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Sports Foods and Supplements for Athletics 207

a doseof 0.2–0.4g/kgBM) achieves anacute (Castell et al., 2019; Peake et al., 2017), and a high incidence of
increaseinextracellular/ blood buffering (Carr et al., 2011a) with upper respiratory tract illness is frequently reported (Drew et al.,
peak blood bicarbonate levels occurring after 75–180 min (when 2018; Nieman, 1994), before and particularly after endurance
consuming 0.3 g/kg BM NaHCO3), which appear to decrease by events. Low-energy availability has been identified as a key
3-hr postsupplementation nutritional factor in such illness (Drew et al., 2018; Heikura et al.,
(Jones et al., 2016b). 2018); however, the provision of nutritional supplements to
However, split doses (i.e., alleviate exercise-induced immunodepression and to aid more
several smaller doses) rapid recovery in athletes has also been well studied. Sometimes
taken over a 30- to 60- certain supplements initially appear promising, but further
min time period intensive investigation fails to provide sufficient evidence of
(Krustrup et al., 2015) or consistent beneficial effects on some aspects of exercise-induced
serial loading with three immunodepression. As different nutritional supplements become
to four smaller doses per unfashionable, whether targeting immunodepression or
day for two to four performance, others take their place; however, the pros and cons
consecutive days prior to of these need to be carefully studied. For instance, probiotic
an event (Burke, 2013) supplementation has been investigated in recent years (as have
has been proposed as prebiotics), with preliminary evidence of positive effects on
methods to overcome the immune function (Cox et al., 2010) that might support the
well-established consistency of training and competition. However, the effects of
gastrointestinal distress such supplementation are dependent on appropriate doses of live
associated with this bacteria of specific strains (e.g., Lactobacillus, Bifidobacterium),
supplement. Further strategies used to minimize gastrointestinal and larger studies are still needed to provide definitive evidence
distress include the coingestion of NaHCO3 with a small that probiotics benefit the immune function of athletes.
carbohydrate-rich meal (∼ 1.5 g/kg BM CHO; Carr et al., 2011b) Glutamine and branched chain amino acids, which are often
or the use of the less effective but more gut-friendly sodium marketed to support bodybuilding and postexercise recovery, also
citrate as an alternative (Requena et al., 2005). have an unclear role in supporting immune function in athletes
In summary, despite the relatively robust evidence base to (Bermon et al., 2017). Clearly, immunonutrition is an emerging
support the consideration for use of these five supplements by and important area for consideration in the use of dietary
welltrained athlete populations, the potential side effects and supplements for athlete populations, and as such, the reader is
negative individual tolerance must be considered, and therefore, directed to recent reviews in this area (Bermon et al., 2017;
any supplement use should be thoroughly trialed in training Castell et al., 2019), in addition to the comprehensive paper on
before competition. Notwithstanding, as can be seen in Table 2, feeding the immune system (Calder, 2013).
there are potential challenges for the use of these supplements With respect to the inflammatory response, there is a
within track-and-field events, including issues of repeated use growing body of work that is investigating anti-inflammatory and
and the potential for interaction when several potentially useful antioxidant aspects of various foods and supplements. For
supplements are used together (Burke, 2017). The current instance, food polyphenols possess strong antioxidant and anti-
literature relevant to such use is not well understood and requires inflammatory properties (Tsao, 2010) that may be beneficial to
more research. exercise recovery. Specifically, the high-anthocyanin content of
tart Montmorency cherries is proposed to reduce the
inflammatory
Therapeutic Nutritional Supplements and and oxidative
stress
Prophylactic Aids responses to
strenuous
In the context of this review, “therapeutic/prophylactic
supplements” are considered as nutritional aids that can be used exercise, such
as a marathon
either to (a) correct a deficiency, (b) assist in the possible (Dimitriou et
prevention of illness and/or injury, or (c) help in the recovery al., 2015;
from the stress of physical workloads via an anti-inflammatory Howatson et
effect. For instance, it is well known that iron deficiency can al., 2010), or
impair hematologic adaptation, which left untreated can consecutive
negatively impact on athletic performance (Garvican et al., 2011). days of
However, nutritional correction of this issue via various intermittent
intervention strategies has been regularly shown to have a high-intensity activity (Bell et al., 2014). This may be particularly
positive impact on correcting the underlying deficiency and relevant to the heavy training loads of many high-performance
enhancing athlete performance (Dawson et al., 2006; Garvican et athletes, as well as the competition recovery in multievents in
al., 2011; Woods et al., 2014). track-and-field athletics or the programs of middledistance
Regarding illness, there is strong evidence to suggest that runners with heats and finals across several events at major
immunodepression can occur as a result of strenuous exercise
IJSNEM Vol. 29, No. 2, 2019
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