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Individuals after SCI commonly experience chronic inflammation (Allison & Ditor, 2015). This prolonged state of elevated inflammation is associated with immune impairment which can lead to infections and other dysfunctions (Allison et al., 2017). Inflammation is measured by serum levels of certain pro-inflammatory cytokines, such as interleukin and interferon gamma (Hayes et al., 2002). Two methods of reducing inflammation are exercise and diet modification however, SCI individuals often have difficulty participating in exercise (Allison et al., 2018). Several supplements have been identified to have anti-inflammatory properties in uninjured individuals (Galland, 2010). These supplements, such as omega-3 and fatty acids, and anti-inflammation dietary changes have not been studied at length in SCI populations. The following studies have been identified and meet inclusion criteria, examining anti-inflammation diet changes and supplements in SCI.

Table 7 Diet and Inflammatory Mediator Effects

Author Year

Country

Research Design

PEDro Score

Sample Size

MethodsOutcomes
Allison et al. 2018

Canada

Secondary Analysis of a previous RCT(Alison et al. 2017)

N=20

Population: Mean age=48.7±14.0 yr; Gender: males=10, females=10; Time since injury=13.1±10.8 yr; Level of injury: C=12, T=6, L=2; Severity of injury: AIS A=7, B=2, C=3, D=8.

Intervention: Participants were randomly assigned to a three-month control group or a three-month anti-inflammatory diet treatment group.

Outcome Measures: Change in nutrient intake, and corresponding changes to various inflammatory mediators (C reactive protein (CRP), interleukin (IL-2, IL-6, IL-1β), tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), prostaglandin E2 (PGE2) and kynurenine/tryptophan ration (KYN/TRP).

*NOTE: This was a statistical analysis of a previous randomized controlled trial (Alison et al. 2017).

1.     No significant change in total energy intake from baseline to the end of the intervention (p=0.10).

2.     Significant reduction in fat intake (p=0.02) and significant increase in protein intake (p=0.02), however carbohydrate intake was not significantly changed (p=0.23).

3.     Well-established anti-inflammatory nutrients vitamin A, carotenoids, vitamin C, vitamin E, and omega-3 fatty acids all showed significant increases from baseline to intervention’s end (p<0.01 for each).

4.     Pro-inflammatory nutrients showed significant reductions from baseline to intervention’s end including trans fatty acids (p=0.05), caffeine (p<0.01) and sodium (p=0.02).

5.     No significant observable changes in total energy intake, macronutrient intake, or nutrients with anti-inflammatory or pro-inflammatory properties in the control group (p>0.05 for all).

6.     Mann-Whitney test showed change scores from baseline – 3-months between treatments group and control group were significantly different for IFN-γ (p=0.01), IL-1β (p=0.01), and I-2 (p=0.01).

7.     No other significant differences reported by the Mann-Whitney test for inflammatory mediators in the treatment or control groups.

8.     Friedman test indicated that in the treatment group there was a statistically significant reduction in IFN-γ (p=0.01), IL-1β (p<0.01) and IL-6 (p<0.05).

9.     No other significant changes reported by the Friedman test for the inflammatory mediators in the treatment or control group.

10.   Wilcoxon signed-rank test reported significant reductions from baseline to 3 months in IFN-γ (p=0.01) and IL-1β (p<0.01) in the treatment group.

11.   No other significant changes reported by the Wilcoxon signed-rank test in the treatment or control group.

12.   Non-significant trends towards group X time interactions for TNF-α (p=0.10) and PGE2 (p=0.07) by two-way repeated measures ANOVA.

13.   No trends observed for KYN/TRP by two-way measured ANOVA.

14.   Change in total caloric intake and individual macronutrient intake was not significantly correlated with any inflammatory mediator.

15.   Significant negative correlation observed between the change in vitamin A and the change in CRP (p=0.02), IL-1β (p=0.02), IFN-γ (p=0.04), and KYN/TRP (p<0.01).

16.   Significant negative correlation observed between the change in carotenoids and the change in CRP (p<0.01), IL-1β (p<0.01), PGE2 (p=0.05) and KYN/TRP (p<0.01).

17.   Significant negative correlation observed between the change in omega-3 and the change in IL-1β (p=0.03) and KYN/TRP (p=0.01).

18.   Significant negative correlation observed between the change in zinc and the change in IL-2 (p=0.04), IL-6 (p=0.05), IL-1β (p<0.01), TNF-α (p=0.02), IFN-γ (p=0.03) and KYN/TRP (p<0.01).

19.   Significant negative correlation observed between the change in vitamin C and the change in the KYN/TRP ratio (p=0.05) as well as the change in iron and the change in the KYN/TRP ratio (p<0.01).

20.   Significant positive correlation observed between the change in iodine and the change in IL-2 (p=0.03), IL-6 (p=0.01) and IFN-γ (p=0.02).

Allison et al. 2017

Canada

RCT

PEDro=7

N=20

Population: Mean age=47.8±13.8 yr; Gender: males=10, females=10; Time since injury=13.1±10.8 yr; Level of injury: C=12, T=6, L=2; Severity of injury: AIS A=7, B=2, C=3, D=8.

Intervention: Participants were randomized into a control group, who ate foods they would normally eat and a treatment group, which eliminated inflammatory inducing foods from their diet and added anti-inflammatory foods. Nerve conduction was tested at baseline, 1 and 3 months.

Outcome Measures: Inflammatory Mediators (pro-inflammatory cytokines (IL-2, IL-1β, IL-6, TNF-α and IFN-ϒ), acute phase protein (CRP), anti-inflammatory cytokines (IL-4, IL-10 and IL-IRA), and pro-inflammatory eicosanoid (PGE2), nerve conduction velocity (NCV), and M-wave amplitude.

1.     Mann-Whitney test showed significant difference between treatment and control groups for IFN-ϒ (p=0.01), IL-1β (p=0.01) and IL-2 (p=0.01).

2.     Friedman test showed a significant reduction over time for the treatment group in IFN-ϒ (p=0.01), IL-1β (p=0.01), and IL-6 (p<0.05).

3.     Mann-Whitney and Friedman tests did not show any significant reductions for an inflammatory mediator in the control group (p>0.05).

4.     Wilcoxon signed-rank test showed significant reduction over time for the treatment group in IFN-ϒ (p=0.01) and IL-1β (p<0.01).

5.     Wilcoxon signed-rank test showed no significant reduction over time at 3 months from baseline in IL-6 (p=0.08) but did at 1 month (p=0.02).

6.     No other significant changes in pro-inflammatory or anti-inflammatory cytokines (p>0.05).

7.     No significant Group X Time interactions observed for motor NCV (p=0.77) or M-wave amplitude (p=0.61).

Effect Sizes: Forest plot of standardized mean differences (SMD ± 95%C.I.) as calculated from pre- and post-intervention data.

Discussion

Allison et al. (2017) conducted an RCT investigating the effects of an anti-inflammatory diet intervention in SCI individuals. The control group individuals continued their normal diets, where the treatment group eliminated inflammation inducing foods such as foods with high glycemic indices (refined wheat and sugar products), food with common intolerances (milk), and unhealthy food such as hydrogenated oils (Allison et al., 2017). The treatment group participants also consumed anti-inflammatory diet supplements (such as omega-3, chlorella, and antioxidants) up to three times a day depending on the supplement and dosage (Allison et al., 2017). The diet intervention program lasted for 12-weeks. The participants completed detailed 7-day diet records at baseline, and 3-day records at one, two, and three month follow-ups. Outcomes included measuring inflammatory serum markers and nerve conduction (Allison et al., 2017). While the authors found significant reduction in inflammation serum markers in the treatment group, there was no significant interaction effect found between-groups over time for motor nerve conduction (Allison et al., 2017). This study highlights a reduction in known inflammatory serum markers in SCI individuals after an anti-inflammatory dietary intervention, but no significant improvement was seen on motor nerve conduction (Allison et al., 2017). The authors followed-up this study with a secondary analysis investigating the changes in nutrient intake and their relationship with different inflammatory serum markers (Allison et al., 2018). The main findings of this secondary analysis indicate that significantly reducing fats and increasing protein intake lead to reductions in inflammatory serum biomarkers, while carbohydrates and caloric restriction have no effect. When looking at supplements, vitamins A, carotenoids, zinc, and omega-3 were associated with a reduction in serum biomarkers indicating inflammation (Allison et al., 2018). The authors discuss similarities of their diet intervention to the ‘Mediterranean diet’ which has been studied in healthy controls. The Mediterranean diet consists of lowering excess sugar, and red and processed meats, emphasizing ingestion of olive oil, fresh fruits and vegetables, fish and white meats (Estruch et al., 2013). The authors highlight a need for more studies to be conducted with anti-inflammatory diet changes in SCI individuals to better understand the potential benefits.

Conclusion

There is level 1b evidence (from one RCT and one secondary RCT analysis; Allison et al., 2017;2018) that a diet intervention focusing on anti-inflammatory diet changes and supplements can reduce inflammatory serum markers, but did not show improvement in motor nerve conduction compared to a control group.

  • A diet intervention focusing on anti-inflammatory foods and supplements can reduce inflammation serum markers, but may not show improvement in motor nerve conduction.