Summary and Concluding Remarks
In summary, fibers are essential components of a healthy diet with
multiple health benefits, and fiber intake has decreased at the same
time as allergy rates have increased. There are a wide variety of fiber
types, and specific fibers may contribute to maintaining a tolerogenic
mucosal environment and may protect against allergic disorders. However,
the optimal prevention or treatment strategies involving fibers in
humans have yet to be defined. One mechanism by which fiber impacts the
immune system is dependent on microbial fermentation and secretion of
bioactive metabolites. Thus, fiber supplementation alone may not be
sufficient and simultaneous replacement of missing microbes may be
required for optimal benefits to be observed. Given the varied
functional properties of different fiber types, it is unlikely that one
type of fiber will provide all immune-relevant signals, and regular
consumption of diverse fiber types may be superior to supplementation
with individual fibers, which is consistent with our previous
recommendations regarding the importance of dietary diversity in general
for allergy prevention.60 However, as our
understanding progresses on the role and mechanisms mediating specific
fiber-microbiota-immune interactions, there is significant potential for
using fiber in targeted manipulations of the gut microbiome and its
metabolic functions in promoting immune health. We suggest that the
current classification of different dietary fiber types would benefit by
being updated to include their specific immune functional properties.
Overall, fiber diversity may be more important immunologically than any
single individual fiber type.
We also need to be aware of potentially inconsistent fiber effects
across different disease endotypes, which depends on the distinct
pathophysiological mechanisms in operation for the given endotype. This
is of particular importance in studying heterogeneous diseases like
allergic diseases and asthma and highlight the need for sufficiently
powered studies. Deciphering the molecular alphabet that underpins this
cellular dialogue is a significant challenge, but one that once overcome
will yield the critical insights needed to prevent and treat allergic
disorders in the 21st century. Future research on
fiber-microbe-host interactions should be strongly encouraged as these
discoveries will provide fundamental knowledge on the molecular
communication networks that underpin life as a multicellular
metacommunity and will progress our appreciation for the principle of
biological diversity as a driver of physiological resilience and immune
tolerance.
Conflict of interest Dr. Venter reports personal fees from Danone,
personal fees from NNI, personal fees from Abbot, grants and personal
fees from Reckitt, grants from Peanut board, personal fees from Before
brands, personal fees from Else nutrition, personal fees from Sifter,
outside the submitted work; BVB reports personal fees from Marfo Food
Group, Lelystad, The Netherlands, personal fees from Abbott, grants from
Nutricia Research, outside the submitted work; RM reports other from
Nestle, grants and personal fees from Nutricia/Danone, personal fees
from Mead Johnson, personal fees and other from Abbott, outside the
submitted work. LOM received research grants from GSK and Chiesi,
speaker support from Nestle, Nutricia, Reckitt and Abbott, consultant to
Precision Biotics. CA received Research grants from Allergopharma,
Idorsia, Swiss National Science Foundation, Christine Kühne-Center for
Allergy Research and Education, European Commission’s Horison’s 2020
Framework Programme “CURE”, Novartis Research Institutes and Astra
Zeneca. Took part in the advisory board and received research grants
from Glaxo Smith-Kline, Sanofi/Regeneron, Scibase, Novartis. He is
the Editor-in-Chief of Allergy. Dr. Pali-Schöll reports personal fees
from Bencard Allergie GmbH outside the submitted work. Peter Smith
declares that he has been paid an honorarium for working on the Nestle
Nutrtiion Insitute advisory board. He also has received honorarium
and/or speakers fees for Viatris, GSK, AZ, Sanofi, Mundipharama,
Nutricia. He also has researcher initiated funding from Viatris, GSK and
Sanofi. Dr. Agache is Associate Editor Allergy and Clinical and
Translational allergy. Dr. Greenhawt is a consultant for Aquestive; is a
member of physician/medical advisory boards for DBV Technologies,
Sanofi/Regeneron, Genentech, Nutricia, Novartis, Acquestive, Allergy
Therapeutics, ALK-Abello, AstraZeneca, Allergenis, and Prota; is a
member of the scientific advisory council for the National Peanut Board;
is a member of the Brighton Collaboration Criteria Vaccine Anaphylaxis
2.0 working group; is the senior associate editor for the Annals of
Allergy, Asthma, and Immunology, and is member of the Joint Taskforce on
Allergy Practice Parameters. He has received honorarium for lectures
from ImSci, MedLearningGroup, the Allergy and Asthma Foundation of
America, The Intermountain West Allergy Society, the Wisconsin Allergy
Society, the Los Angeles Society of Allergy and Immunology, the Northern
Califorina Society for Allergy and Immunology, and the Candian Society
for Allergy and Clinical Immunology. IM reports personal fees from
ALK-Abello, personal fees from Beiersdorf Dermo Medical GmbH, personal
fees from Nestlé Deutschland GmbH, personal fees from Nutricia Milupa
GmbH, personal fees from Sanomega GmbH, outside the submitted work; MS
reports grants from Swiss National Science Foundation, grants from GSK,
outside the submitted work. The other authors have not conflict to
declare (CR, CA, KA-P, JW, MF, BN, LJ, KG, EU, KH-S, EV).