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Abstract
Diet diversity is a term used to define the number of foods or food groups eaten over a certain period. In turn, diet quality describes food patterns and is usually summarised by using diet indices. There are a wide range of dietary and environmental aspects that have been associated with the patho-ethiology of allergic diseases. One of the factors includes nutrition of the pregnant and breast feeding women, infant and child. Studies focusing on the intake of specific nutrients have failed to provide any clear guidance on allergy prevention. Allergen avoidance for the pregnant and breast feeding women is not recommended and timely introduction and consumption of food allergens when infants start to eat is recommended. Nutritional prevention strategies have shifted their focus from single nutrients and foods to addressing the to the overall during pregnancy, breast feeding, and early life. Only one diet index in pregnancy, as a measure of the overall diet, has shown a reduction in childhood allergic disease, referred to as the maternal diet index. Limited data exist to support the role of the Mediterranean diet in pregnancy and offspring respiratory outcomes. There no studies focusing on diet indices in infancy and childhood allergy outcomes. Infant diet diversity and maternal healthy diet diversity during pregnancy has been associated with a reduced prevalence of childhood allergic diseases. There is a need to perform randomised controlled trials using overall dietary intake to support international food allergy guidelines.
- Microbiome
- Food allergies
- Nutritional treatment
- Skin disorders
Data availability statement
Data sharing not applicable as no datasets generated and/or analysed for this study.
This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See: https://creativecommons.org/licenses/by/4.0/.
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Introduction
Allergic diseases negatively impact the quality of life, school performance and income1 2 and may be fatal.3 4 An estimated 300 million people worldwide is affected by asthma5 which includes 10.4% of US children.6 In the USA, 20% of children suffer from eczema/atopic dermatitis and up to 30% worldwide.5 7 Food allergies are rising dramatically, as indicated by the World Allergy Organisation5 and the National Academies of Medicine.8 In the USA, 7.5% of children suffer from food allergies. Of these, 40% have multiple food allergies, and 42% have experienced a severe reaction.9 Up to 75% of children develop tolerance to baked milk egg or milk with age and a large fraction of these develop tolerance to uncooked milk and egg but this is not true for most other food allergies.8 Having a food allergy may therefore indicate a lifetime of suffering from food allergies.
A variety of interventions for allergy prevention have been tried during multiple time periods of life. Interventions have included food and/or environmental allergen avoidance,10–13 topical skin treatments, food and/or environmental allergen introduction,14–16 prebiotic intake,17 probiotic intake,18 nutrient supplementation or intake of specific foods.19 Prevention studies have focused on changing the maternal diet in pregnancy and breast feeding by addressing nutrient and food intake and/or food allergen avoidance. Systematic reviews20–22 summarising this body of work showed no association between any of these factors studied and offspring allergy outcomes, other than perhaps taking probiotics in pregnancy, breast feeding and prevention of atopic dermatitis in early life.22 A European Academy of Allergy and Clinical Immunology (EAACI) systematic review,21 indicated that high-dose vitamin D supplementation taken during pregnancy may reduce offspring asthma and wheeze. A systematic review by Garcia-Larsen et al 20 established that there is no benefit of maternal dietary changes during breast feeding on the prevention of offspring allergy outcomes. Current food allergy prevention guidelines are limited by the lack of consistent study outcomes and recommend that there is no need for pregnant or lactating women to exclude food allergens from their diets (table 1).23–26
International guidelines on food allergy prevention in pregnancy and lactation
No single nutrient or dietary pattern in infancy has been shown to prevent allergies.20 The ‘dual allergen hypothesis’ describes an association between atopic dermatitis and subsequent food allergy.27 It hypothesises that exposure to food allergens through the eczematous skin, can lead to food allergy which may be prevented by timely and early oral intake of food allergens. Observational data from the Isle of Wight28 and Australia29 supports the hypothesis that early life atopic dermatitis is associated with development of food allergy. This led to dietary intervention trails focusing on consumption of food allergens during early infancy for food allergy prevention.30 These studies concluded that peanut and well-cooked egg consumption in early infancy significantly reduce the prevalence of peanut14 31 and egg15 allergy, respectively.
This review will focus on overall dietary intake, focusing on diet diversity and diet indices during pregnancy, breast feeding and infancy, in allergy prevention. Diet diversity is a term used to define the number of foods or food groups eaten over a certain period.32 Diet variety is synonymous with diet diversity.32 Diet diversity can be measured by counting, for example, foods, food groups, food allergens and the period studied should be clearly indicated. Diet indices describe a pattern of food intake such as the Mediterranean diet or the Western diet.32
Mechanism of action
Maternal diet
Maternal nutrient intake in pregnancy has been associated with offspring DNA methylation,33 34 cord blood cytokines35 and infant microbiome.36 One study reported no relationship between the inflammatory potential of the maternal diet during pregnancy and cord blood cytokines.37 The relationship between diet diversity during pregnancy and maternal or infant microbiome has not been studied.
Infant diet
A more diverse diet may change microbiome composition and function and thereby tolerance development. The gut microbiota’s composition and function significantly affect mucosal immune responses and its potential for immune modulation. Microbial metabolites including short chain fatty acids, including butyrate, affect T-regulatory cell function and could therefore reduce allergy outcome.38 39 Diet diversity32 40 has been shown to increase diversity of gut microbiome species and butyrate production. Increased intake of family foods indicating and increase in diet diversity or variety during the first year of life, has been linked with an increase in gut microbiome diversity.41 An infant diet rich in fruit, vegetables, fish and yoghurt also characterised a gut microbiome with higher butyrate production.38 In this study, butyrate production was associated with reduced food allergy and atopic dermatitis outcomes.38 Butyrate production plays a role in tolerance development, through upregulation of T-regulatory cells, reduction in Th2 cytokine production42 and modulating immune-regulating components in both the gut and tissues.43–47
Studies focusing on food allergy reported that in high-risk infants,48 higher diet diversity scores in 3–5 months, indicating the very early introduction of solids foods, were associated with an increase in microbial diversity at 6 months based on Chao1 index. Again, in high-risk infants, levels of pro-inflammatory and Th2 cytokines and chemokines, were higher in infants with lower diversity than higher diversity scores. The Enquire About Tolerance (EAT) study indicates that based on the Shannon index, food allergen diversity in the first year of life was associated with a significant increase in microbial diversity as well as higher levels Proteaceae and proteobacteria.49
Increased nutrient intake with immunomodulatory potential
Diet diversity is an independent measure of dietary consumption, but it is not a measure of diet quality as diet diversity most often does not consider portion size or frequency of intake.50 However, diet indices may be a suitable measure to identify increased intake of immunomodulatory nutrients such as omega-3 fatty acids and non-digestible fibres.20 51
Exposure to food antigens
Questions were raised about the relationship between food diversity and food allergen diversity and whether an increase in one may lead to a reduction in another. Two studies reassuringly indicate that an increase in allergen diversity does not negatively affect overall diet diversity.52 53
Diet diversity in pregnancy and allergy outcomes
One study has explored an association between diet diversity in pregnancy and childhood allergic diseases.54 This reported that increased maternal diet diversity in pregnancy was significantly associated with reduced odds of child overall allergy, atopic dermatitis, asthma and wheeze by 4 years. On the contrary, increases in maternal unhealthy diet diversity scores were significantly associated with an increase in the odds by being diagnosed with atopic dermatitis. Total diet diversity, based on both healthy and unhealthy diversity, during pregnancy did not show an association with any of the childhood allergic diseases by 4 years.
Diet indices in pregnancy and allergy outcomes
Five diet indices in used to measure diet intake in pregnancy against offspring allergic diseases have been studied: the healthy eating index,54–58 the diet inflammatory index (DII)57 59 and the Mediterranean diet index,55 60–63 the maternal diet index, and dietary advanced glycation end products intake.37 Diet indices used in pregnancy are summarised in table 2.64–68
Diet indices studied during pregnancy
Healthy eating indexes
Four studies studied the relationship between healthy eating in pregnancy and childhood allergic diseases (table 3). The Food Allergy and Research study (FAIR), UK, and the Alternate Healthy Eating Index modified for pregnancy (AHEI-P) studied associations with child allergic diseases at 3 and 10 years.56 The FAIR study showed no association between the AHEI-P and sensitisation to any food and/or aero-allergen or parent-reported allergic diseases at these two-time points. The Project Viva cohort (USA)55 showed no association between AHEI-P and recurrent wheeze in 3-year-old children. Data from Ireland,57 however, indicated that higher HEI-2015 scores were associated with lower odds of asthma by 10 years of age. Using data from the Health Start cohort (USA), Venter et al 69 70 reported that higher pregnancy HEI-2010 scores were significantly associated with reduced odds of child diagnosis of ‘any allergy excluding wheeze’, allergic rhinitis, atopic dermatitis, asthma and wheeze by 4 years of age.
Summary of observational studies focusing on diet indices in pregnancy and offspring allergy outcomes
Diet inflammatory index
Three studies (table 3) have looked at the association between the DII in pregnancy and the prevalence of childhood asthma, wheeze or lung function.57 59 Data from Ireland57 indicated an association between higher pregnancy DII scores and child asthma by 10 years. The Project Viva (USA) study indicated an association between DII scores in pregnancy with childhood wheeze trajectories, up to 7.5 years of age.59 No association with childhood asthma was shown.59 US data from (Healthy Start study)58 showed no association between the DII scores during pregnancy37 and childhood allergy outcomes up to 4 years.
Mediterranean diet indexes
The Mediterranean diet (table 3), in its traditional format, is considered as a healthy eating pattern that protects against the development of many diseases,71 72 which leads to interests in its association with childhood allergic diseases. Six cohorts have investigated the association between the Mediterranean diet index and childhood allergy outcomes55 60–63 71 (two from Spain, one from Greece and Spain, one from the USA, one from Mexico and one from the UK). Five studies reported on infant wheeze,55 60–62 71 five studies reported on rhinitis, atopic dermatitis and/or eczema,55 60 62 63 71 two studies investigated sensitisation to food/aero-allergens55 62 and three studies reported on childhood asthma.55 63 71 Five55 60 62 63 71 of the six studies found no association between the Mediterranean diet index and the allergic outcomes studied. One study showed an association between increased childhood persistent wheeze, atopic wheeze and atopy with a reduced Mediterranean diet index score.61 Another study63 reported an association between the Mediterranean diet score and childhood lung function.
Dietary ages intake
The Healthy Start study,58 did not find any association between intake of advanced glycation end products68 during pregnancy and offspring allergy outcomes including food allergy, atopic dermatitis and asthma by 4 years.
The differences in study outcomes are based on the diet indices studied. May be due to different methods used to capture diet intake, which was then used to calculate the diet indices, and different definitions used for disease outcomes. Based on this data, a Delphi panel from EAACI32 agreed that there was no consistent diet pattern in pregnancy associated with offspring allergy outcomes and recommended that study measures should be standardised and that diet indices should be developed specifically tailored to be associated with childhood allergic diseases.
Diet diversity and diet indices during breast feeding
The association between diet diversity and diet indices in lactation on offspring allergic diseases has not been studied.
Diet diversity during infancy and allergy outcomes in the infant
Observational data consistently show an association between increased infant diet diversity and a reduction in childhood food allergy,52 73 74 asthma73 75 and allergic rhinitis.75 The association between infant diet diversity and childhood atopic dermatitis is however still unclear75–83 (table 4, box 1).
Diet diversity in infancy and allergy outcomes
Diversity definitions used—modified from Fiocchi et al22 and Roduit et al82
Diet diversity definition
Austria, Finland, France, Germany and Switzerland—PASTURE
Diet diversity in this study was defined as the 15 foods commonly eaten by 80% of the children in the study in the first year of life, which also included all food allergens: any cow’s milk, yoghurt, other milk product; eggs; nuts; vegetables or fruits; cereals; bread; meat; fish; soy; margarine or butter; cake; and chocolate. A second definition was also used, including the six major foods introduced in the first 6 months or first 12 months of life, which did not include all food allergens: vegetables or fruits; cereals; bread; meat; cake; and yoghurt.73
New Zealand
Cow’s milk, cereals, vegetables, dairy products, meat, fruit, egg/related products, other foods.77–79
Germany GINI study (GINI plus)
Dairy products, egg, cereals, legumes, vegetables, fruits, nuts, meat products, fish and other foods.76
Germany LISA study (LISA plus) Forty-eight food items were grouped into eight food groups: (1) vegetables (avocado, cauliflower, beans, broccoli, peas, cucumbers, carrots, potatoes, white cabbage, turnip, cabbage, lenses, celery, asparagus, spinach, tomatoes, onion, vegetable juices); (2) fruits (apples, pineapples, apricots, bananas, pears, strawberries, peaches, citrus fruit, fruit juices); (3) cereal (bread/pretzels/rolls, cookies/cakes/rusk, rolled oats, muesli, millet, cornmeal/corn starch, wheat semolina/starch, noodles, rice/rice starch, spelt); (4) meat (poultry, lamb, veal/beef, pork, sausages); (5) egg; (6) dairy products (cow milk/cream, yoghurt/quark/cheese); (7) fish; and (8) other (nuts, soy products, cocoa/chocolate).76 85
Finland
Cow’s milk and infant formula; potatoes; carrots; turnip; fruits and berries (as a combined variable); cereals (rye, wheat, oats and barley as a combined variable); other cereals (maize, rice, millet and buckwheat as a combined variable), meat; fish; egg; cabbage; spinach; and lettuce.75 84
UK
21 foods commonly introduced in the first year of life including fruits, vegetables, meat and poultry, grains, egg, and milk products as well at the major food allergens.52 54
China
Six food groups (cereals, vegetables, fruits, meats, fish and eggs) at 6-month interview and 11 food groups (cereals, vegetables, fruits, meats, fish and seafoods, eggs, beans, peanut, other nuts, milk, milk products and sweets).74
Korea
Ten food groups (grains, vegetables, fruits, meat, fish, eggs, dairy, wheat, peanuts and legumes/nuts) where enquired about at 12 months.48
Italy
Nine food groups: vegetables, legumes, or roots (potatoes, carrots, tomatoes and beans), fruits (apples, pears, peaches, apricots, plums, citrus fruits, red fruits), cereals (maize/tapioca, rice, pasta, and gluten-free pasta), meat (poultry, pork, and beef), dairy products (cheese, and other dairies), fish, eggs and nuts/cacao/chocolate.83
Sensitisation
Diet diversity and food allergen sensitisation
IgE sensitisation is a marker of clinical allergy IgE production against a specific food allergen, even though it does not necessarily indicate clinical food allergy. Roduit et al 73 used data from the Protection Against Allergy Study in Rural Environments (PASTURE) study, enrolling children from Austria, Finland, France, Germany and Switzerland. The study data indicated that infants with lower diet diversity, showed an increased risk of sensitisation to food allergens at age 4.5 or 6 years. Nwaru and colleagues84 reported that in a Finnish cohort, reduced diet diversity was associated with an increased risk of food allergen sensitisation. Using data from the FAIR cohort (UK), Maslin et al 54 indicated that higher infant diet diversity, at 6 months of age decreased the odds of food sensitisation by 10 years. In addition, higher infant diet diversity at month 9 reduced the odds of food sensitisation at 2 and 3 years. Finally, increased cumulative infant diet diversity at 6 and 9 months, decreased the odds of food sensitisation at year 1, year 2 and year 3. Data from Korea,48 China74 and Germany85 confirmed that an increased infant diet is associated with reduced food sensitisation throughout childhood.
Diet diversity and aero-allergen sensitisation
Two studies reported on the association between infant diet diversity aero-allergen sensitisation during childhood. The PASTEUR study73 found no association between infant diet diversity and aero-allergen sensitisation at 4.5 and 6 years. A study from Germany85 indicated reduced prevalence of aero-allergen sensitisation up to 15 years with increased infant diet diversity.
Food allergy
Diet diversity
Four observational studies in infancy have investigated the association between infant diet diversity and the development of food allergy throughout childhood. The PASTURE study73 reported a significant association between infants with a more diverse diet and a lower prevalence of childhood reported doctor’s diagnosed food allergy. However,86 diet diversity in the second year of life was not associated with food allergy which may indicate the importance of diet diversity in early life. At 2 years, intake of yoghurt and cow’s milk was associated with reduced food allergy. The FAIR study (UK)52 indicated that increased infant diet diversity at 6 and 9 months was significantly associated with reduced odds of food up to 10 years of age. Food allergy was diagnosed using oral food challenges and/or a good clinical history in combination with food allergen sensitisation. Every additional food introduced by 6 months, reduced the odds of developing food allergy by 10 years with 11%. Using the WHO definition of diet diversity (seven food groups: grains/roots/tubers, legumes/nuts, dairy, flesh foods, eggs, vitamin A rich fruit and vegetables, other fruit and vegetables) by 6 months, a significant reduction in the odds of developing of food allergy by 10 years was seen. For each additional food allergen introduced by 12 months, the odds of food allergy were reduced by 33%. Children were not eating a vast number of foods, a median number of 11 foods (range 0–21), 2 food allergens (range 0–8) and 3 fruit and vegetables (range 0–5) were eaten by 6 months. Children were consuming a median number of five allergens (range 0–8) by 12 months.
A study from China74 compared consumption of 1–5 food groups versus 8–11 food groups. The authors indicated that lower infant food diversity was linked with an increased risk of parent-reported doctor’s diagnosed food allergy by 2 years. Another study from Asia, from a Korean group,48 showed that higher diet diversity based on food group and food allergen consumption and the WHO diversity scores at 3 and 4 months, showed significant association with a reduced risk of developing hen’s egg allergy in the high-risk group, but not in the control group. No associations between the diversity scores at 6 months and food allergy outcomes at 2 years were seen.
Fruit and vegetable diversity
Venter et al 52 reported data from the FAIR study and showed that diversity of fruit and vegetable intake at 6 months and 9 months significantly reduced the odds of FA by 10 years of age.
Food allergen diversity based on randomised controlled trials
The EAT study15 showed that the introduction of food allergens from as early as 3 months in a general breastfed population cohort led to significant risk reductions in food allergy to egg and peanut, in the per-protocol analysis. Due to the intake of several food allergens, the EAT study could potentially be considered as a study on allergen diversity but data on allergen diversity in the control versus active group have not been reported.15
Quake et al 53 performed and randomised controlled trial, feeding infants single food allergens (milk, egg or peanut as 300 mg protein per day: 2100 mg protein/food allergen/week) or two food allergens (milk and egg, egg and peanut, milk and peanut as 300 mg per mix per day: 1050 mg protein/food allergen/week) or a multiple food allergen mix of 10 food allergens (milk, egg, peanut, cashew, almond, shrimp, walnut, wheat, salmon and hazelnut at low (300 mg per day: 21 (3 mg×7) mg/food allergen/week), medium (63 (9 mg×7) mg/food allergen/week) or high doses (210 (30 mg×7) mg/food allergen/week)) versus no allergen introduction in infants age 4–6 months. All infants were breast fed until entering the study. The percentage of children who were able to consume 8 g of total allergen intake in all the groups consuming a mixture of food allergens was significantly higher compared with the control group (q<0.01).
Diet diversity and atopic dermatitis
Eight birth cohorts and one matched case–control study,48 73 75–81 83 85 from Korea, Germany, Italy, New Zealand, Finland, Austria, France and Switzerland studied associations between infant diet diversity and childhood atopic dermatitis/eczema. The combined data from the GINIPlus and LISA studies indicated that higher diet diversity before 4 months was associated with an increased risk of atopic dermatitis at 2 and 6 years, but not at 4 years.76 The LISA plus study only reported an increased risk of atopic dermatitis at the age of 2 years with reduced infant diet diversity at 4 months.80 81 There was no reported association between infant diet diversity at 4 months and atopic dermatitis at 6 years.80 81 Using extremes of intake, data from the LISAplus birth cohort showed that 15-year-old children who had infant diet diversity in the highest quartile showed lower odds of developing atopic dermatitis than children in the lowest quartile of infant diet diversity.85 Highlighting concerns about increased diet diversity before 4 months, data from a New Zealand indicated that an increased infant diet diversity during the first 4 months of life was associated with an increased risk of developing atopic dermatitis at 2 and 3 years and an increased risk of recurrent atopic dermatitis at 10 years.77–79 Nwaru et al 75 (Finland) reported that reduced diet diversity at 6 and 12 months showed an association with an increased risk of atopic dermatitis at 5 years.75 The PASTURE study from Europe showed that increased infant diet diversity was associated with a reduced risk of atopic dermatitis for up to 4 years.82 A Chinese study indicated a reduced prevalence of skin allergies in children (up to 2 years of age) with higher diet diversity by 6 and 12 months.74 A case–control study from Italy indicated that a more diverse diet at 4 and 5 months was associated with a reduced risk of atopic dermatitis by 2 years of age.83
Diet diversity and asthma and allergic rhinitis
Three cohorts including two large European birth cohorts the PASTURE study73; and the Finnish Type I Diabetes Prediction and Prevention Study Prospective Cohort Study75 and a Chinese cohort investigated the relationship between infant diet diversity and childhood asthma and allergic rhinitis.74 Roduit et al 73 reported that increased infant diet diversity was associated with a reduced risk of the development of reported asthma in the PASTEUR study. They noted a 26% reduction in asthma with the introduction of each additional food. In this study, no association between infant diet diversity and childhood allergic rhinitis was noted. Nwaru et al 75 reported that reduced diet diversity at 12 months of life was associated with an increased risk of wheeze and asthma at 5 years of age, in the Finnish Type I Diabetes Prediction and Prevention Study. Reduced infant diet diversity at 6 and 12 months was significantly associated with and increased risk of developing allergic rhinitis at 4 years. A study from China reported a reduced prevalence of respiratory allergies up to 2 years in children with higher infant diet diversity by 6 and 12 months.74
In summary, most studies indicate that higher infant diet diversity was associated with reduced allergy outcomes during childhood. A note of caution is the reported association between higher infant diet diversity before 4 months and increased allergy outcomes during later childhood.
Diet indices in infancy and allergy outcomes
There are currently no studies investigating infant diet indices or food patterns and childhood allergy outcomes.
Key measurement issues to address when designing studies assessing the association between diet diversity and diet indices and allergy outcomes
The diet diversity measures in the infant studies mentioned, differed to some extent. Most studies counted the number of food groups consumed. One study counted a number of foods consumed.52 54 The number of foods and food groups counted ranged from around eight food groups (48 foods grouped into 8 groups)76 85 to 21 foods.52 54 One only study in infants counted ‘less healthy’ food in infancy as part of their diet diversity.7 Venter et al 69 showed in their study focusing on the maternal diet during pregnancy, that this may be an important dietary factor to study. All other studies in infants only enquired about healthy foods in their diet diversity scores. Diet diversity measures either based on food groups or foods (other than fruit and vegetable diversity), included food allergens. The differences in diet diversity measures and the fact that allergen intake was included may have influenced outcomes. However, Venter et al 52 54 showed that any form of diversity either foods, food groups, food allergens or fruit and vegetables was associated with reduced food allergies which may indicate that any form or increased food intake, may be associated with reduced food allergy outcomes, but this has not been studied for other allergy outcomes in childhood.
Dietary intake methodologies can be improved in future studies by including information on portion sizes, frequency of consumption, if foods are considered healthy, methods of food preparation, if the food was fortified, including complex dishes in diversity analysis, using validated diet instruments, obtaining information on breast and formula feeding and age when solid foods were introduced.32 Outcomes measures should ideally use validated tools, but a physician diagnosis of atopic dermatitis, asthma, allergic rhinitis and the use of an oral food challenge to diagnose food allergy is preferred. Mechanistic studies are required to understand intervention effects and could include the microbiome, immunological indices and epigenetic outcomes.
Practical pointers
There are many ways in which diet diversity and diet quality as measure with diet indices in the first year of life can be improved (figure 1). This can be done by focusing on varying the types of food within each food group, for example, berries, cherries, apples and bananas opposed to feeding just one type of fruit. The American Academy of Pediatrics stated in 2019 that it is no longer required to wait 3–5 days between each new foods and that it is now acceptable to start with more than one food at a time.87 This will increase diet diversity and quality and has been reported to reduce picky eating behaviour in toddlers.88 The joint American Academy of Allergy, Asthma and Immunology, Canadian Society of Allergy and Clinical Immunology and the American College of Allergy, Asthma and Immunology consensus statement89 also support a diverse diet for the prevention of food allergy in young children.
Diet diversity plan. It provides a diet diversity plan for an infant 7–9 months providing 35 plant-based food, 6 food allergens and protein sources from fish, poultry, beef, pork, lentils, beans per week.
Conclusion
Diet diversity and indices are useful to describe food intake of infants and young children. Diet diversity in infancy and pregnancy, focusing on healthy foods, could lead to reduced offspring allergy outcomes. Allergen diversity, as part of overall diet diversity, in infancy may also lead to reduced childhood food allergies. Diet quality in pregnancy, may be an important contributor to allergy prevention but there are no data on diet quality in breast feeding and early life. There is a need to harmonise study methods for studying dietary intake, allergy outcomes and underlying mechanisms. The lack of any randomised controlled trials in this field has been clearly demonstrated. Diet instructions to increase diet diversity and quality from conception to early childhood may play an important role in allergy prevention.
Data availability statement
Data sharing not applicable as no datasets generated and/or analysed for this study.
Ethics statements
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Not applicable.
References
Footnotes
Twitter @VenterCarina
Contributors CV is the sole author of the paper. She performed the literature searches and compiled the paper.
Funding The author has not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests CV reports grants from Reckitt Benckiser, and personal fees from Reckitt, Nestle Nutrition Institute, Danone, Abbott Nutrition and HAL Allergy outside the submitted work.
Provenance and peer review Not commissioned; externally peer reviewed. 1. Special Issue - Prevention of Allergies in the post-pandemic Era 2. by Dr. Christophe Dupont, United Kingdom of Great Britain and Northern Ireland.