Extremely impoverished diets fail to supply necessary elements for blood formation and lead to impaired health and usefulness.

Original passage

Another class, in their desire to set a right example, go to the opposite extreme. Some are unable to obtain the most desirable foods, and, instead of using such things as would best supply the lack, they adopt an impoverished diet. Their food does not supply the elements needed to make good blood. Their health suffers, their usefulness is impaired, and their example tells against, rather than in favor of, reform in diet.