A review on protein intake in Nigeria by de Vries-ten Have et al was published in Nutrition Research Reviews recently. It examined the Nigerian diet and protein intake in infants, children, adolescents, and pregnant and lactating women. In this article, FrieslandCampina Institute interviews the principal investigator, Judith de Vries-ten Have on the findings.
Can you introduce the Nigerian diet?
Within our study we reviewed available literature that assessed the composition of the Nigerian diet. We found that staple foods made up a large proportion of the Nigerian diet. Cereals such as wheat and rice, and roots and tubers such as yam and cassava are eaten by a large percentage of the population. Beans and groundnuts are frequently eaten legumes. The consumption of animal foods such as beef, chicken and fish varied per geographical region. Dairy products were not widely consumed.
Overall, the Nigerian diet consists mainly of cereals and other plant-based foods, with animal-source foods being consumed to a lesser extent. Eating a diverse diet, with both plant-based and animal-based products, increases the chance of meeting nutrient requirements. Resource-poor settings are often characterized by consuming monotonous diets, increasing the risk for nutrient inadequacies.
Why was protein the focus in this review?
Protein-energy malnutrition (PEM) is widely present in developing countries including Nigeria. PEM can result in acute and chronic malnutrition, especially wasting and stunting. Adequate protein intake is especially important for infants, children and adolescents. These life stages are characterised by rapid increases in height, weight, development and function maturation, which require higher protein intake. Pregnant and lactating women also have increased protein intake demands, for net tissue deposit or milk formation.
In Nigeria, low cost foods rich in good quality protein are scant. This makes it difficult to meet protein and amino acid requirements. Therefore, our paper examined protein intake adequacy, both in terms of quantity and quality. One can have an adequate protein intake when you look at total grams, but the quality of these proteins may not be good enough. Protein quality was measured using the Digestible Indispensable Amino Acid Score (DIAAS), which, in short, examines if a protein contains sufficient essential amino acids (EAA) to meet the requirements. The amount of EAA that protein provides is very important because our body cannot make EAA and they need to come from dietary sources. All 9 EAA in sufficient quantities are required in sufficient quantities to support optimal growth and health.
The review compared the dietary intake of protein of several population groups (infants, children, adolescents, and pregnant and lactating women) with the recommended daily intakes. Tell us about the findings.
Most data available on protein intake (quantity) were obtained from southern Nigeria (economically richer). Thus, the review findings might not fully reflect the whole country’s protein adequacy as the population in the poorer north might not have the purchasing power to acquire protein-rich foods. In southern Nigeria, protein intakes were mostly adequate for children and non-pregnant and non-lactating women, compared with the recommended daily intakes.
Conversely, the protein intake of adolescent girls was mostly inadequate. Pregnant and lactating women were also eating insufficient quantities of protein. This is of particular concern, because inadequate protein intake during pregnancy has short- and long-term negative consequences for both the infant and mother. Adequate nutrition is important during the pregnancy and lactation period, as the nutritional content of breast milk and thus the fetal development is dependent on maternal diet.
What can be done to bridge the gaps in protein quality and quantity in the Nigerian diet?
We determined the protein quality of 9 commonly eaten foods that constituted the Nigerian diet: wheat, rice, maize, yam, cassava, cowpea, sorghum, fish and groundnut. We found that the protein quality of all plant-based foods was poor. The most limiting amino acid was lysine. Fish was an excellent source of protein. From literature we know that milk, eggs, beef, chicken and soya beans are also excellent sources of protein.
To demonstrate how addition of a high quality protein to the staple food would improve the diet, we examined an example of a mixture of commonly eaten plant and animal based foods: rice, cowpeas and fish. This mixture was shown to be a source of good quality protein.
The addition of small amounts of animal-based proteins such as milk, cheese, eggs and meat or soya can bridge the protein quality gap that is created by a predominantly plant based diet. For example, milk could be a valuable addition to the Nigerian diet, especially for malnourished children. Plant based foods can make a valuable contribution to overall protein intake, with cereals such as rice and wheat providing adequate amounts of most of the EAA apart from lysine
Future steps include determination of protein quality of more foods and mixtures, and developing and promoting good quality protein rich products or meals that are cost-effective.