Calcium is an essential mineral for the formation and preservation of bones and teeth (in association with zinc, magnesium, and certain B-group vitamins). It also plays a crucial role in muscle contraction, notably the contraction of the heart (heartbeat), nerve transmission (neurotransmission), blood clotting, energy metabolism, regulation of blood pressure, activation of certain enzymes (especially digestive ones), or even in hormonal secretion and the transport of certain amino acids.
Recommended Nutritional Intakes (per day)
Children: 600 to 800 mg - Adolescents: 1200 mg - Adults: 900 mg - Pregnant and breastfeeding women: 1000 mg - Women after 45 years: 1200 mg - Men after 55 years: 1200 mg.
Some voices argue that the Recommended Dietary Allowances (RDAs) for calcium are overestimated, especially in adults. Indeed, it might be more effective to increase the RDAs for vitamin D, magnesium, and zinc, which strengthen calcium's action in certain mechanisms, particularly for bone formation and consolidation.
Natural Sources of Calcium
Dairy products are not the only sources of calcium. Calcium is available in cruciferous vegetables (cabbage, broccoli, Chinese cabbage), fresh vegetables, fruits, almonds, walnuts, hazelnuts, mineral waters, and fish. Cruciferous vegetables offer the best calcium bioavailability, meaning that the calcium contained in cruciferous vegetables is better absorbed by the body compared to dairy products.
Calcium Sources per 100 g: green cabbage: 210 mg, Chinese cabbage: 280 mg, milk: 120 mg, almonds: 250 mg, sardines (with bones): 330 mg, watercress: 180 mg, dried figs: 190 mg, mineral water like Contrex (per 250 ml glass): 120 mg.
Increased Calcium Needs
Pregnancy, growth, fractures, prevention of osteoporosis starting from perimenopause in women and a little later in men.