All about fruitarianism with a long-term fruitarian, Lena

One study found that 0.85 mg of calcium was lost for each gram (1 g) of protein in the diet. A meta-analysis of 16 studies in 154 adult humans on protein intakes up to 200 g found that 1.2 mg of calcium was lost in the urine for every 1g rise in dietary protein. A small but more focussed study showed a rise of 40 mg in urinary calcium when dietary animal protein was raised from 40 to 80 g. Urinary calcium to dietary protein ratio is 1 mg to 1g. The empirical observation that each 1 g of protein results in 1 mg of calcium in the urine agrees very well with the phosphorus content of animal protein (about 1 percent by weight).

This means that a 40 g reduction in animal protein intake from 60 to 20 g would reduce calcium requirement by the same amount as a 2.3 g reduction in dietary sodium, i.e. from 840 to 600 mg

How animal protein exerts its effect on calcium excretion is not fully understood. 

Charles Darwin

There is no fundamental difference between man and the higher animals in their mental faculties . . . The lower animals, like man, manifestly feel pleasure and pain, happiness, and misery.

Nitrogen Balance

Nitrogen balance is a measure of nitrogen input minus nitrogen output

Nitrogen Balance = Nitrogen intake - Nitrogen loss

Nitrogen is a fundamental component of amino acids, which are the molecular building blocks of protein. Measuring nitrogen inputs and losses can be used to study protein metabolism. Apple