I have just been reading this paper “The Critical Role Played by Animal Source Foods in Human (Homo) Evolution” and I was interested in what it has to say about nutrition for children:
Another important aspect of Animal Source Foods (ASF) in the diet of human ancestors concerns the increasing importance, as human evolution progressed, of high quality, volumetrically concentrated foods for small children. The brain currently makes up 17% of a newborn human infant’s weight and 75% of the weight of the four major organs combined (brain, liver, heart, kidney). During the first year of life, while traditionally an infant is breastfed, the brain grows rapidly, after which its growth rate decreases. Eighty-seven percent of basal metabolic rate (BMR) in a 3.5kg newborn is due to energetic demands of the brain alone. By 5y of age, this figure has decreased to 44% and by adulthood, it is 23%. Thus, by age 5y, human brain weight is near adult size but body weight is only one-third of adult size.
A small child has to take in enough energy each day to fuel an almost-adult–sized brain, as well as meet high nutritional and other energetic requirements. In our evolutionary past, breast milk was the major food source for very young infants, and likely continued to be an important food for children up to the age of ≥4y.
But supplementary foods are needed after ∼6 months of age, and these must be compatible with a glucose-demanding, unusually large brain, a gut size that scales to body mass, energetic requirements that scale to the three-fourth power, a slow rate of food turnover, and a high demand for energy and nutrients by the growing and active young child.
Because of the increase in the ratio of metabolic requirements to gut capacity in homeotherms, a diet high in fibrous plant material could pose virtually insurmountable problems for small children. Meat, organs, brains, viscera and marrow are highly digestible, concentrated sources of iron, calcium, iodine, sodium and zinc as well as vitamins A, B-1, niacin, B-6, B-12, folate, vitamin K and other micronutrients, as well as high quality protein and essential fatty acids.
If the dietary trajectory described above was characteristic of human ancestors, the routine, that is, daily, inclusion of ASF in the diets of children seems mandatory as most wild plant foods would not be capable of supplying the protein and micronutrients children require for optimal development and growth, nor could the gut of the child likely provide enough space, in combination with the slow food turnover rate characteristic of the human species, to secure adequate nutrition from wild plant foods alone. Wild plant foods, though somewhat higher in protein and some vitamins and minerals than their cultivated counterparts, are also high in fiber and other indigestible components and most would have to be consumed in very large quantity to meet the nutritional and energetic demands of a growing and active child.”
I weaned my son using the principles described in Sally Fallon’s book ‘The Nourishing Traditions Book of Baby & Child Care’ (you can find it in our Amazon Shop linked in above menu). This meant his first foods were egg yolk and then liver! Both easily digested and rich in energy and micronutrients.