Atopic conditions such as asthma, eczema and allergic rhinitis (runny nose), along with allergic conjunctivitis, usually begin in childhood; but could diet during pregnancy help to allergy-proof future generations? Lisa Patient investigated this issue in the Summer 2016 edition of #ion_nutrition Optimum Nutriton Magazine
Although there is a known genetic element in developing atopic allergies, research is also investigating whether a woman’s diet and lifestyle during pregnancy could help to reduce the risk.(1)
Fats
Studies suggest that omega fats could offer a protective mechanism against atopic allergies. Several clinical studies have found that women who take a daily omega-3 fish oil supplement during pregnancy reduce the risk of allergies for their children. An explanation for this may be in the impact the fish oil has on the chemicals transferred to the baby via the umbilical cord, with evidence to show that taking fish oil supplements lowered the levels of inflammatory chemicals called cytokines in the cord blood. (2)
However, getting sufficient omega-3s into your body via diet in pregnancy can be challenging. This is because studies typically use a dose of over 2g of fish oil per day – the equivalent of about two portions of oily fish. Current advice, however, is to limit oily fish intake during pregnancy
to no more than two portions a week because of mercury levels found in fish. Supplementation with the fish oils DHA and EPA is considered safe, but cod liver oil is not because it contains vitamin A, which is not recommended in high amounts during pregnancy.(3,4)
There is evidence to suggest that women eating a high amount of omega-6 rich foods (such as vegetable oils and margarine) may have an increased risk of their children developing allergies. A study of 77′ mother-child pairs that looked at meat consumption in pregnancy, a rich source of omega-6 fats, concluded that higher maternal meat intake may lead to an increased risk of eczema.(5)
Antioxidants
One nutrient that has been contra- indicated for pregnancy is vitamin A. One study published in 1995, found high daily doses (>10,000iu) of vitamin A may lead to birth defects,(6) and the NHS currently advises against high amounts of vitamin A during pregnancy. (15) However, a mother’s diet that is rich in the plant pre-cursor for vitamin A called beta-carotene may be protective against the development of eczema in the child.(7) Beta-carotene, found in carrots, sweet potato, mango, peppers, chard, spinach and kale, is a type of nutrient called a carotenoid, which is a powerful antioxidant known to protect the skin from UV damage.
Several recent studies also suggest that vitamin E may protect against allergies, particularly asthma. This is because it is utilised in the healthy development of cells in the airways and lungs, which may impact the risk of breathing-related allergies.(8) Mothers are advised to eat foods rich in vitamin E such as nuts and seeds, avocado, olive oil, whole wheat and rice. But, as with vitamin A, supplementation of vitamin E should be treated with caution. A paper published in2016 suggested that high vitamin E intake could possibly be a contributing factor to congenital heart defects in babies.(9)
Avoiding foods
So should certain foods be avoided during pregnancy? ln children, the protein in cow’s milk is a common trigger for eczema, but there is no evidence to link eating dairy foods during pregnancy to an increased risk for the child. Likewise, the NHS has changed its advice about eating peanuts,
because there is no evidence to suggest that eating peanuts during pregnancy increases the risk of peanut allergy, unless there is already a family history of this allergy. ln fact, a large study from Denmark found that eating peanuts during pregnancy was associated with reduced risk of asthma in children.(10)
Vitamin D
ln 2014, the Royal College of Obstetricians and Gynaecologists published a comprehensive paper on the role of vitamin D, the sunshine vitamin, in pregnancy. Evaluation of scientific papers established associations between vitamin D deficiency and complications in childbirth such as pre-eclampsia, high blood pressure, likelihood of caesarean delivery and gestational diabetes. Children were also found to have a lower birth weight and to be more likely to develop hay fever or allergies if the mother was vitamin D deficient. Given the high incidence of vitamin D deficiency in
the UK, this is likely to be a nutrient that should be supplemented during pregnancy, and a simple blood test can determine whether this is the case.(11)
Stress and lifestyle
Pregnancy can be a stressful time for women for many reasons, and studies are showing that this may also be a factor in babies developing atopic allergies.In 1998, a major ice storm in Quebec, Canada caused a power outage that lasted several weeks, putting expectant mothers in the area under significant stress. An evaluation of the children at age 11 showed a significantly high incidence of asthma in the storm children, particularly amongst the girls. Interestingly, the outcome of this investigation linked the high incidence of asthma to the mother’s subjective stress, which was how she thought and felt about the situation, rather than the objective hardship, which was a measure of how much disruption the event caused her.(12)
This may seem to be more a case of environment rather than nutrition, but babies born to mothers who were under stress during pregnancy have been found to have lower levels of ‘good’ bacteria in their guts.(13) This has significance, because it is known that children with poor levels and variety of gut bacteria are at higher risk of developing eczema.(14)
These associations between atopic allergy risk and a mother’s prenatal stress levels also throw a confounding factor into the research linking specific nutrients to allergy risk – because they highlight that it is almost impossible to control all the variables that affect women during pregnancy when conducting clinical trials.
Staying well during pregnancy
In conclusion, there seems to be some evidence that omega-3 fats, vitamin E, beta-carotene, and vitamin D may all have some allergy-proofing mechanisms. However, only vitamin D and omega-3 fats should be supplemented along with a pregnancy-formulated multivitamin and mineral. This, of course, goes hand- in-hand with a diet rich in minerals and antioxidants from fruits and vegetables, nuts and seeds, and lean proteins such as chicken and legumes. And trying to keep stress under control can only help.
1. Irwin McLean WH (2011). The allergy gene: how a mutation in a skin protein revealed a link between eczema and asthma F1000 Med Rep.; 2011; 3: 2. Published online 2011 Jan 14. doi: 10.3410/M3-2 PMCID: PMC3042307
2. Dunstan JA1, Mori TA, Barden A, Beilin LJ, Taylor AL, Holt PG, Prescott SL (2003). Maternal fish oil supplementation in pregnancy reduces interleukin-13 levels in cord blood of infants at high risk of atopy. Clin Exp Allergy; Apr;33(4):442-8.
3. Greenberg JA, Bell SJ, Ausdal WV (2009). Omega-3 fatty acid supplementation during pregnancy. Rev Obstet Gynecol; 2008 Fall; 1(4): 162–169.
4. NHS Choices, Why should I avoid some foods during pregnancy? Accessed at http://www.nhs.uk/chq/Pages/917.aspx
5. Saito K1, Yokoyama T, Miyake Y, Sasaki S, Tanaka K, Ohya Y, Hirota Y (2010). Maternal meat and fat consumption during pregnancy and suspected atopic eczema in Japanese infants aged 3-4 months: the Osaka Maternal and Child Health Study. Pediatr Allergy Immunol; 2010 Feb;21(1 Pt 1):38-46. doi: 10.1111/j.1399-3038.2009.00897.x. Epub 2009 Jun 23.
6. Rothman KJ1, Moore LL, Singer MR, Nguyen US, Mannino S, Milunsky A (1995). Teratogenicity of high vitamin A intake. NEngl J Med. ; Nov 23;333(21):1369-73.
7. Miyake Y1, Sasaki S, Tanaka K, Hirota Y (2010). Consumption of vegetables, fruit, and antioxidants during pregnancy and wheeze and eczema in infants. Allergy; Jun 1;65(6):758-65. doi: 10.1111/j.1398-9995.2009.02267.x. Epub 2010 Jan 22.
8. Miller DR1, Turner SW, Spiteri-Cornish D, Scaife AR, Danielian PJ, Devereux GS, Walsh GM (2015). Maternal vitamin D and E intakes during early pregnancy are associated with airway epithelial cell responses in neonates. Clin Exp ; May;45(5):920-7. doi: 10.1111/cea.12490.
9. Smedts HP1, de Vries JH, Rakhshandehroo M, Wildhagen MF, Verkleij-Hagoort AC, Steegers EA, Steegers-Theunissen RP (2009). High maternal vitamin E intake by diet or supplements is associated with congenital heart defects in the offspring. BJOG; Feb;116(3):416-23. doi: 10.1111/j.1471-0528.2008.01957.x.
10. Maslova E1, Granström C, Hansen S, Petersen SB, Strøm M, Willett WC, Olsen SF (2012). Peanut and tree nut consumption during pregnancy and allergic disease in children-should mothers decrease their intake? Longitudinal evidence from the Danish National Birth Cohort. J Allergy Clin Immunol; Sep;130(3):724-32. doi: 10.1016/j.jaci.2012.05.014. Epub 2012 Jun 27.
11. Royal College of Obstetricians and Gynaecologists (2014). Vitamin D in Pregnancy Scientific Impact Paper No. 43 June 2014 https://www.rcog.org.uk/globalassets/…/vitamin_d_sip43_june14.pdf
12. Turcotte-Tremblay A, Lim R, Laplante DP, Kobzik L, Brunet A, and King S (2014). Prenatal Maternal Stress Predicts Childhood Asthma in Girls: Project Ice Storm. BioMed Research International; vol. 2014, Article ID 201717, 10 pages, 2014. doi:10.1155/2014/201717
13. Maartje A.C. Zijlmans, Katri Korpela, J. Marianne Riksen-Walraven, Willem M. de Vos, Carolina de Weerth (2015). Maternal Prenatal Stress is Associated with the Infant Intestinal Microbiota. Psychoneuroendocrinology; DOI: 10.1016/j.psyneuen.2015.01.006
14. Björkstén B1, Sepp E, Julge K, Voor T, Mikelsaar M(2001). Allergy development and the intestinal microflora during the first year of life. J Allergy Clin Immunol; Oct;108(4):516-20.
15. www.nhs.uk/Conditions/vitamins-minerals/Pages/Vitamin-A.aspx