Millets (defined broadly to include sorghum) are traditional staple foods, and climate smart nutritious crops, which are grown across Africa and Asia, they have not been mainstreamed globally like rice, wheat, and maize. Diversifying staples with millets can potentially provide more macro and micro nutrients, compared to the mainstream staples that are also often refined. However, there had been little known scientific evidence to prove millets’ efficacy on growth.
Nutrient requirements vary by age. During adolescence, typically the weight doubles and height increases 20% in healthy individuals [12][34]. During this time all the essential nutrients are required, especially protein, calcium, iron, and vitamins, to support bone accretion and to enhance the growth. Protein, especially branched chain amino acid leucine and sulphur containing amino acids, is a key nutrient required to support the development of muscle mass, and therefore, are especially important during adolescence [12][34]. Calcium always remains as a priority nutrient for bone growth especially during the tremendous growth periods of infancy (first twelve months) and adolescents (13 to 18 years).
Finger millets have a threefold higher concentration of calcium than milk, and calcium retention is higher for finger millet than for any other staple [13][15]. Moreover, millets contain more methionine, sulphur amino acids, compared to milled rice and refined wheat [7]. In the regular diets, there was a significant positive effect of replacing rice with millet on height, weight, MUAC, and chest circumference in various age groups (infant, pre-school, school going, and adolescents). These positive effects of millets are attributed to the naturally high content of growth promoting nutrients (especially sulphur amino acids, total protein, and calcium in case of finger millets), given that the rest of the diet was similar between the two groups. Table 13 has information [14][15][27,28] on food provided in the interventions with preschool and school-going children, showing the composition of the diets based on diversified and enhanced rice and diversified and enhanced finger millet, compared to regular rice-based diets. It is noted that the enhanced diets based on finger millet had higher quantities of each food group: with 45% more finger millet, 270% more pulse, 59% more dairy products, 140% more green leafy vegetables, and 64% more fruits. On the other hand, the enhanced rice-based diets had higher quantities of each food group: 35% more rice, 327% more pulse, 59% more dairy products, 194% more green leafy vegetables, and 70% more fruits, compared to the regular rice-based diets. This likely explains the reason for the significant growth observed in the groups fed with the enhanced finger millet and enhanced rice-based diets, compared to the controlled regular rice-based diet group. On the other hand, there was no significant difference between the enhanced finger millet and enhanced rice diets in terms of consumption quantity per day, i.e., they were similar diets, with the main exception being a substitution of rice with millet. There was no significant difference between enhanced finger millet and enhanced rice-based diets in any of their growth parameters except chest circumference, which received a slight increase in growth (2%) in the enhanced finger millet-consuming group.Food Items (g/day) | Enhanced Finger Millet Based Diet | Enhanced Rice Based Diet | Control Diet (Regular Rice Based Diet) |
---|---|---|---|
Mean ± SD | Mean ± SD | Mean ± SD | |
Millet/rice (g) | 245 ± 20.4 | 228.3 ± 26.3 | 168.7 ± 26.2 |
Pulses (g) | 100 ± 8.6 | 115.3 ± 5.0 | 27.0 ± 11.2 |
Milk & milk products (g) | 54.2 ± 6.7 | 54.0 ± 9.6 | 34.0 ± 6.4 |
Roots and tubers (g) | 96.7 ± 25.7 | 113 ± 37.2 | 57.2 ± 9.3 |
Green leafy vegetables (g) | 39.2 ± 6.1 | 47.6 ± 4.9 | 16.2 ± 4.7 |
Oils and fats (g) | 8.5 ± 1.7 | 8.6 ± 2.3 | 6.5 ± 1.0 |
Sugar (g) | 10 ± 0.0 | 10.6 ± 1.2 | 6.5 ± 1.7 |
Nuts (g) | 51.9 ± 2.1 | 53.0 ± 5.6 | - |
Fruits (g) | 8.7 ± 0.5 | 9 ± 0.0 | 5.3 ± 0.5 |
This shows, that when the diet is enhanced, diverse, and nutritious, there is only minimal extra growth achieved from consumption of millet-based diets compared with rice-based diet. This is a reasonable result given that the control diet contains a diverse range and adequate quantities of nutritious foods. However, when the base diet was not enhanced and had lower nutritional value, substituting rice with millet had a large and significant impact on additional growth [6][16][17][6,32,33]. This provides evidence that including millets as the staple in malnourished communities can significantly improve the health and hence growth of the people.
All major growth promoters should be measured in future studies. Methionine is an essential sulphur containing amino acid and a major growth promoter. Apart from methionine, total protein, calcium, and zinc are essential as growth promoters, which were also not measured. Growth impacts of the different types of cooking/processing of the millets should be analysed to inform more detailed recommendations for dietary design. Only one study was designed to analyse the impacts of millet-based diets on children’s growth during adolescence, the third critical stage of rapid growth and bone mineralization in human life, which calls for further studies. 9. Except two studies, all other studies were conducted in the 1980s by one research team, suggesting that new studies should be undertaken to corroborate the results.