In a number of scientific studies done fifteen years ago it was stated that an increased protein intake would adversely affect bone health as a result of an increased calcium content in the urine and a reduced calcium supply in the bones. New scientific findings do not endorse this effect.
According to the underlying theory of acid balance, proteins in the diet as well as phosphates increase the acidity of the blood. As a result of a slightly lower acidity (in more acidic blood) calcium is drawn from the bones as the body attempts to neutralise the blood.
No effect on the calcium balance
Although a higher protein intake does lead to a higher acid level in the urine and more calcium excretion via the urine, this has no effect on the overall calcium balance in the body, i.e. the difference between the dietary intake of calcium and excretion of this via urine and faeces. With a higher protein intake the body absorbs more calcium from food. Similarly, an increased phosphates content does not have any effect on the calcium balance.
A diet with sufficient protein helps preserve the bones. Based on overall scientific research, the scientific panel of the European Food Safety Authority (EFSA) concluded that there is a cause and effect relationship between the intake of protein, phosphorus and calcium, and maintenance of the bone mass. Only a very high protein intake combined with a low calcium intake could possibly have an adverse effect on the bone health. However, this very rarely occurs when dairy is included in a diet. Additionally, it is known that a high intake of caffeine, carbonated drinks, alcohol and salt may adversely affect the calcium balance.
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