Every common supplement sorted into three piles: worth it for most people, depends on your situation, and mostly hype. With what the evidence says and where to check it yourself.
Creatine tops off the quick-energy system your muscles run on during the first few seconds of hard effort, which buys you an extra rep or two, and those reps add up over months. It's the most-studied supplement there is: strength, lean mass, and some evidence for thinking clearly on short sleep. Vegetarians and older adults start lowest and tend to notice most. Skip the loading phase. The kidney scare is a myth in healthy people.
Treat it as convenient food, not magic. What counts is your total for the day, and powder is just the cheapest, fastest way to close the gap when you're 30 grams short at nine at night. Spread it across meals instead of loading one giant shake. One catch: collagen powder doesn't count toward the target.
Fills the gap when oily fish isn't a regular part of the diet. EPA and DHA are the two fats your body can barely make on its own, and they're the reason salmon and sardines get all the credit. Freshness matters more than the exact dose here. Rancid fish oil is common, so break a capsule open and smell it, and if it reeks, toss the bottle.
Plenty of people run a little low, mostly because leafy greens, beans, and nuts don't show up often enough. Most people take it for sleep or for muscle cramps, and the evidence there is decent without being dramatic. The form genuinely matters: glycinate and citrate absorb well, and oxide mostly just gives you loose stools.
One of the few performance aids that reliably works. It blunts how hard the effort feels, so you push a little longer before you quit. The catch is timing. Caffeine hangs around for five or six hours, so a 3 p.m. coffee is still working at bedtime, and sleep is when training actually turns into muscle.
Fixing a real shortage is worth doing, and the usual suspects are people who work indoors all day, live somewhere with long grey winters, or have darker skin. Topping up when you're already in range isn't. The large trials handed D to people who weren't short and saw no drop in fractures, cancer, or heart disease. Test first, then treat the number.
B12 shows up almost exclusively in animal foods, so a plant-based diet is a real gap and not a theoretical one. Absorption also drops with age, which catches people who eat plenty of meat and assume they're covered. A shortage builds quietly over years and can damage nerves before you feel much, so don't wait for symptoms to act.
Not what the jar implies. Swallowing collagen doesn't deliver collagen to your skin. Your gut breaks it into fragments first, and those fragments seem to signal your own cells to build more of their own. Expect modest gains in skin hydration and elasticity, and less for joints. It won't reverse arthritis or grow hair, and it isn't muscle protein, so don't count it toward your daily target.
Menstruating women, endurance athletes, blood donors, and vegetarians are the usual low groups, and the flat, worn-out feeling it causes gets blamed on everything else first. But this is the real test-don't-guess nutrient. Your body has no way to dump what it doesn't need, so extra iron builds up and does damage. Confirm low ferritin before you touch it.
Real uses exist, but they're narrow. The best evidence is for heading off the diarrhea antibiotics cause and for easing some IBS symptoms. Benefits belong to specific strains studied for specific problems, not to the category, so the strain printed on the label is the whole product. The broad "gut health and immunity" marketing is mostly hype.
A cheap safety net for the days your diet slips, and that's the whole pitch. Large trials keep looking for a drop in heart disease, cancer, or early death from taking one and keep coming up empty. If you already eat a decent variety of food, it mostly buys you expensive urine. Harmless, occasionally useful, never the thing that moves the needle.
Worth it when you're actually losing salt: long sweaty sessions, hot weather, or a low-carb diet, which flushes sodium out fast. That's when water alone leaves you crampy and foggy. Everyone else gets plenty from food already. Ignore the brands pushing you to megadose sodium, because you're not running an ultramarathon through Death Valley.
Ordinary salt is all sodium. These blends swap a quarter to half of it for potassium chloride, and both halves of that trade push blood pressure down. In a five-year trial of 21,000 older adults in rural China, most with high blood pressure or a past stroke, the swap cut strokes by 14 percent and deaths by 12 percent. Almost nothing else on this page has outcome numbers that good. But if you have kidney disease or take an ACE inhibitor, an ARB, or spironolactone, you can't clear the extra potassium and it builds to a dangerous level. Ask your doctor before you switch.
Three of the 20 amino acids, sold at a premium. Whey is already full of them, and so are chicken, eggs, and milk. Building muscle takes the complete set, so supplying three of them is like dropping off three studs and calling it a wall. Hit your protein target and these are redundant.
Mostly maltodextrin, which is a dressed-up word for sugar. A 1,200-calorie scoop costs more than the food it replaces and leaves you too bloated to eat dinner. Whole milk, peanut butter, oats, and a banana in a blender hits the same number for a couple of dollars and actually keeps you full.
Test boosters lean on ingredients like tribulus and D-aspartic acid that don't budge testosterone in healthy men. Fat burners are mostly caffeine with a markup, plus stimulants that raise your heart rate more than they move the scale. Anything that truly changed either number that much would be a prescription, not a tub on a shelf.
Your body makes plenty of it on its own, and protein-rich food covers the rest. Glutamine earned its reputation in hospitals, where burn and trauma patients genuinely run short. That doesn't carry over to a healthy person lifting three times a week. Studies on muscle, recovery, and immunity in that group keep coming back flat.
Not harmful, just oversold. A scoop holds a gram or two of dried vegetable, nowhere near the fiber, water, and sheer volume of an actual plate of broccoli, and the "proprietary blend" hides how little of each ingredient made it in. If feeling covered means you eat fewer real vegetables, it's a net loss.
They fill gaps in an already-decent diet.
The FDA does not approve supplements before they're sold.
Bloodwork (vitamin D, B12, ferritin, omega-3 index) beats blanket dosing.
Fat-soluble vitamins (A, D, E, K) and minerals can build up and become toxic in excess.
Age, vegan or vegetarian diets, pregnancy, and existing medications all change the math.
Sources · NIH Office of Dietary Supplements · Examine.com · ISSN Position Stands · Cochrane Reviews · Mayo Clinic / Cleveland Clinic · ConsumerLab / Labdoor
This is a personal takeaway for general education, not medical advice. Reflects the consensus as of early 2026 — individualize with a doctor or registered dietitian.