Campbell said he grew up on a dairy farm and for a long time held to the belief that animal protein was an essential part of a healthy diet.

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The molecules of this protein are more or less globular, and are held in that shape by internal cross-links between different parts of the amino-acid chain of which the protein is composed.

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While Schwab kept looking for his protein, researchers identified other molecules that held up nerve growth.

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Kos has licensed its own version of the protein, reverse D-4F, from privately held Triad Pharmaceuticals .

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Carbohydrates were held steady at about 41% to 42% of calories while fat levels varied with the protein regimen.

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