Overview
Calcium is one of the most plentiful minerals in our body. 90% is contained in bones and teeth and another 10% in other tissues. The main role of calcium in our body is
- Bone and teeth composition
- Blood clotting
- Muscle contraction and relaxation (including heart muscle)
- Transmitting signals between neurons and muscles
- Normal functioning of many enzymes
Body precisely controls blood calcium levels. When blood calcium level is low, the body moves out calcium from bones. When people don’t consume normal amounts of calcium, it can weaken teeth and bones, causing osteoporosis. Bones become more fragile and prone to fractures. Children with low calcium intake may have growth problems and skeletal deformities (rickets).
Daily needs
Daily calcium needs vary for different groups. Children, adolescents, and people over age 50 are at risk of getting low calcium levels (hypocalcemia).
Daily calcium requirements are listed below.
- 0–6 months: 200 milligrams (mg)
- 7–12 months: 260 mg
- 1–3 years: 700 mg
- 4–8 years: 1,000 mg
- 9–18 years: 1,300 mg
- 19–50 years: 1,000 mg
- 51–70 years: 1,000 mg for males and 1,200 mg for females
- 71 years and above: 1,200 mg
- Pregnant and breastfeeding women: 1,000–1,300 mg depending on age
Doctors may recommend additional calcium for people who have started menopause, stop menstruating due to anorexia nervosa or excessive exercise, have lactose intolerance or a cow’s milk allergy, or follow a vegan diet.
- People with underlying gastrointestinal disease could have problems with micronutrient absorption. They may require more than 1200 mg of calcium per day.
The recommended upper limit of calcium intake is 2500 mg for adults 19-50. For those 51 and older, the upper limit is 2000 mg.
Dietary sources
The primary dietary sources of calcium are dairy products and milk. The following are good sources:
- Yogurt
- Fortified dairy alternatives, such as soy milk
- Cheese
- Sardines and salmone
- Tofu
- Green leafy vegetables, such as broccoli, kale, turnip leaves, watercress
- Fortified breakfast cereals
- Fortified juices
- Nuts and seeds, especially almonds, chia, and sesame seeds
- Legumes and grains
- Cornmeal and corn tortillas
- Some greens, such as spinach, contain calcium. However, they contain certain acids that lower calcium absorption.
Vitamin D
Vitamin D is essential for calcium absorption. Without adequate vitamin D levels, only 10% of dietary calcium is absorbed. With sufficient blood vitamin D level, absorption increases to 30-40%. Our body makes vitamin D when exposed to the sun. But too much sun can cause skin problems, including skin cancer.
Calcium supplements
It’s always better to get calcium from dietary sources, but if you’re not getting enough calcium from your food, doctors may recommend calcium supplements.
Calcium supplements come in different forms and doses. They contain different amounts of calcium, referred to as elemental calcium. Common forms of supplements are:
- Calcium carbonate (40% elemental calcium)
- Calcium citrate (21% elemental calcium)
- Calcium gluconate (9% elemental calcium)
- Calcium lactate (13% elemental calcium)
- Calcium carbonate is the most affordable one. It’s a good first choice. Absorption of calcium carbonate could decrease in people who take medicines that lower gastric acidity. Calcium citrate is well absorbed both during and after mealtimes and is a good choice for people with low gastric acidity.
Calcium supplements are available in a variety of forms, including tablets, capsules, chews, liquids, and powders.
Talk with your GP about choosing the best form, dose, and regimen of calcium supplements.
Some supplements are combined with vitamin D for better absorption.
Taking in small doses (500 mg or less) at mealtimes also increases the absorption.
People should avoid drinking caffeinated coffee and eating high-salted food because they lower calcium absorption.
Interactions with other medications
Before taking calcium supplements, talk with your GP to review any possible interactions of calcium supplements and other medications that you take. Calcium supplements can interact with many different prescription medications, including blood pressure medications, synthetic thyroid hormones, bisphosphonates, antibiotics and calcium channel blockers.
Side effects of calcium supplements
Usually they have a few side effects:
- Constipation
- Indigestion
- Bloating
- Kidney stones
There is no evidence that high dietary calcium intake increases the risk of getting kidney stones. However, use of calcium supplements may increase the risk in susceptible individuals, by increasing urine calcium levels. That’s why calcium supplements should be taken during meals and daytime. Tell your doctor if you’re taking calcium supplements, because high blood calcium could damage your health.
