Mixed
Supplementation with fish protein, vitamin D, and omega-3 fatty acids provides no additional benefit to physical performance adaptations (strength, endurance, workout duration) compared to whey protein or maltodextrin during a 6-week high-intensity functional training (HIFT) program in recreationally trained individuals.
If you are doing high-intensity functional training (like CrossFit), switching to a complex supplement with fish protein, vitamin D, and omega-3s will not give you better strength or endurance gains than taking whey protein or even just carbohydrates (maltodextrin), provided your overall diet is adequate. Focus on consistent training and basic protein intake rather than expensive multi-ingredient stacks for performance enhancement.
Supplementation did not affect any of these adaptations. ... increasing the intake of protein, vitamin D, and ω3 fatty acids did not influence the variables assessed.
Why this rating
Randomized, triple-crossover, counterbalanced, researcher-blinded design with adequate sample size for the effect size, though limited by dropouts and short duration.
Source
Effects of a nutritional supplement containing fish protein, vitamin D, and ω3 fatty acids, taken during high-intensity functional training, on physical performance in recreationally trained individuals: a randomized controlled trial
Ioannis Kosmidis et al. · European Journal of Nutrition · 2026
DOI 10.1007/s00394-026-03983-z
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