Supplements I recommend,ranked by evidence.

Creatine monohydrate. One of the most studied supplements in sports nutrition. With strength training, it supports gains in strength and lean mass. The International Society of Sports Nutrition found long-term use safe in healthy adults. Most people take 3 to 5 grams a day, every day, at any time.

Protein powder. Food first, but a shake makes your daily target easy to hit. A 2018 meta-analysis of 49 trials with 1,863 people found that during strength training, extra protein stopped adding lean mass at about 1.6 grams per kilogram of body weight per day. For a 200 pound person, that's about 145 grams a day.

Vitamin D. Low levels are common in people who work indoors. Test first, then supplement to your number with your doctor's input.

Omega-3s. Worth considering if you rarely eat fatty fish. Pick a brand with third-party testing.

Caffeine. A proven training aid. The ISSN position stand found 3 to 6 milligrams per kilogram of body weight improves performance, most often taken about an hour before training. The minimum effective dose may be as low as 2 milligrams per kilogram. Start low, and cut it off early enough to protect your sleep.

Electrolytes. Useful if you sweat heavily or train in the heat.

Magnesium. Almost half of US adults get less magnesium from food than they need. If your diet is light on greens, beans, nuts, and whole grains, this is an easy gap to close.

Daily nutrient pack. For busy weeks when meals get skipped. In national survey data, adults who took a multivitamin most days had far fewer nutrient gaps, though calcium, magnesium, and vitamin D often stayed short.

These have good early research behind them, but smaller studies. I use them, and I'll tell you exactly how strong the evidence is.

Collagen. Collagen isn't a complete protein, so it doesn't replace your shake. In a 12 week trial of 53 older men lifting three times a week, 15 grams of collagen peptides a day led to more lean mass, more strength, and more fat loss than a placebo.

Colostrum. The first milk a cow produces, rich in immune proteins. A 2016 review of five small trials in people who train regularly found about 44 percent fewer days with upper respiratory symptoms. The trials were small, so I call this promising, not proven.

Joint support. In a small 8 week pilot study, trained men with joint pain from training took Cissus quadrangularis, and their joint pain scores fell about 31 percent. There was no placebo group, so treat it as early evidence.

Talk to your doctor before starting any supplement, especially if you take medication, are pregnant, or have a medical condition. These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.

Checked against PubMed.

• Kreider RB, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. J Int Soc Sports Nutr. 2017;14:18. DOI
• Morton RW, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376-384. DOI
• Guest NS, et al. International Society of Sports Nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr. 2021;18(1):1. DOI
• Rosanoff A, Weaver CM, Rude RK. Suboptimal magnesium status in the United States: are the health consequences underestimated? Nutr Rev. 2012;70(3):153-164. DOI
• Blumberg JB, et al. Impact of frequency of multi-vitamin/multi-mineral supplement intake on nutritional adequacy and nutrient deficiencies in U.S. adults. Nutrients. 2017;9(8):849. DOI
• Zdzieblik D, et al. Collagen peptide supplementation in combination with resistance training improves body composition and increases muscle strength in elderly sarcopenic men: a randomised controlled trial. Br J Nutr. 2015;114(8):1237-1245. DOI
• Jones AW, et al. Bovine colostrum supplementation and upper respiratory symptoms during exercise training: a systematic review and meta-analysis of randomised controlled trials. BMC Sports Sci Med Rehabil. 2016;8:21. DOI
• Bloomer RJ, et al. Cissus quadrangularis reduces joint pain in exercise-trained men: a pilot study. Phys Sportsmed. 2013;41(3):29-35. DOI