Nutrient supplements alone will not make children smarter Premium

Can poor nutrition result in poor cognitive development and lower adult IQ?

There are many holy grails for parents with respect to their children’s development and accomplishments, but the holiest must be their growing into adults with high Intelligent Quotient (IQ) and earning capacity. IQ, in turn, is tied closely to cognitive development, or the increasing ability of the growing child to think and reason.

Growth faltering, as an easily measurable outcome of poor nutrition, was shown in many cross-sectional studies to be associated with poor cognitive development. However, this was not simple and was confounded by poverty. The question was: did poor nutrition result in poor cognitive development and lower adult IQ? Some scholars naively linked stunting, as an indicator of poor nutrition, to poor cognitive development and a diminution of the child’s eventual adult capital, an intangible human asset linked to their knowledge, talents, skills, and abilities, among other qualities.

However, this single-cause interpretation lacked consideration of important mediators like schooling and its quality, which varies substantially with wealth and the home environment. A second interpretation was that if an early, nutritionally induced cognitive decline occurred, it would ‘track’ like a scar into adulthood, leaving its negative stigmata on the individual’s capital, and indeed collectively, on the GDP of a nation. But this problem is far more complex.

In a biological framework, micronutrients such as iron, iodine, and vitamin B12 are essential for normal brain development and functioning, as shown when profound deficiency is created in experimental animals, or clinically, in patients with severe nutrition deficiency diseases. Supplements helped in these cases, resulting in an enthusiastic push for macro- and micronutrient supplements in early childhood, eventually tying solely into stunting prevention. But this is an unbalanced approach, as a recent Lancet Global Health paper shows.

The study rigorously evaluated four adult cohorts from birth, from Brazil, Guatemala, Philippines and South Africa. The relative contributions of early-life height and schooling to adult IQ were assessed, and the study found that schooling and early cognitive development were most important for the attained adult IQ. Importantly, child height was not independently associated with adult IQ. Thus, arguments for nutritional interventions to reduce stunting in early childhood, to improve their adult IQ, earnings, and human capital, are simplistic — such claims are vastly exaggerated.

The message is clear: policy that seeks to improve cognitive development and adult human capital must not solely focus on the provision of nutrition for height. It requires equal and holistic policies on availability and quality of schooling and its social, emotional, and cognitive context. Nurture is much more than nutrition.

In clinical perspective, serious nutritional deprivation will undoubtedly impact brain development and nutrition. This speaks to making sure that seriously undernourished children should be are given nutritional attention. But in the current life setting, observed nutrient deficits in public health are usually of the milder variety, which can easily be met by simple dietary education. Prescribing mixtures or single (micro)nutrients as supplements to make “smarter” babies and adults is unwarranted and unwise.