A randomized controlled trial of 25 recreationally trained adults found that six weeks of intense functional training improved strength by 3-6% and workout duration, but a supplement containing fish protein, vitamin D, and omega-3 fatty acids provided no additional benefits compared to regular protein or placebo. According to Gram Research analysis, for people already eating adequate protein and nutrients, expensive multi-ingredient supplements don’t enhance exercise performance.
A new study tested whether a special supplement containing fish protein, vitamin D, and omega-3 fatty acids could help people get stronger and build more endurance during intense workouts. Twenty-five recreationally trained adults took the supplement for 6 weeks while doing high-intensity functional training three times per week. While the training itself made people stronger and improved their workout performance by 3-6%, the supplement didn’t add any extra benefits compared to regular protein or a placebo. According to Gram Research analysis, this suggests that for people already eating enough protein and nutrients, expensive multi-ingredient supplements may not provide additional performance gains.
Key Statistics
A randomized controlled trial of 25 recreationally trained adults (14 women, 11 men) found that six weeks of high-intensity functional training increased one-repetition maximum strength by 3-6% in shoulder press exercises, with no additional benefit from fish protein, vitamin D, and omega-3 supplementation compared to placebo.
Research published in the European Journal of Nutrition in 2026 showed that workout duration per training session increased significantly with six weeks of high-intensity functional training, but supplementation with fish protein, vitamin D, and omega-3 fatty acids did not enhance this adaptation compared to whey protein or placebo.
A 2026 crossover trial found that core muscle strength endurance improved by similar amounts across all three supplement conditions (fish-based supplement, whey protein, and placebo) during six weeks of high-intensity functional training, indicating supplementation type did not influence training adaptations.
According to a 2026 randomized controlled trial of 25 recreationally trained participants, all three supplement groups—fish protein with vitamin D and omega-3s, whey protein, and placebo—showed identical improvements in strength and endurance measures, suggesting that adequate baseline nutrition matters more than supplement composition.
The Quick Take
- What they studied: Whether a supplement containing fish protein, vitamin D, and omega-3 fatty acids could improve strength and endurance during intense exercise workouts.
- Who participated: Twenty-five recreationally trained adults (14 women and 11 men) who already exercised regularly. They weren’t professional athletes, but they had some fitness experience.
- Key finding: Six weeks of intense training improved strength by 3-6% and workout duration, but the special supplement provided no additional benefit compared to regular protein powder or a placebo.
- What it means for you: If you’re already eating enough protein and getting basic nutrients, spending extra money on fancy multi-ingredient supplements probably won’t make you stronger or more fit. The training itself is what matters most.
The Research Details
This was a carefully controlled experiment where 25 people did the same intense workouts three times per week for 6 weeks. The clever part: each person tried three different supplements in rotation, with 2-week breaks between each one. This “crossover” design means each person served as their own comparison group, which makes the results more reliable.
The three supplements were: (1) a special mix with fish protein, vitamin D, and omega-3 fatty acids, (2) regular whey protein powder, and (3) a placebo (fake supplement with no active ingredients). Everyone ate the same amount of total calories and protein daily, so the only difference was the supplement type.
Researchers measured strength (how much weight people could lift), endurance (how long they could exercise), and workout performance at the beginning and end of each 6-week period. They used statistical tests to see if the supplements made any real difference.
This research design is strong because each person tried all three supplements, eliminating differences between individuals. The researchers also didn’t know which supplement was which (blinded design), preventing bias. However, the small group size (25 people) means results might not apply to everyone.
Strengths: This was a well-designed randomized controlled trial with blinding and a crossover design that controls for individual differences. The study was registered before it started (good practice). Limitations: Only 25 participants is relatively small, so results may not apply to larger populations. The study only lasted 6 weeks, so we don’t know about longer-term effects. Participants were recreationally trained, so results may differ for beginners or elite athletes.
What the Results Show
The intense training program itself worked. Over 6 weeks, participants increased their one-repetition maximum (the heaviest weight they could lift once) by 3-6% in shoulder press exercises. Their core muscle strength endurance also improved significantly. Workout duration per training session increased, meaning people could exercise longer as they got fitter.
However, the special supplement containing fish protein, vitamin D, and omega-3 fatty acids made no difference compared to regular whey protein or the placebo. All three supplement groups showed the same improvements from training. This was true for every measure tested: strength gains, endurance improvements, and workout duration.
The results were consistent and clear: supplementation did not enhance any of the training adaptations measured. Whether someone took the fancy fish-based supplement, regular whey protein, or a placebo, their strength and endurance improvements were identical.
The study found that all participants improved their maximal force production in shoulder press exercises by similar amounts across all three supplement conditions. Core muscle strength endurance showed consistent improvements regardless of supplement type. Workout duration per session increased with training, but again, supplement type didn’t matter. These consistent null findings across multiple performance measures strengthen the conclusion that the supplement provided no added benefit.
Previous research on multi-ingredient supplements during intense training has shown mixed results, with some studies suggesting benefits and others finding none. This study adds to growing evidence that for people already consuming adequate protein and nutrients, additional supplementation may not provide extra performance gains. The findings align with recent meta-analyses suggesting that basic nutritional adequacy matters more than expensive supplement combinations.
The study only included 25 people, which is a small sample size. Results might be different with more participants or different types of people (beginners, elite athletes, older adults). The study lasted only 6 weeks, so we don’t know if longer-term supplementation might eventually show benefits. All participants were recreationally trained, so results may not apply to sedentary people or professional athletes. The study didn’t measure some outcomes like muscle size or body composition changes that might respond differently to supplements.
The Bottom Line
For recreationally trained people eating adequate protein and nutrients: save your money on expensive multi-ingredient supplements. Focus on consistent training, adequate total protein intake (about 1.6-2.2 grams per kilogram of body weight daily), and basic nutrition. If you’re deficient in specific nutrients, address that through food or targeted supplementation, but fancy combinations don’t appear to enhance performance. Confidence level: Moderate (based on one well-designed study with a small sample).
This applies to recreationally trained people who already exercise regularly and eat reasonably well. It may not apply to people with specific nutrient deficiencies, elite athletes with extreme training demands, or people just starting an exercise program. If you have a diagnosed vitamin D deficiency or omega-3 deficiency, that’s different from taking supplements as a performance enhancer.
The training itself showed improvements within 6 weeks. However, if you stop taking the supplement, you won’t lose the strength gains you made from training—those come from the exercise itself, not the supplement.
Frequently Asked Questions
Does fish oil and vitamin D supplement help you get stronger from working out?
A 2026 study of 25 trained adults found that a supplement with fish protein, vitamin D, and omega-3s provided no additional strength gains compared to regular protein powder or placebo during six weeks of intense training. The training itself improved strength 3-6%, but the supplement didn’t add extra benefits.
Should I take omega-3 supplements if I do CrossFit or functional fitness training?
Research suggests that for people already eating adequate protein and nutrients, omega-3 supplements don’t enhance performance during intense training. If you have a diagnosed omega-3 deficiency, that’s different. Otherwise, focus on consistent training and adequate overall nutrition rather than expensive supplements.
What supplement should I take to get stronger faster?
This study found that supplement type didn’t matter—training consistency did. All groups improved equally whether taking fish-based supplements, whey protein, or placebo. The most important factors are doing the training three times per week and eating enough total protein (about 1.6-2.2 grams per kilogram of body weight daily).
Is it worth buying expensive multi-ingredient supplements for fitness?
For recreationally trained people eating adequately, probably not. This 2026 trial found that a fancy multi-ingredient supplement provided no advantage over basic whey protein or placebo. Save money by focusing on consistent training and meeting your basic nutritional needs through food.
How long does it take to see strength improvements from training?
This study showed measurable strength improvements within six weeks of training three times per week. However, these gains came from the training itself, not from supplements. Consistency matters more than supplement type.
Want to Apply This Research?
- Track your one-repetition maximum (heaviest single lift) in key exercises weekly, and monitor total daily protein intake in grams. Compare these metrics across 6-week training blocks to see if your improvements come from consistent training rather than supplement changes.
- Instead of buying expensive supplements, use the app to log your daily protein intake from food sources and ensure you’re hitting 1.6-2.2 grams per kilogram of body weight. Track your workout consistency (3+ sessions per week) as the primary driver of strength gains.
- Create a 6-week training cycle in the app where you measure strength (one-rep max) and workout duration weekly. Compare results across different supplement conditions or no supplementation to see if your personal data matches this study’s findings.
This research applies to recreationally trained healthy adults and may not apply to people with nutrient deficiencies, medical conditions, or those taking medications. If you have a diagnosed vitamin D or omega-3 deficiency, consult your healthcare provider about appropriate treatment. This study does not replace personalized medical advice. Always consult with a healthcare provider or registered dietitian before starting new supplements, especially if you have underlying health conditions or take medications. The findings represent one study and should be considered alongside other research and individual circumstances.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.