Protein and Immunonutrients: Shaping the Health of Mother and Child

Protein sources and quality

A high-quality protein is easily digestible and supplies all the essential amino acids required for growth, repair, and maintenance.¹ Plant-based foods like nuts, grains, legumes, etc. are largely considered as primary protein sources, but may lack few of the essential amino acids.¹ However, appropriate combinations of vegetarian sources can ensure that complete protein is achieved by complementation of amino acids. Animal sources of protein like milk and milk products, fish, eggs etc. are considered complete sources, with all the essential amino acids. Altogether, these protein sources should be optimized to meet body’s entire amino acid requirements during pregnancy.^1,4

Protein turnover during pregnancy

Evidence suggests that the protein turnover in the first trimester is almost similar in pregnant and non-pregnant women. In contrast, protein synthesis increases by 15% and 25% in the second and third trimesters, respectively.¹ These changes in protein metabolism occur to meet increased fetal demands, maintain maternal homeostasis, and prepare for lactation phase.¹

Protein quality in Indian traditional diet

A post-hoc analysis of results of a survey by National Nutrition Monitoring Bureau (NNMB) of India revealed following facts for the quality of protein consumed by pregnant women in India.⁴

• A pooled, diet protein inadequacy risk of 76.9% was reported for corrected digestible indispensable amino acid (DIAA) requirements for Indian pregnant women.
• An inverse relationship between DIAA score for pregnancy diet and prevalence of LBW in India.

Thus, the review highlighted the need of improvement in protein adequacy of Indian diet for pregnant women. Table 1 represents the latest recommended daily allowance (RDA) for protein in pregnant and lactating mothers.

Table 1: Protein requirements during pregnancy, lactation, and infancy³(Adapted NIN Report, 2020)

Impact of mother’s diet on fetal development

The composition of the mother’s diet and birth outcomes are associated with each other. Thus, maternal nutritional status impacts fetal body weight and proportion. ^3,5 A few observational studies showed that maternal protein intake was associated with increased birth weight independent of energy intake, body mass index (BMI), maternal age, or lifestyle-related factors. The protein intake of 10-25% of the total energy may be safe.¹

• Higher protein intake is linked with increased birth weight and ponderal index⁵
• The consumption of a higher amount of energy from the protein in the initial stages of pregnancy was significantly and positively associated with 16 g increase in birth weight (95% confidence interval [CI]; borderline values: 2.8 to 29.2 g) and 4.2 g increase in placental weight (95% CI; borderline values: –0.4 to 8.5 g) for every 1% increase of protein in the diet. This correlation was independent of maternal age, parity, and smoking.
• The intake of energy from dairy protein was favorably linked with birth weight and improved ponderal index. A 0.12 kg/m³ increase in the ponderal index and a 24 g increase in birth weight was observed for every 1% increase in dairy protein intake.

Multiple micronutrient deficiencies may present during pregnancy and lactation, which may contribute to poor pregnancy outcomes, infant growth and weak immune system of the mother.⁵ The most prominent cause of micronutrient deficiencies is a poor-quality diet.⁷ Table 2 presents the latest National Institute of Nutrition (NIN) experts recommended daily allowance (RDA) of essential immunonutrients and their role during pregnancy and lactation.

Table 2: Role and RDA of immunonutrients during pregnancy and lactation^{3, 8-11}

RDA: recommended daily allowance; AI: adequate intake; NK: natural killer; RNS: reactive nitrogen species;
ROS: reactive oxygen species; Th: helper T cell

Women are commonly vulnerable to micro- and macro-undernutrition during their pregnancy and lactation period due to increased food and nutrient requirements.¹² Evidence suggests that nutritional deficiencies are present in all segment of the populations and continues throughout the lifetime of a women.¹² WHO recommends adequate energy/protein intake in pregnant women to meet pre-pregnancy BMI and individualized gestational weight gain.¹ Therefore, a review of NNMB survey from India recommended optimising the diet of Indian pregnant women for its protein quality.⁴ Another study recommended a balanced protein intake through supplements in women, who are at risk of protein deficits to improve pregnancy outcomes.¹³

A Cochrane Review of 12 randomized controlled trials (n=6705) reported that protein-energy supplementation in pregnant women increased birth weight and even decreased risk of small-for-gestational-age (SGA) infants and stillbirth. ¹

Like macronutrients, micronutrients too play a critical role in cellular signalling and functioning, reproductive health, work capacity, learning, and cognitive function, as well as in the evolution of microbial virulence.¹⁴ Various micronutrients such as vitamin C, riboflavin zinc, iron, etc. have immune-modulating functions; thus, affect the susceptibility to infectious diseases. The antioxidant function of some micronutrients regulates immune homeostasis.¹⁴ Therefore, micronutrient supplementation is preferred to prevent and manage micronutrient deficiencies in such populations.¹⁴

A woman’s health affects socio-economic aspects of the family.¹⁴ The importance of a balanced and healthy diet before and during pregnancy and lactation should not be undermined.¹ Evidence suggests that the risk of protein inadequate diet among Indian pregnant women is significantly high and associated with prevalence of LBW.⁴ Therefore, nutritional supplementation is critical in meeting the recommended dietary intake of protein and immune nutrients in women.¹⁴
On this ‘Mother’s Day 2021’, let us join hands to nourish motherhood!