Focus on calcium

What is calcium?

Calcium is the most abundant mineral in the body. The adult human body contains around 1kg of calcium. 99% of the calcium can be found in bones and teeth where it plays a structural role. The rest of the calcium is needed for the proper functioning of the nervous system, heart, muscles, and for the release of hormones.

Bone is a living tissue, constantly getting remodelled to ensure adequate calcium levels in our body. High calcium levels will lead to bone formation, while a calcium deficiency leads to the breakdown of bones and calcium release. Calcium deficiency can lead to several diseases:

• Osteoporosis occurs when the bone becomes less dense hence porous which leads to fragile bones and increases the risk of fractures.
• Rickets happens in children when lack of calcium induces improper mineralisation of the bone matrix. As a result, bones lack proper structure and become soft and weak.
• Osteomalacia causes improper mineralisation of the bone matrix resulting in soft bones in adults.

Deficiency in calcium is not the only reason for bone mass loss. After the age of 30, the bone mass naturally starts to slowly decrease. In women, the peak bone density is lower than men and the rate of bone density loss is higher, which results in women being more likely to develop osteoporosis than men.

Dietary recommendations

Recommendations vary across countries but generally advise for adults a daily calcium intake of 1000 mg. During the teenage years, the recommendation is 1300mg/day to ensure proper bone density during peak bone growth.

After the age of 50 in women and 70 in men it is recommended to consume 1200mg to limit the rate of bone loss.

It is best to consume calcium through the diet rather than supplementation whenever possible so as to avoid excessive calcium consumption. While an adequate calcium intake is important, an excess of this nutrient in the body can lead to higher risks of heart disease and low levels of other minerals such as phosphate or iron. The safe upper limit of calcium consumption in adults is 2500mg per day.

Food sources of calcium

Calcium can be found in a variety of foods from both plant and animal sources such as nuts, seeds, beans, leafy greens, canned fish (sardines), mineral water and of course dairy. Dairy sources of calcium are the most bioavailable sources. This is due to the presence in dairy of other nutrients essential to bone health like phosphorus and vitamin D.

Dairy is the most important source of dietary calcium and accounts for 75% of the calcium intake in Europe and north America.

After eating, calcium is absorbed in the small intestine through passive and active absorption. The active absorption pathway is modulated by vitamin D. Vitamin D and calcium go hand in hand for bone health.

Calcium in dairy

Dairy naturally contain quite high levels of calcium that is highly bioavailable.

Yogurt as a dairy product is a good source of calcium. On top of that, the presence of probiotic bacteria in yogurt may be beneficial for bone health by modifying the gut microbiota and increasing the absorption of calcium. They also help the immune system and protect against inflammation which might help in reducing the rate of bone loss. This makes yogurt and other fermented dairy an interesting source of calcium for bone health.

Research found that yogurt promotes healthy growth and higher bone mineral density in children consuming yogurt compared to non-yogurt consumers.

Yogurt consumption is also associated with lowers risks of osteoporosis in older age. It was found that yogurt consumers had stronger bones than non-yogurt consumers and increasing one serving of yogurt per week was associated with a 39% decrease in osteoporosis in women and 54% in men.

Yogurt and dairy products are a rich in protein and micronutrients important for bone health and can be consumed as part of a healthy diet.

See also:

• Eating yogurt linked with healthier bones and physical function over 60s
• Fermented milk products are linked with strong healthy bones 
• Dietary calcium is better for bone health
• Eat your way to stronger bones: fermented dairy products such as yogurt may help 

Sources:

• Sahni S, Tucker KL, Kiel DP, Quach L, Casey VA, Hannan MT. Milk and yogurt consumption are linked with higher bone mineral density but not with hip fracture: the Framingham Offspring Study. Arch Osteoporos. 2013;8: 119. doi:10.1007/s11657-013-0119-2

• Rizzoli R, Biver E. Effects of Fermented Milk Products on Bone. Calcif Tissue Int. 2018;102: 489–500. doi:10.1007/s00223-017-0317-9Laird E, Molloy AM, McNulty H, Ward M, McCarroll K, Hoey L, et al. Greater yogurt consumption is associated with increased bone mineral density and physical function in older adults. Osteoporos Int. 2017;28: 2409–2419. doi:10.1007/s00198-017-4049-5

• Les références nutritionnelles en vitamines et minéraux. In: Anses [Internet]. 23 Apr 2021

• Office of Dietary Supplements – Calcium.

• Melse-Boonstra A. Bioavailability of Micronutrients From Nutrient-Dense Whole Foods: Zooming in on Dairy, Vegetables, and Fruits. Frontiers in Nutrition. 2020;7.

• Uday S, Högler W. Nutritional rickets & osteomalacia: A practical approach to management. Indian J Med Res. 2020;152: 356–367.

• He M, Yang YX, Han H, et al. Effects of yogurt supplementation on the growth of preschool children in Beijing suburbs. Biomed Environ Sci. 2005;18:192–7.

• Laird E, Molloy AM, McNulty H, et al. Greater yogurt consumption is associated with increased bone mineral density and physical function in older adults. Osteoporos Int. 2017;28:2409–19.