
Calcium, along with vitamin D and vitamin B12, often comes up in discussions about supplements in hospitals and clinics. In this article, we’ll delve into calcium supplements — a topic surrounded by both awareness and confusion. Calcium plays a vital role not only in bone health but also in nerve function, hormone secretion, cardiovascular health, and muscle activity. While it’s encouraging to see growing awareness about calcium’s importance, many people remain unsure about how to meet their calcium needs.
Concerns about calcium supplements range from potential side-effects like constipation, bloating, and gastritis to fears about serious complications, such as kidney stones or calcium deposits in heart blood vessels leading to heart attacks. This begs the question: should we rely on calcium-rich foods or turn to supplements? And if supplements are necessary, how should they be taken? Let’s demystify this topic.
Understanding Calcium Metabolism
To answer these questions, it’s essential to grasp some basics about calcium metabolism. Calcium from food is absorbed primarily in the small intestine, and an acidic medium enhances this process. Once absorbed, about 99% of calcium is stored in the bones, with the remaining 1% circulating in the bloodstream to support other bodily functions. When calcium is needed by other systems, it is resorbed from the bones and transported via the blood. Excess calcium is excreted through urine or feces.
The body carefully regulates blood calcium levels through hormones like parathyroid hormone (PTH) and calcitonin, which are secreted by the parathyroid glands. However, the calcium levels in bones — reflected in bone mineral density — are not as tightly monitored. Vitamin D, phosphorus, and magnesium also play critical roles in calcium metabolism, acting as essential micronutrients for its proper utilization.
Who Needs Calcium?
The short answer: everyone. However, calcium requirements vary by age and gender.
- Before Age 50: Calcium needs are similar for men and women.
- After Age 50: Women, especially post-menopausal women, require slightly higher calcium intake due to the loss of estrogen, which affects bone density.
Fortunately, calcium is abundant in common foods such as milk, dairy products, soybeans, broccoli, figs, oranges, green leafy vegetables, and seafood. If your diet doesn’t consistently include these foods, calcium supplements may be necessary.
How Do Calcium Supplements Work?
Contrary to popular belief, calcium supplements don’t directly “fill the gaps” in bones like Lego blocks. Instead, they maintain optimal blood calcium levels, which reduces the need for calcium to be resorbed from bones. This indirectly lowers the risk of osteoporosis.
While it is possible to meet calcium needs through food alone, this requires careful attention to dietary intake and nutritional values — something many people struggle with in their busy lives.
How Much Calcium Is Needed?
The daily calcium requirement depends not only on quantity but also on the type of calcium and the stomach’s acidic environment during intake. The two most common forms of calcium supplements are:
1. Calcium Carbonate:
- Best absorbed in an acidic medium, so it should be taken after meals.
- Offers better absorption but may cause bloating, constipation, or gastritis in some individuals.
2. Calcium Citrate:
- Can be taken on an empty stomach, as it doesn’t rely on an acidic medium.
- A good option for those who experience gastrointestinal discomfort with calcium carbonate.
Research suggests limiting calcium supplementation to no more than 500 mg per day.
Food or Tablets?
The ideal source of calcium is food, as it is absorbed gradually throughout the day, allowing the body to regulate its metabolism effectively. Unlike supplements, which are consumed as a single bolus dose, calcium from food is less likely to cause complications like kidney stones or gastritis. Even patients with osteoporosis can meet their calcium needs through a diet rich in calcium, paired with appropriate osteoporosis treatments.
However, modern lifestyles often lead to diets high in carbohydrates and fats but lacking in essential nutrients like calcium. Cultural, social, and time constraints further contribute to these deficiencies, making calcium supplements a practical solution for many.
Special Considerations
Certain conditions, such as cancer, long-term steroid use, or other medical ailments, can impact calcium metabolism. Individuals with these conditions should consult their healthcare provider to determine the most suitable source and dosage of calcium.
Conclusion
Calcium is an essential nutrient that plays a critical role in overall health. While obtaining calcium through food is ideal, supplements can provide a necessary boost for those who struggle to meet their dietary needs. The choice between food and supplements ultimately depends on individual lifestyle, dietary habits, and medical conditions. Regardless of the source, maintaining adequate calcium levels is key to promoting bone health, preventing osteoporosis, and supporting overall well-being. After all, a strong foundation — both in bones and health — starts with calcium.

Dr. P. Keerthivasan
Consultant Orthopaedic Spine Surgeon,
Kauvery Hospital, Chennai