Nutrition, Physical Activity & Bone Health
Adequate nutrient intake and physical activity are key factors in building strong bones and optimizing bone mass, which reduces the risk of osteoporosis. Osteoporosis is the most common bone disease in humans and is characterized by loss of bone mass, decreased bone strength, and increased risk for fracture.
While calcium is the most important nutrient for bone health, there are many other nutrients that can affect calcium status both positively and negatively.
Vitamin D: Plays a critical role in bone mineralization because it acts to maintain blood calcium and phosphorus levels. When the body is deficient in vitamin D, this results in insufficient calcium absorption. Calcium is then taken from the bone to maintain plasma calcium levels. Magnesium: Most magnesium is located in the bone so reduced intake may contribute to osteoporosis. Supplementation with magnesium has shown improvement in bone density. Phosphorus: Like calcium, most of the phosphorus in our bodies is found in the skeleton. If there is a change in phosphorus balance it is reflected in bone mass. Phosphorus deficiency is rare because it is high in typical diets, and the kidneys can produce phosphorus free urine in response to hypophosphatemia. Sodium and protein: High sodium and protein intake is associated with increased urinary excretion of calcium. Caffeine: one cup of coffee causes a loss of 2-3 mg of calcium.
Physical activity at a young age is important for many reasons, one of which is bone health. A 4-year study looked at bone mineral density in children aged 7 – 9 years. The intervention group participated in 40 minutes of physical education for each day of school (200 min/week), and the control group participated in 60 minutes per week. Even though the intervention group accumulated much more time of activity, there was no difference in the ratio for fractures. Compared to the control group, the intervention group had mean annual gains in lumbar spine bone mineral density was 7.0% higher in girls and 3.3% higher in boys, and in femoral neck width they had 1.7% higher in girls and 0.6% higher in boys.