The Institute of Nutrition of Central America and Panama in Guatemala conducted a comparative study between the protein in amaranth and cheese protein.  Researchers concluded that the protein in amaranth is among the most nutritious vegetable-based protein and can be considered on par with protein from animal-based products.
Plant Foods for Human Nutrition, March 1993; 43(2):123-43

A study from Oregon Health Services University examined the impact that a transition to a more ‘affluent’ diet had on thirteen Tarahumara Indians (five women and eight men).  Tarahumara Indians are a Mexican people traditionally consuming a low-fat, high-fiber diet and with very low incidence of risk factors for cardiovascular disease.  The thirteen subjects were fed their traditional diet (2700 kcal per day) for one week and were then fed a diet typical of affluent societies, which contained excessive calories (4100 kcal per day), total fat, saturated fat, and cholesterol for five weeks.  After five weeks of consuming the affluent diet, the subjects’ mean cholesterol levels increased by 31%, and plasma triglyceride levels also increased by 18%.
New England Journal of Medicine 1991 Dec 12;325(24):1704-8. (McMurry et al.)

In an experiment at the University of Alberta, barley kernels were sprouted from 2 to 5 days, then oven-dried and milled. Researchers found decreases in dry matter, gross energy (calories) and triglycerides, and increases in fiber and diglyceride content. After the sprouted barley was fed to rats, scientists said that “digestibility data showed an enhancement of digestibility of nutrients in barley… implying that sprouting improved nutritional qualify of barley.”
Plant Foods for Human Nutrition, September 1989; 39(3):267-78.

In a 1989 meta-analysis of existing studies, JK Chavan and SS Kadam found evidence that “Sprouting of grains for a limited period causes increased activities of hydrolytic enzymes, improvement in the contents of certain essential amino acids, total sugars, and B-group vitamins, and a decrease in dry matter, starch, and antinutrients. The digestibilities of storage proteins and starch are improved due to their partial hydrolysis during sprouting.”
Critical Reviews in Food Science and Nutrition, 1989; 28(5):401-37.

Researchers in Peru fed toasted amaranth flour, popped amaranth grain, and amaranth flakes to young children as the source of all dietary protein and fat, and as 50% of their daily energy requirements.  Later, children were fed a mix of amaranth and corn in various flour, flake, and meal forms.  Results showed that protein uptake from amaranth flour was favorable, and combining amaranth with corn provided for better protein uptake than consuming corn alone.
The Journal of Nutrition, January 1988; 118(1):78-85