Did you know that osteoporosis is now considered a pediatric disease? Did you ever suspect that soft drinks were unhealthy for you or your kids, but had no hard data to back it up? Well, now you do!
In this study eighteen kids aged 13-18 years, drank either a caffeine and sugar free soft drink, or a soft drink with caffeine or sugar sugar. When caffeine was added, three hour urinary calcium excretion increased by 25% (from 6 mg to 20 mg per hour). When sugar was added to the caffeine drink, urinary calcium loss almost doubled (from 16 mg to 30 mg per hour). They found that sodium, chloride and potassium loss were also increased by caffeine.
Phosphorus, found in most cola drinks, accelerates calcium and bone loss even more. Colas with caffeine and sugar added cause the greatest calcium and bone loss.
Comment: Everyone recognizes the importance of calcium in the diet of young people ( and older too). What this study tells us is that, while it is important to have adequate calcium in our diets, it is just as important not to overeat foods that cause calcium loss. The combination of caffeine and sugar almost doubles calcium lost through the urine. . The experimental dose used in this study was far less than the average teen's daily consumption of caffeine and sugar. After a hard physical workout, drinking soft drinks can cause calcium and potassium loss, and that in turn can cause sore muscles and delayed recovery time after exercise.
Other foods that cause calcium loss are foods rich in phosphorus, including cola soft drinks. High protein diets can cause bone loss also.
Non-dairy high calcium foods include the dark leafy greens (Collards 360 mg/cup, kale 210 mg/cup, broccoli 160 mg/cup), tofu, navy, and pinto beans (100-150 mg/4 oz), black strap molasses (140 mg/Tbs), corn tortillas (120 mg/2) and whole grains, sardines, salmon, goat feta cheese.
Massey, l.k. Acute effects of dietary caffeine and sucrose on urinary mineral excretion in healthy adolescents. Nutr. Res 8(9): 1988