Dietary Supplements: What the Science Says

The Foundation First

Supplements are exactly that: supplements. No pill replaces a balanced diet, adequate sleep, and regular exercise.

A systematic review by Blumberg et al. (2017) emphasises: dietary supplements should fill gaps, not serve as a primary source of nutrients.

Category A: Well-Researched, Evidence-Based

Vitamin D

Evidence: A meta-analysis by Autier et al. (2017) analysed 290 studies. Vitamin D supplementation reduces the risk of respiratory infections and improves muscle strength in people with deficiency.

Need in Switzerland: The FOPH estimates that 50-60% of the population has suboptimal vitamin D levels during winter.

Dosage: 1000-2000 IU daily. For severe deficiency (blood test recommended), higher doses may be needed short-term under medical supervision.

Creatine

Evidence: Creatine is one of the most thoroughly researched supplements in existence. A meta-analysis by Rawson & Volek (2003) in the Journal of Strength and Conditioning Research found:

• Strength increase: +8% compared to placebo
• Muscle mass: +0.36kg per week of training

The ISSN Position Stand (Kreider et al., 2017) confirms its safety even with long-term use.

Dosage: 3-5g of creatine monohydrate daily. A loading phase is not necessary.

Myth: Creatine does not cause hair loss. The only study suggesting this (van der Merwe, 2009) had methodological weaknesses and could not be replicated.

Omega-3 Fatty Acids (EPA/DHA)

Evidence: A Cochrane Review by Abdelhamid et al. (2018) analysed 79 studies. Omega-3 supplementation reduces triglycerides and likely has positive effects on cardiovascular health.

For whom: Individuals with low fish consumption (<2 portions of fatty fish per week).

Dosage: 1-2g EPA+DHA daily. Pay attention to quality (avoid oxidation).

Protein Powder

Evidence: A meta-analysis by Morton et al. (2018) confirms that protein supplementation combined with resistance training significantly increases muscle mass and strength.

For whom: Individuals who struggle to meet their protein requirements (1.6-2.2g/kg) through regular meals alone.

What to look for:

• Minimal additives
• No artificial sweeteners
• For plant-based proteins: combination of different sources

Caffeine

Evidence: A meta-analysis by Grgic et al. (2020) found significant improvements in strength, endurance, and performance from caffeine supplementation.

Dosage: 3-6mg/kg body weight, 30-60 minutes before training.

Limitation: Tolerance develops with daily use. Regular breaks can maintain its effectiveness.

Category B: Situational

Vitamin B12

For whom: Vegans (essential), vegetarians (recommended), older adults (absorption decreases with age).

Evidence: B12 deficiency can lead to irreversible neurological damage. With a plant-based diet, supplementation is not optional.

Iron

Important: Only supplement with confirmed deficiency. Excess iron can cause oxidative stress (Galaris et al., 2019).

For whom: Menstruating women, endurance athletes, vegetarians/vegans — after a blood test.

Magnesium

Evidence: A systematic review by Boyle et al. (2017) found moderate evidence for magnesium’s role in addressing sleep problems.

For whom: Physically active individuals (increased demand), people with stress or sleep issues.

Dosage: 200-400mg daily, preferably in the evening. Citrate or glycinate are better absorbed than oxide.

Category C: Overhyped or Not Evidence-Based

BCAAs

Reality: If you eat enough protein, isolated BCAAs provide no additional benefit. A meta-analysis by Wolfe (2017) confirms that complete protein sources are superior to BCAAs.

”Fat Burners”

Reality: Most fat burners primarily contain caffeine. The advertised “thermogenic” effects of other ingredients are minimal to non-existent in studies.

Testosterone Boosters

Reality: No legal supplement significantly raises testosterone in healthy individuals with normal levels. Studies on tribulus, D-aspartic acid, and similar substances show no clinically relevant effects (Qureshi et al., 2014).

Collagen Peptides

Reality: The evidence is mixed. Collagen is broken down into amino acids in the digestive tract. Some studies show positive effects on skin and joints, but study quality is often limited.

Multivitamins

Reality: A large study (Physicians’ Health Study II) found no benefit from multivitamins for the prevention of cardiovascular disease or cancer in well-nourished adults (Sesso et al., 2012).

Targeted individual supplements for confirmed deficiencies are more effective.

Quality Indicators

Look for:

• Transparent dosage information
• Independent quality certificates (e.g. Informed Sport, NSF)
• No “Proprietary Blends” (hidden dosages)
• Realistic, not exaggerated claims

Conclusion

The evidence-based supplement list for most people is short:

• Vitamin D (October-March at our latitudes)
• Protein powder (as needed to meet requirements)
• Creatine (for strength training)
• Omega-3 (with low fish consumption)

Everything else is situational or marketing. Invest first in high-quality food, good sleep, and a well-designed training programme.

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Sources:

• Kreider RB et al. (2017). International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation. Journal of the International Society of Sports Nutrition.
• Morton RW et al. (2018). A systematic review of protein supplementation on resistance training-induced gains. British Journal of Sports Medicine.
• Grgic J et al. (2020). Wake up and smell the coffee: caffeine supplementation and exercise performance. British Journal of Sports Medicine.
• Autier P et al. (2017). Vitamin D status and ill health: a systematic review. The Lancet Diabetes & Endocrinology.
• Sesso HD et al. (2012). Multivitamins in the prevention of cardiovascular disease in men. JAMA.