Maternal peanut consumption affects infant sensitization, allergy
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Key takeaways:
- Infants whose mothers consumed less than 5 g of peanuts a week had less sensitization and allergy.
- Baseline skin prick test stratum and a lack of peanut consumption while breastfeeding also were risk factors.
Infants whose mothers consumed less than 5 g a week of peanuts while breastfeeding experienced a significant protective effect against peanut sensitization, according to a study published in Annals of Allergy, Asthma & Immunology.
These infants also experienced a noticeable but not statistically significant protective effect against peanut allergy, Michael Brandwein, PhD, cofounder and vice president of research and development at MYOR Diagnostics Ltd., and colleagues wrote.
“This study was inspired by the fact that data on allergen introduction as a method to prevent allergy is somewhat limited,” Brandwein told Healio.
Brandwein and his colleagues recognized a gap in understanding how maternal diet, particularly during breastfeeding, potentially could impact infant allergenicity.
“We were fortunate to find relevant data in the publicly available dataset from the LEAP study that had the necessary data to explore this question, and this led us to focus specifically on peanut consumption,” Brandwein said.
Study design, results
The study involved 303 infants at high risk for peanut allergy due to egg allergy and/or severe eczema enrolled at age 4 to 11 months into the LEAP study and randomly assigned to the group of infants who avoided peanut consumption.
The 281 infants who were breastfed in this group included 181 whose mothers did not consume any peanuts; 69 whose mothers consumed less than 5 grams of peanuts each week, classified as low consumption; and 31 whose mothers consumed 5 grams or more each week, classified as high consumption.
Among the mothers who consumed peanuts, the median amount of maternal peanut protein consumed during lactation was 2.55 g/week. Specific medians included 1.45 g/week (interquartile range [IQR], 0.79-2.6) for the low group and 16.1 g/week (IQR, 7.5-26.11) for the high group.
The researchers called the correlation between peanut consumption while pregnant and while breastfeeding significant (r = 0.87), but there was no correlation between total household consumption of peanuts and consumption during pregnancy or breastfeeding.
A univariate logistic regression model found a positive association between low maternal peanut consumption and peanut sensitization at age 60 months.
Compared with the infants of mothers who consumed no peanuts or high amounts of peanuts while breastfeeding, the infants whose mothers consumed less than 5 grams of peanuts a week had less frequent peanut sensitization (P = .027) and allergy (P = .073).
Specifically, 25.8% of the high consumption group, 10.1% of the low consumption group and 25.4% of the group with no consumption had wheals of 3 mm or larger in skin prick testing (P = .027) at age 60 months, indicating sensitization.
Similarly, 19.4% of the high group, 7.2% of the low group and 18.8% of the group with no consumption had a positive peanut oral food challenge at age 60 months, indicating allergy.
In a univariate analysis that included exposure to peanut protein before solid feeding begins, maternal consumption while breastfeeding and environmental exposure, low maternal consumption during breastfeeding significantly reduced peanut sensitization at age 60 months compared with infants in the groups with high and no consumption.
The researchers said there was a similar trend when they analyzed peanut allergy at age 60 months, although it was not significant.
Birth weight, gestational age, birth type, breastfeeding duration, paternal history of asthma, maternal history of eczema, rhinoconjunctivitis or food allergy did not significantly contribute to risk for sensitization or allergy, the researchers continued.
Ethnicity was a significant contributor to sensitivity (OR = 0.47; 95% CI, 0.22-0.99) and allergy (OR = 0.31; 95% CI, 0.14-0.7) at age 60 months, as was baseline peanut SPT stratum for sensitivity (OR = 4.87; 95% CI, 2.13-11.12) and allergy (OR = 3.04; 95% CI, 1.24-7.47).
A lack of maternal peanut consumption while breastfeeding also was a risk factor for sensitivity (OR = 3.25; 95% CI, 1.36-7.77) and allergy (OR = 2.62; 95% CI, 1.01-6.81) at age 60 months.
Baseline SCORing Atopic Dermatitis scores greater than 40 were risk factors for sensitivity (OR = 2.78; 95% CI, 1.32-5.85) and allergy (OR = 2.4; 95% CI, 1.04-5.55) at age 60 months as well.
Maternal asthma was a risk factor for sensitivity at age 60 months (OR = 2.87; 95% CI, 1.25-6.61) but not for allergy.
Other significant risk factors for allergy at age 60 months included sex (OR = 0.42; 95% CI, 0.18-0.96), paternal eczema (OR = 0.4; 95% CI, 0.17-0.93), paternal rhinoconjunctivitis (OR = 2.69; 95% CI, 1.14-6.35) and any positive non-peanut SPT (OR = 3.49; 95% CI, 1.22-9.99).
Conclusions, next steps
“One of the most surprising results of our study was that a protective effect against peanut allergenicity in infants was only noticeable among mothers who consumed moderate amounts of peanuts,” Brandwein said.
These findings may suggest a certain threshold of peanut exposure necessary to achieve a protective effect, he continued, as the groups with no consumption and high consumption did not show the same protective benefits. They also suggest a nuanced interaction between oral allergen exposure and environmental exposure during breastfeeding, he continued.
“The results are surprising because one might intuitively expect that higher peanut consumption would lead to a stronger protective effect. Instead, we found that only moderate consumption provided noticeable protection,” Brandwein said.
“This suggests that there is a fine balance that needs to be struck between oral allergen exposure and cutaneous allergen exposure to achieve protection, which underscores the complexity of the human immune system,” he said.
Although there was no correlation between environmental exposure to peanut and maternal consumption of peanut, the researchers said that maternal consumption still may be directly correlated with environmental exposure and, therefore, transcutaneous exposure.
Minimal consumption of peanuts during lactation may provide enough oral exposure to peanut protein for the infant’s immune system to develop tolerance without triggering subcutaneous sensitization, the researchers suggested.
Meanwhile, they continued, the transcutaneous exposure resulting from high maternal peanut consumption may override or preempt oral tolerance, putting the infant at risk for peanut allergy outcomes.
Based on these findings, the researchers concluded that low levels of peanut consumption during breastfeeding in the context of delayed peanut introduction protects children against peanut sensitization at age 60 months.
“While the results of our study are still preliminary and more research is needed before changing clinical practice, our findings might provide doctors with a new perspective on dietary advice for breastfeeding mothers,” Brandwein said.
For example, he said, doctors may consider advising mothers to maintain low peanut intake during breastfeeding as a potential method to protect infants from peanut allergenicity.
“However, they should also caution that both no and high intake did not show the same protective effect,” Brandwein said. “This should be used as a steppingstone for further discussion on the importance of early allergen introduction when the infant begins eating solid foods.”
Next, the researchers expect to further explore the threshold for breastmilk-induced oral tolerance to peanuts as well as the threshold for transcutaneous peanut sensitization in the post-natal period.
“We also plan to investigate the impact of milk allergen exposure through both breastmilk and formula,” Brandwein said. “These future studies will help us better understand the role of allergen exposure through different feeding methods in infant allergenicity.”
For more information:
Michael Brandwein, PhD, can be reached at michael@myorcare.com.
Perspective
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Theresa Bingemann, MD, FACAAI, FAAAAI
The data presented in this study is not strong enough to say there should be a change in practice among high-risk families. There were small numbers in each group, and these results conflict with that of other studies that examined this question.
A challenge in interpretation of this data is the significant inter-individual variation in the secretion of dietary proteins in breast milk in regard to timing and amount of protein. We do not know how much peanut protein, if any, was excreted by the women who consumed peanut. We also do not know if this varies between atopic and nonatopic women.
We do not have clear enough data to say whether peanut consumption and how much consumption is helpful or hurtful. Furthermore, based on the retrospective design of this study, there may be a recall bias with respect to peanut consumption in pregnancy and breastfeeding in this group. We also do not know the reasons, if any, that some moms did not consume peanut. Perhaps moms who avoided peanut during pregnancy and lactation did so because they had a child at home with peanut allergy.
I have never seen a clear pattern one way or the other. However, we do not routinely ask about peanut consumption in pregnancy. We do know that studies of maternal avoidance diets to prevent allergy have led to poor maternal weight gain and were not effective in allergy prevention.
During lactation, the question of whether a mom can continue with peanut in her diet if the child is peanut allergic does come up. In that case, if the child is not exhibiting any adverse effects, mom can continue with it in her diet. Most infants tolerate this just fine. As allergists, we see a biased sample — those who have allergic disease already.
It is too early to say that any changes should be made regarding peanut ingestion during pregnancy and breastfeeding, given this is a small, retrospective study. The potential impact of this data, while interesting, is limited by the fact they are looking at a small segment of the population — high-risk children with egg allergy and severe eczema.
Furthermore, the researchers appropriately looked at the group of pregnant women who avoided peanut to see the impact of maternal peanut consumption during pregnancy and lactation. However, standard of care is now early introduction of peanut to prevent allergy, as we have a randomized controlled trial showing it is effective in peanut allergy prevention. This is the highest quality of evidence we can get. Physicians should focus on early introduction.
More high-quality research is needed to clarify the impact of maternal consumption of peanut during pregnancy and breastfeeding before people should change their practice. Fortunately, a prospective randomized controlled study, the PrEggNut study, is seeking to answer this question in another high-risk population.
This study is designed to examine the impact of a maternal diet rich in peanut and egg from 23 weeks of gestation through 4 months of breastfeeding on infants with at least two biological family members (mother, father or siblings) with physician-diagnosed allergic diseases.
We do not have clear enough data to say whether peanut consumption and how much consumption is helpful or hurtful. Furthermore, based on the retrospective design of this study, there may be a recall bias with respect to peanut consumption in pregnancy and breastfeeding in this group. We also do not know the reason why some moms did not consume peanut.
While we wait for this data, we know that there is an effective strategy for peanut allergy prevention, as early introduction of peanut protein has been shown to reduce peanut allergy regardless of whether peanut is or is not consumed during pregnancy and breastfeeding.
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