Dr. Phil May’s research group at the NRI studies the prevalence of Fetal Alcohol Spectrum Disorders (FASD) in humans. The recent addition to the NRI faculty of Dr. Susan Smith now provides an avenue toward understanding how maternal nutrition might affect the relationship between alcohol and FASD through the use of animal models. Two recent papers from these research groups illustrates this synergy.
Should you abstain from drinking if you are breastfeeding?
While there is convincing evidence that drinking alcohol during pregnancy is harmful to the developing fetus, much less is known about the risks of drinking during breastfeeding. In “Everyone Drink Up: This holiday season, there is no reason to pump and dump,” the author argues that the blood alcohol level of a nursing baby would be minimal, even if the mother had recently consumed several glasses of wine (where minimal is defined as equal to the baby drinking 1.5 ounces of beer). Similar arguments can be found on numerous parenting websites. But decades of research shows that prenatal alcohol exposure affects fetal growth and development; we also know that early infancy is a time of rapid physical growth and neurological development. Since infants break down alcohol more slowly than adults, any effects of that 1.5 ounces of beer will be magnified.
What they did:
In “Breastfeeding and maternal alcohol use,” NRI researcher Phil May, Ph.D. and colleagues report the results of a retrospective analysis of the effects of postpartum drinking during breastfeeding on several aspects of children’s growth through age seven. Rigorous data on the effects of alcohol in humans is scarce, in large part because there is no ethical way to conduct controlled experiments. As a result, what we know comes from surveys taken after nursing ends of mothers’ drinking habits during the breastfeeding period. One study from 1989 (Little et al., 1989) found that maternal drinking impacted motor development, but not mental development, in breast-fed infants at 1 year of age. Other studies have found that nursing after drinking can affect the child’s sleep patterns. Most studies are of limited duration and scope, so this research from Dr. May (1,000 mothers, seven-year follow up) is notable.
The findings revealed a clear correlation between a mother’s drinking behavior and her child’s weight and verbal IQ. Compared to children of mothers who did not drink during pregnancy or breastfeeding, children of mothers who drank during breastfeeding weighed less and had lower IQs. Children of mothers who drank during pregnancy (but not during breastfeeding) had even greater reductions in weight and IQ. Continuing the trend of increasing alcohol exposure, children of mothers who drank during pregnancy and breastfeeding weighed the least and had the lowest IQs of the four groups.
What it means:
Dr. May’s study shows that drinking alcohol during the breastfeeding period can affect a child’s physical growth and mental development. Some of the mothers who drank during the breastfeeding period likely consumed large amounts of alcohol; as the alcohol content of milk was not measured, direct comparison to other studies is difficult. Regardless, this study shows that alcohol-related developmental impairments persist at least through age seven, indicating that damage incurred at early developmental stages can have long-lasting impact.
How does a mother’s diet affect the severity of FASD?
The subjects of Dr. Mays’s study were South African women and children. Mothers in this group breast fed for comparatively more months and had poorer nutrition, both of which could contribute to negative outcomes. In fact, poor maternal nutrition during pregnancy is known to worsen FASD outcomes. Maternal iron deficiency is the most common micronutrient deficiency during pregnancy, and has been found to exacerbate a subset of the clinical symptoms of FASD. While it is easy to administer dietary iron supplements during pregnancy, it is also important to understand how maternal alcohol exposure affects fetal iron levels, and how fetal iron levels are linked to FASD symptoms. In a recent paper in the Journal of Nutrition, Dr. Smith used the rat model to examine the fetal and maternal micronutrient distribution as a consequence of maternal alcohol exposure and iron deficiency.
What they did:
Smith’s group fed rats either a normal or iron-deficient diet, with or without an alcohol challenge during pregnancy. Concentrations of iron in the mothers’ liver were decreased by an iron-deficient diet, as expected, but were not altered by alcohol exposure. In contrast, prenatal alcohol exposure resulted in increased storage of iron in the fetal liver and decreased available iron for other tissues, including the brain and red blood cells. This shows that the maternal and fetal responses to maternal alcohol exposure are different.
Smith’s group then sought to identify potential responsible factors. They found that gestational alcohol exposure altered the expression of iron transport/storage proteins in the fetal, but not maternal liver. Specifically, levels of the iron-storage protein ferritin increased 66% in iron-deficient fetal livers. This means that iron in the fetus will be sequestered in the liver and unavailable to other tissues, and that this effect is magnified in the presence of maternal iron deficiency. Alcohol-exposed fetuses were anemic, and this anemia worsened when combined with a maternal iron-deficient diet.
What it means:
The findings from Dr. Smith’s research suggest a partial explanation for the fetal brain’s vulnerability to alcohol, as alcohol exposure significantly alters the iron distribution between the brain and liver. Thus, prenatal alcohol exposure induces an iron-deficient state in the developing brain, even when the maternal diet is not clinically iron deficient. This may suggest that dietary iron supplementation during pregnancy may mitigate some alcohol-induced injury. Although this study did not look at dietary supplementation during nursing, it is quite possible that the effects noted in Dr. May’s study were aggravated by the maternal iron deficiency.
“Everyone Drink Up.” www.slate.com/articles/double_x/the_kids/2014/12/breast_feeding_and_alcohol_it_s_fine_to_drink_while_nursing.html
Huebner, SM, Blohowiak, SE, Kling, PJ, & Smith, SM (2016). “Prenatal alcohol exposure alters fetal iron distribution and elevated hepatic hepcidin in a rat model of fetal alcohol spectrum disorders.” J Nutr. 146:1180-1188.
Little RE, Anderson KW, Ervin CH, Worthington-Roberts B, Clarren SK (1989). “Maternal alcohol use during breast-feeding and infant mental and motor development at one year.” N Engl J Med. 321:425-430.
May PA, Hasken JM, Blankenship J, Marais AS, Joubert B, Cloete M, de Vries MM, Barnard R, Botha I, Roux S, Doms C, Gossage JP, Kalberg WO, Buckley D, Robinson LK, Adnams CM, Manning MA, Parry CD, Hoyme HE, Tabachnick B, Seedat S (2016). “Breastfeeding and maternal alcohol use: Prevalence and effects on child outcomes and fetal alcohol spectrum disorders.” Reprod Toxicol. 63:13-21.