-oxalate stones.
Food Sources: What Are Calcium Rich Foods?
Calcium is abundant in a variety of foods, not just dairy products. Here’s a comprehensive list of what are calcium rich foods:
- Dairy: Milk, cheese, yogurt (excellent sources with good bioavailability)
- Leafy Greens: Kale, collard greens, bok choy (high bioavailability, but spinach has lower bioavailability due to oxalates)
- Fortified Foods: Calcium-fortified orange juice, cereals, plant-based milks (good alternatives for those avoiding dairy)
- Fish with Edible Bones: Sardines, canned salmon (excellent sources if you consume the bones)
- Beans and Legumes: White beans, soybeans, tofu (calcium-set tofu)
- Nuts and Seeds: Almonds, chia seeds (lower bioavailability compared to dairy and some leafy greens)
Bioavailability of Calcium
Bioavailability refers to the amount of calcium that is absorbed and used by the body. Dairy foods typically have a bioavailability of about 30%. Plant foods like bok choy contain less calcium overall but have a higher bioavailability, around 50%. Some plant foods contain oxalates and phytates, “anti-nutrients” that bind to calcium and decrease its bioavailability.
Deficiency and Toxicity of Calcium
Maintaining balanced calcium levels is crucial for overall health.
Deficiency
Calcium deficiency, or hypocalcemia, can result from kidney failure, digestive tract surgeries, or certain medications. Symptoms include muscle cramps, numbness, abnormal heart rate, and poor appetite. Long-term deficiency can lead to osteopenia and osteoporosis. Individuals at risk include postmenopausal women, those with amenorrhea, and those with milk allergies or lactose intolerance.
Toxicity
Excess calcium in the blood, known as hypercalcemia, can result from excessive supplementation. The Upper Limit (UL) for calcium is 2,500 mg daily from food and supplements. Symptoms include weakness, nausea, shortness of breath, and heart palpitations. High doses of calcium can also interfere with the absorption of other minerals like iron and zinc.
Optimizing Calcium Intake: Key Takeaways
Knowing what are calcium rich foods is just the first step. Here’s how to optimize your calcium intake:
- Prioritize calcium-rich foods: Include a variety of dairy, leafy greens, fortified foods, and other sources in your diet.
- Consider bioavailability: Be mindful of bioavailability when choosing calcium sources, especially if you have dietary restrictions.
- Balance supplement use: Consult with your doctor or a registered dietitian before taking calcium supplements to determine the appropriate dosage and form.
- Avoid excessive intake: Stay within the recommended daily limits to prevent hypercalcemia and potential health risks.
- Be aware of interactions: Understand how certain nutrients and medications can affect calcium absorption and adjust your diet accordingly.
By understanding what are calcium rich foods and how to optimize your calcium intake, you can support strong bones, healthy bodily functions, and overall well-being.
