Macronutrient and energy intakes in young children fed milk products containing different quantities and qualities of fat and protein

Protein intake in children and growth and risk of overweight or obesity: A systematic review and meta-analysis

Objectives

The aim of this study was to examine the evidence for an association between the dietary protein intake in children and the growth and risk of overweight or obesity up to 18 years of age in settings relevant for the Nordic countries.

Methods

We searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and Scopus up to February 26, 2021 for randomized controlled trials (RCTs) or prospective cohort studies assessing for protein intake from foods (total and from different sources) in children. The outcomes include weight, height/length, adiposity indices, and/or risk of overweight and/or obesity. The risk of bias was evaluated with instruments for each respective design (Cochrane's Risk of Bias 2.0 and RoB-NObS). A meta-analysis of five cohort studies was performed. The evidence was classified according to the criteria of the World Cancer Research Fund.

Results

The literature search resulted in 9,132 abstracts, of which 55 papers were identified as potentially relevant. In total, 21 studies from 27 publications were included, of which five were RCTs and 16 were cohort studies. The RCTs found generally null effects of high-protein intake in infants on weight gain, nor that lower protein diets negatively affected growth. All included RCTs had some concern regarding the risk of bias and were limited by small sample sizes. Total protein intake and BMI were assessed in 12 cohorts, of which 11 found positive associations. The meta-analysis revealed a pooled effect estimate of 0.06 (95% CI 0.03, 0.1) kg/m2 BMI per one E% increment in total protein (I 2 = 15.5). Therefore, the evidence for a positive relationship between total protein intake and BMI was considered probable. Furthermore, there was probable evidence for an association between higher intake of animal protein and increased BMI. There was limited, suggestive evidence for an effect of total protein intake and higher risk of overweight and/or obesity, while no conclusions could be made on the associations between animal vs. plant protein intake and risk of overweight and/or obesity.

Discussion

In healthy, well-nourished children of Western populations, there is probably a causal relationship between a high-protein intake in early childhood (≤ 18 months) - particularly protein of animal origin - and higher BMI later in childhood, with consistent findings across cohort studies. A lack of RCTs precluded a stronger grading of the evidence.

No differences in growth or body composition from age 12 to 24 months between toddlers consuming 2% milk and toddlers consuming whole milk

OBJECTIVE

To determine whether consumption of 2% milk during the second year of life leads to reduced growth or lower percentage body fat compared with consumption of whole milk.

SUBJECTS

Subjects were healthy toddlers who participated in a larger trial examining the effects of the timing of introduction of solid foods on growth.

DESIGN

Three-day diet diaries, anthropometric measurements, and body composition determined by dual-energy x-ray absorptiometry were assessed at 12, 18, and 24 months of age. At age 12 months, the toddlers were similar in length, weight, percentage body fat, and total energy intake. From 12 to 24 months of age, milk consumption consisted of whole milk exclusively in one group (n = 23) and 2% milk exclusively in another group (n = 28).

STATISTICAL ANALYSES

Differences between the 2 groups in anthropometric measurements, changes in anthropometric measurements, and dietary intakes were determined by Student t tests. Mean differences were considered significant at the P = .05 level. Data are presented as mean +/- standard deviation.

RESULTS

Despite lower intakes of total fat and saturated fat in the 2% milk group, there were no differences in height, weight, and percentage body fat. Total energy intake was not reduced in the 2% milk group.

APPLICATIONS

Reductions in total fat and saturated fat intake in toddlers can be achieved through the use of 2% milk without compromising growth.

Fatty acid content of plasma lipid fractions, blood lipids, and apolipoproteins in children fed milk products containing different quantity and quality of fat

BACKGROUND

Differences in fatty acid content of plasma lipid fractions and serum lipid concentrations were investigated among young children fed different milk diets composed to achieve a recommended saturated fat intake.

METHODS

Thirty-eight healthy children were randomly assigned to one of four feeding groups at 12 months: 1) low-fat milk (1.0 g/dL cow's milk fat); 2) standard-fat milk (3.5 g/dL cow's milk fat); 3) partially vegetable fat milk (3.5 gtat/dL fat; 50% vegetable fat: rapeseed oil); and 4) full vegetable-fat milk (3.5 gtat/dL fat; 100% vegetable fat: palm, coconut, and soy oil). Plasma fatty acids, blood lipids, and apolipoproteins were analyzed at 15 months, and dietary intakes at 12, 15, and 18 months.

RESULTS

There were significantly lower percentage contributions of saturated fatty acids in plasma triglycerides in children fed low-fat milk or milk with 50% or 100% vegetable fat than in children fed standard-fat milk. Plasma polyunsaturated fatty acid levels were significantly higher in children fed milks with vegetable fat than in children fed standard-fat milk. Plasma saturated and polyunsaturated fatty acids in triglycerides most closely reflected dietary intake. Blood lipid concentrations were lower in children fed milk with 50% vegetable fat.

CONCLUSIONS

Children fed milk with 50% or 100% vegetable fat, together with high vegetable-fat and low milk-fat dairy products have lower percentages of plasma saturated fatty acids and higher percentages of polyunsaturated fatty acids than children fed standard- or low-fat milk and dairy products.