Abstract
Anti-inflammatory agents such as long-chain ω-3 fatty acids have been recognized to improve disease-related fatigue. We hypothesized that α-linolenic acid may also benefit in reduction of fatigue in low-grade inflammation such as overweight/obesity. Seventy two healthy children and adolescents with body mass index (BMI) >25 kg/m2 were randomized to flaxseed (n=38) and puffed wheat (n=34) groups. Participants consumed isocaloric amounts of either 20 g/day flaxseed or 25 g/day puffed wheat for 4 weeks. Fatigue, mood feelings (depression, anxiety, and stress), appetite, energy intake, weight, height, and waist circumference were measured. Analysis was performed based on per-protocol (PP) and intention-to-treat (ITT) approaches. Consumption of flaxseed decreased mental fatigue and caused a significant between-group difference (P<0.001). Although no significant change in physical and total score of fatigue was observed in either group, a significant between-group difference occurred due to a more remarkable change in these parameters in flaxseed group. General fatigue, motivation, activity, and mood feelings did not change significantly between groups. Flaxseed showed less benefit than puffed wheat on anthropometric measures as it caused smaller increase in height (0.53±0.89 vs. 1.09±0.87, P=0.03) and reduction in BMI (-0.25±0.63 vs. -0.67±0.56, P=0.01) than puffed wheat. Appetite and waist circumference decreased in both groups but no significant difference was observed between groups. In ITT analysis, only alteration in mental fatigue was significant. In conclusion, consumption of flaxseed may improve mental fatigue in children with overweight/obesity. However, because of smaller increase in height it is better to hinder administration of flaxseed in growth ages.
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Key Points
Fatigue is extreme tiredness resulted from physical and mental exertion. Fatigue is very frequent in educational environments. A study in Poland found that fatigue symptoms in school and university students were as frequent as that in hard-working adults. Fatigue and depression are interrelated as both are associated with increased inflammation. Fatigue and depression are common in patients with autoimmune disorders, and treatment of inflammation may improve their depression and fatigue condition. In the current study, the effect of flaxseed on fatigue, mood, appetite, energy intake, weight and other anthropometric measures in children and adolescents with overweight and obesity were assessed.
A number of clinical trials have reported beneficial effects of ω-3 fatty acids on fatigue. Here it was hypothesized that conditions with low-grade inflammation such as overweight and obesity may also benefit from fatigue-lowering effect of ω-3 fatty acids. it would be worthwhile to find out if α-linolenic acid has also potential to attenuate fatigue.
During the 4-week trial, consumption of 20 g/day flaxseed improved mental fatigue without affecting general fatigue, motivation, and activity as well as psychological feelings such as depression and anxiety. Although no significant change in physical fatigue was observed in either group, a significant difference was observed between groups in favor of flaxseed. Nevertheless, flaxseed showed less benefit than puffed wheat for anthropometric measures as it caused smaller increase in height and reduction in BMI than puffed wheat. Appetite decreased to the same extent in both groups.
Both treatments suppressed appetite; although the suppression was significant in both groups no difference was observed between groups. Based on data of nutritional values, flaxseed and puffed wheat have almost equal amounts of protein (3.7 g vs. 3.8 g in the consumed flaxseed and puffed wheat, respectively) but flaxseed has more fiber than puffed wheat (5.5 g vs. 2.8 g). Thus, flaxseed would be expected to confer stronger effect for appetite suppression than puffed wheat. However, appetite was suppressed to the same extent in flaxseed and puffed wheat group
In conclusion, consumption of 20 g/day flaxseed attenuated mental fatigue of children and adolescents with overweight/obesity. However, the effect size was small and the improvement was not observed in other aspects of fatigue. According to the baseline values, the participants had mostly very low to low fatigue. Therefore, it is likely that a floor effect has occurred in which the magnitude of the effects has been small due to low baseline fatigue while better results can be achieved if participants with more severe fatigue are recruited. The lack of effect on mood feelings including depression, anxiety, and stress should be considered with caution as the participants were not patients with mood disorders.