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A more convincing take on prenatal maternal dietary effects on child IQ

Image credit: Nutrition and Pregnancy: Choline For Baby’s Development

Prenatal maternal nutrition is more likely to influence child cognitive abilities than fluoride. A new paper shows this by considering the effects of good or bad prenatal nutrition for the women in the Basash et al., (2016)  study that anti-fluoride campaigners promote. The new data shows that nutrition is more important than fluoride.

The Bashash et al. (2016) reported a weak relationship between prenatal maternal urinary fluoride and child cognitive outcomes or IQ (see Fluoridation: “debating” the science?). Anti-fluoride campaigners latched on to the paper because it seems to offer critical “evidence” for their claims that community water fluoridation lowers IQ. They argue that IQ, rather than the risk of dental fluorosis, should be the main consideration when considering community water fluoridation.

But a new study shows that prenatal maternal nutrition is a better predictor of neurodevelopmental outcomes for children than is urinary fluoride. This study used data from the same set of Mexican women/child pairs as Bashash et al., (2016).

Here is the citation for the new study:

Malin, A. J., Busgang, S. A., Cantoral, A. J., Svensson, K., Orjuela, M. A., Pantic, I., … Gennings, C. (2018). Quality of Prenatal and Childhood Diet Predicts Neurodevelopmental Outcomes among Children in Mexico City. Nutrients, 10(8), 1093.

Misrepresentation  of the Bashash et al., (2016) study

I have dealt with this in a number of articles. Basically my argument was not with the study itself (although it obviously lacks consideration of important risk-factors in it statistical analysis) but with the way anti-fluoride activists use it to draw unwarranted conclusions.

A key problem they ignore is that the relationships reported by Bashash et al., 2016 can explain only about 3% of the variation in the cognitive measurements. This strongly suggests that the relationship with prenatal urinary fluoride would probably disappear if more important risk-modifying factors were included in the statistical analysis. My article “Predictive accuracy of a model for child IQ based on maternal prenatal urinary fluoride concentration.”  explains this and is available online.

The new Malin et al., (2108) study now provides some risk-modifying factors, specifically diet, which explains the data better than does urinary fluoride.

Readers wishing to refer back to my earlier posts on misrepresentation of the Bashash et al., (2106) study can read:

Diet as a predictor of neurodevelopmental outcomes

The statistical analyses in this new paper are quite complex because the authors considered nutrient mixture and not simply each nutrient in isolation. Their argument for this is that we consume nutrients as mixtures and that interactions between nutrients is always possible.

The study, therefore, looked at the relationship of different neurodevelopmental outcomes in the children with prenatal maternal diet. Initially the authors considered the predictive ability of nutrition by considering “good” or “bad” diets based on U.S. dietary guidelines.

A bad diet during pregnancy may harm your future child’s neurodevelopment. Credit: © ivanmateev / Fotolia

Good maternal prenatal nutrition had a significantly positive effect on all the neurodevelopmental outcomes measured. In contrast, poor nutrition had a significantly negative effect on all the outcomes (see table below). Weighted Quartile Sums (WQS) were used to create indices for the individual diets.

I compared the predictive ability of prenatal maternal nutrition used here with the prenatal maternal urinary F approach used by Bashash et al., (2016) using data digitally extracted from their supplemental figures (S1 and S2 – see below). This was for the verbal development score of the children. Unfortunately, this was the only individual data presented.

Clearly, there is a lot of scatter in the data – to be expected where a number of risk-modifying factors are involved. However, the data showing a positive effect of good maternal prenatal nutrition on the verbal score of the children explains 7.1% of the variation. The data for poor prenatal nutrition explains 11.2% of the variation.

Compare this with the predictive ability of the data present by Bashash et al., (2016) where maternal prenatal urinary fluoride could only explain 3% of the variation of the child cognitive scores (see Maternal urinary fluoride/IQ study – an update).

Malin et al., (2018) were able to show which nutrients contributed most to the positive or negative neurodevelopmental outcomes of the children. They concluded:

“mothers who consumed more nutritious diets during pregnancy tended to have children with more favorable neurodevelopmental outcomes, while mothers who consumed less nutritious diets and/or higher levels of sodium, saturated fat, and/or sugar during pregnancy tended to have children with poorer neurodevelopmental outcomes. This suggests that the consumption of more comprehensively nutritious prenatal diets favorably affects child  neurodevelopment, while the consumption of less comprehensively nutritious prenatal diets may hinder it.”

Individual nutrients affected specific neurodevelopmental factors but they reported that prenatal dietary thiamine, vitamin B6, monounsaturated fats, fibre and calcium had beneficial effects. In contrast, lower monounsaturated fat, lower thiamine, lower fibre and higher saturated fat were associated with lower neurodevelopmental scores for the children.

Conclusions

If anti-fluoride activists are really concerned about child IQ and other aspects of child neurodevelopment then they should be campaigning on the importance of nutrition during pregnancy and stop diverting us by scaremongering about community water fluoridation.

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