The search strategy aimed to find both published and
unpublished studies. A three-step search strategy was
utilised in this review. An initial search of Medline
(Table 1), Cochrane Database of Systematic Reviews and
Psychinfo was undertaken, followed by analysis of the
text words contained in the title and abstract, and of the
index terms used to describe the article.

A second search
using all identified keywords and index terms diet was
then undertaken across all included databases. Thirdly,
the reference list of all identified articles was searched
for additional studies. No language restriction was applied.
Moreover, food industries and consumer associations
were contacted to know if they were aware of
unpublished studies.
Types of studies were broad and unrestrictive to
capture as much data as possible. Meta-analysis, randomised
controlled, quasi experimental, cohort, casecontrol
and cross-sectional studies were accepted. In
vitro, ex vivo, and animals studies have been excluded.
Whatever its design and quality, a single study is never
able to establish the causality between the exposure and
the disease, in this case between IS consumption and its
effects on health. In our review, we used part of Hill’s
criteria of causation to assist in the assessment of the
causal relationships. Indeed, a modified version of the
Bradford Hill criteria was used to evaluate the evidence
of a causal relationship between IS consumption and
health outcomes. As a matter of fact, the following eight
criteria, considered as the most important to answer our
questions, were used in our review: strength, consistency,
temporality, coherence, experiment, plausibility, analogy
and biological gradient. One criterion, the specificity, was
omitted because considered as nonspecific to our various
outcomes. It should be pointed that none of these criteria
alone is sufficient to establish causality and that no systematic
algorithm was used. The final interpretation of the
causality was based on experts’ judgment based on all analysed
data.
Results
The exhaustive review included 10,989 manuscripts
(9,965 in English and 1024 in non-English languages).
Out of them, 9,373 were excluded after a reading of the
title and the abstract. Consequently, 1,616 full-text manuscripts
have been extensively reviewed of which 383 (all
in English) have been considered of interest for the topic
of benefits and risks related to IS. For this review however,
only the most relevant ones have been quoted,
mainly based on their methodology, novelty and originality.
Among these studies, 30.1 % were funded by
the industry, 56.3 % by non-profit organisations, and
the others did not report funding sources. However,
we did not consider differently studies based the
funding source.