Calcium is an essential mineral for the body and should be consumed adequately. It has important functions in the body, helping to strengthen the structures of bones and teeth, preventing osteoporosis, involved in the contraction and relaxation of blood vessels, muscle and heart function, controlling blood pressure, preventing cramps, aiding blood clotting, nerve transmission, cell signaling, and hormone secretion.
What is Calcium
Calcium is the most abundant mineral in the body. 99% of calcium is in the bones and teeth. The rest is in the bloodstream and other tissues. The main function of calcium is maintaining bone strength and acting as a signaling molecule to cells and tissues throughout the body forblood vessels and muscles to contract and relax. It is also involved in blood clotting and nerve signaling.
The recommended daily intake of calcium for Thais according to age and gender per the 2020 Thai Recommended Daily Intake guidelines:
– Children ages 1-3 years: 500 mg/day
– Children ages 4-8 years: 800 mg/day
– Children and teens ages 9-18 years: 1,000 mg/day (During adolescence, 40% of adult bone mass develops, making this a crucial time to get adequate calcium)
– Adults ages 19-50 years: 800 mg/day (For women, decreased estrogen levels during menopause accelerate bone loss. Women have a higher risk of osteoporosis fractures than men since estrogen levels do not sharply decline in men. Bone loss occurs more gradually in men.)
– Adults and elderly over age 51: 1,000 mg/day (Should get adequate but not over 1,500 mg/day)
Dietary Sources of Calcium
Milk and dairy products from animals are the best sources of calcium, as they have high calcium levels and an optimal calcium-phosphorus ratio to promote calcium absorption. Other sources include small fish eaten whole with bones like plaice, herring, sardines; soy products like soft tofu and tempeh; leafy greens like Chinese kale, broccoli, amaranth; and winged beans.
Factors Inhibiting Calcium Absorption and Increasing Calcium Excretion
Foods high in sodium cause increased urinary calcium excretion like salty seasonings, processed meats, pickled foods. Food with baking powder, preservatives like baked goods, sausages, canned foods, instant meals.
Caffeine causes increased calcium excretion in urine and decreased absorption in the digestivetract from coffee, tea, energy drinks. Limit to 300 mg caffeine daily (2-3 cups of coffee). Studies show over this amount increases osteoporosis fracture risk by up to 20%.
Alcohol consumption of 2+ drinks daily for women and 3+ drinks daily for men increases risk of osteoporosis fractures because alcohol decreases intestinal absorption and increases urinary calcium excretion.
Substances that bind to calcium preventing full absorption like phytates (grains, nuts, seeds), oxalates (spinach, betel nuts, eggplant, cocoa), and tannins (tea, betel nuts, unripe bananas).
Smoking exposes the body to nicotine which inhibits calcium absorption.
Factors Promoting Calcium Absorption
Vitamin D improves calcium absorption in the small intestine. Main sources are sunlight exposure to UVB rays (9am-3pm). Smaller dietary sources include salmon, mackerel, egg yolks, cod liver oil, mushrooms.
Adequate protein intake stimulates gastric acid secretion which improves calcium absorption.
Foods to Avoid Taking Calcium With
1. Antibiotics like fluoroquinolones and tetracyclines as absorption is reduced. Take calcium supplements 2+ hours apart.
2. Some blood pressure medications like calcium channel blockers.
3. Thyroid hormone replacement drugs.
4. Bisphosphonate drugs.
Those on long-term medications should consult a doctor before taking calcium supplements.
Common Side Effects of Calcium Supplements
1. Constipation, gas, bloating. Constipation more often seen with calcium carbonate.
2. Consequences of excessive calcium intake?
3. Impairs iron and zinc absorption.
Excess calcium intake can lead to high calcium excretion in urine (hypercalciuria) which increases kidney stone risk. Do not exceed 2,000 mg daily.
Those with chronic kidney disease or impaired kidney function may already have high blood calcium and phosphate. Giving extra calcium to this group could increase risk of soft tissue calcification or calcification in blood vessels.
Choosing a Calcium Supplement
The actual elemental calcium varies by type of calcium salt. Calcium carbonate contains 40% elemental calcium. Calcium acetate 25%. Calcium citrate 21%. Calcium lactate 13%. Calcium gluconate 9%. For example, 1,000 mg calcium carbonate contains 400 mg elemental calcium.
The dosage per serving matters since there is an upper limit to how much calcium can be absorbed at once. Do not exceed 500 mg elemental calcium per dose.
Calcium is an essential nutrient that should be consumed at appropriate levels for age. Also avoid factors that impair absorption and increase excretion. Promote factors that enhance absorption so the body fully utilizes calcium to build strong bones
