Calcium makes bones strong.

Calcium is magnesium and iron, one of the most important minerals for humans. Largely thanks to the lobbying of the dairy industry, almost every child can associate calcium and strong bones with the consumption of dairy products. But milk is not the only good source of calcium, and in addition to growing and maintaining bones, calcium has other important functions.

Among other things, calcium plays an important role in the communication between the brain and the rest of the body, and in the function of muscles and the heart. For example, when a muscle receives a nerve impulse, the body releases calcium, which helps the proteins in the muscle contract. When the body removes calcium from the muscle, the muscle relaxes.

The importance of calcium for bone health

The first thing that is associated with calcium deficiency is bone thinning. Primary signs of calcium deficiency Symptoms may include muscle cramps, numbness in the hands and feet, or broken nails. The next signs are softening of the bones and thinning of the bone tissue, or osteoporosis.

Calcium really does play an important role in bone health. Bones are living tissue and therefore constantly changing. Throughout life, damaged bone tissue is constantly being broken down and new bone is being built. In healthy adults, the rate of building exceeds the rate of breaking down until around the age of 30. After that, bone growth slows down and bone loss begins. Bone loss tends to be greater and faster in women. Hormonal changes after menopause also play a role.

Several sources offer hope that increasing bone density through supplemental calcium intake during this time of rapid bone growth will provide some protection against bone loss and osteoporosis later in life. Unfortunately, clinical studies suggest that however, it has no long-term effect.

Studies of calcium intake and bone loss in menopausal women have yielded mixed results. This may be because some studies only looked at calcium from supplements and did not consider calcium from food, or did not take into account other factors, that affect calcium absorption, such as vitamin DNamely, calcium and vitamin D interact in the body. A sufficient amount of vitamin D increases the positive effects of additional calcium intake significantly on bone density.

Several large studies have shown that higher calcium intake, typically achieved with 500–1200 mg/d of calcium supplementation, increases bone density in menopausal women and reduces the risk of hip fracture.

The effect of calcium on blood pressure

Several review studies have suggested that calcium may have a blood pressure-lowering effect. Unfortunately, such studies often suffer from various problems, such as small numbers of participants, differences between subjects, and other confounding factors.

Blood pressure-lowering effect of calcium in people with normal blood pressure not yet confirmedHowever, it has been observed some systolic blood pressure-lowering effects of calcium people with high blood pressure and pregnant women.

Cardiovascular diseases and calcium

Some studies have raised concerns that calcium supplements may be harmful to heart health, increasing the risk of cardiovascular disease. It was thought that high doses of calcium and an excess of calcium could cause hypercalcemia, which in turn could lead to blood clotting or hardening of the arteries. However, no reliable link has been found between calcium and cardiovascular disease. However, it is important not to exceed the upper limit of calcium intake, which is 2,500 mg/day.

Rectal cancer and calcium

Epidemiological studies that follow people over long periods of time have suggested that Higher calcium intake may have some protective effect against rectal cancer. However, controlled studies have yielded mixed and contradictory results in this regard. The reason may be that clinical controlled studies are significantly shorter than epidemiological studies. Rectal cancer can take 7–10 years to develop. In the meantime, we will wait for new studies.

Kidney stones and calcium

In the past, calcium intake was associated with the formation of kidney stones, as one of the most common types of kidney stones is calcium oxalate stones. Researchers have studied this topic and found that a large foods high in calcium instead, they reduce the risk of kidney stones. With calcium supplement It didn't go so well - too much calcium in supplements is actually bad. Calcium supplements do indeed increase the risk of kidney stones.

Type 2 diabetes and calcium

Researchers have found that taking a calcium supplement with or without vitamin D lowers the risk of type 2 diabetesSo if you're not afraid of kidney stones and are at risk for type 2 diabetes, it might be worth trying a calcium supplement. However, you can increase your calcium intake without a supplement by eating more calcium-rich foods.

Calcium bioavailability

Unfortunately, the body doesn't produce calcium, so we have to get it from food. Fortunately, calcium is found in many foods. As with many other nutrients, not all sources are created equal. The total amount of calcium in a food may not reach the bloodstream at all. This is called bioavailability and is expressed as a percentage.

For example, milk contains about 120 mg of calcium per 100 g. The bioavailability of calcium in milk is about 30%, meaning that out of the 120 mg, our body absorbs about 40 mg of calcium. Plant-based sources of calcium, such as green leafy vegetables, contain less calcium than dairy products, but the bioavailability of the calcium in them is higher, about 40–60%. Calcium-fortified products, such as fortified soy milk, orange juice, and tofu, have similar bioavailability to milk.

Nutritional therapist Annely Soots writesthat “if we take into account the absorption rate of calcium in different foods and compare it to milk, instead of a glass of milk (240g) we would have to consume, for example,

• 40g Cheddar cheese,
• 150g calcium-enriched tofu,
• 300 g kale or broccoli,
• 1400g spinach,
• 700g pinto beans,
• 440g white beans,
• a glass of almonds,
• a glass of yogurt,
• a glass of calcium-fortified soy drink.”

Calcium from plants is prevented from being absorbed by oxalic and phytic acids. For example, spinach has about the same calcium content as milk, but the high oxalate content of spinach makes this calcium almost unavailable to us. The bioavailability of calcium in spinach is around 5%.

It should also be taken into account that calcium is absorbed in two ways: actively and passively. In the first case, using transporters and vitamin D, and in the second case, simply by absorption through the intestinal wall. In other words, for the active absorption of calcium, it is also important sufficient amount of vitamin DThis is especially important for people who lack calcium in their diet. Namely, in the case of a deficiency, calcium is mainly absorbed actively. If there is enough calcium in the diet, then vitamin D does not play such a big role in absorption.

Sources of calcium or foods containing calcium

Calcium is found in many foods, so if we eat enough and in a balanced way, we can easily get the necessary amount of calcium. Those who are on a dairy-free diet should especially analyze their menu with calcium in mind. It is recommended to do this analysis together with a competent with a nutritionist.

Calcium needs vary slightly by age. The recommended amount for those aged 10–30, pregnant women, and nursing mothers is 900 mg/day. For other adults, it is 800 mg/day.

Good sources of calcium according to the National Institute of Health database are:

• dried herbs (e.g. thyme, sage, oregano, marjoram, rosemary, coriander, cinnamon, etc.),
• seeds and nuts (poppy, sesame, chia and flax seeds, almonds, cashew and Brazil nuts),
• cheeses (parmesan, cheeses with a fat content of 10–15%, Emmental, Cheddar, white cheese),
• milk and yogurt,
• vegetables and leafy greens (nettle, leek, arugula, dandelion leaves, turnip tops, parsley, kale),
• dried rose hips and prunes,
• cereals (amaranth, oats, quinoa and rye),
• legumes (tofu, soy protein powder, carob flour, soybeans, tempeh, white beans).

If you exclude cheese and dairy products from the menu, it is especially important to eat a variety of calcium-rich foods from different food groups to get the necessary amount.