The other ingredients line is the one worth reading

Turn the bottle around. Under the Supplement Facts panel there's a short paragraph in smaller type, usually starting with the words "Other Ingredients." That paragraph is the whole bottle. Everything above it is marketing that had to be true. Everything in that line is what the manufacturer needed to physically get the powder into a shell and out of a machine at three thousand units an hour.

Most of it is harmless. Some of it is the reason your 1,000 mg capsule isn't a 1,000 mg capsule.

Capsules are small, and powder is bulky

A size 00 capsule, the common big one, holds somewhere around 700 to 1,000 mg of powder depending on how dense that powder is. Fluffy herb extract sits at the low end. Fine mineral salt sits at the high end. That's the physical ceiling, and no amount of label design gets around it.

So when the front of a bottle says 1,500 mg, look at the serving size. It's usually two capsules. Sometimes three. That's not dishonest, it's just arithmetic most people don't do in the aisle.

The second thing to check is the form. Magnesium oxide is about 60 per cent elemental magnesium by weight. Magnesium glycinate is closer to 14 per cent, because the glycine is most of the molecule. A 500 mg capsule of one and a 500 mg capsule of the other are not the same product, and the glycinate bottle will often print the compound weight in big type and the elemental weight in small type, if at all.

Check the second number.

What the fillers actually are

Microcrystalline cellulose. Purified wood or cotton pulp. It's a bulking agent. If you're taking 25 mcg of vitamin D, something has to occupy the other 99.99 per cent of the capsule or the powder rattles around and won't dose consistently. Cellulose is the usual something.

Rice flour, maltodextrin, dicalcium phosphate. Same job. Rice flour tends to show up in products sold as "clean label." Maltodextrin is a carbohydrate, which matters to roughly nobody at these quantities.

Magnesium stearate. A lubricant. It keeps powder from welding itself to the tooling. Typical inclusion is well under two per cent of the fill weight. The internet decided some years ago that it suppresses immune function, based on lab work done on isolated cells at concentrations you'd never get near by swallowing a capsule. If you want to avoid it anyway, buy powder in a tub. That's a real option and it's usually cheaper. But don't pay a premium for a "no magnesium stearate" claim as though you've dodged something.

Silicon dioxide. Anti-caking. Stops the powder clumping in humidity. It's sand, functionally.

Titanium dioxide. A whitener, mostly in the shell or a coating. The EU no longer permits it as a food additive. The US still does. If you'd rather not have it, it's easy to avoid, because plenty of manufacturers have already dropped it.

The shell itself. Gelatin is bovine or porcine. If that matters to you for religious reasons, the label will often say "gelatin" and nothing else, and you'll need to ask the company which animal. Vegetarian capsules are hypromellose, sometimes written as HPMC. Softgels are almost always gelatin.

Where the fillers stop being innocent

The problem isn't cellulose. It's when cellulose is most of what you're buying and the price is set as though it isn't.

Creatine monohydrate is the clearest example, because the effective daily amount is well established at about five grams. Five grams is roughly seven capsules at 750 mg of fill, assuming the fill is pure creatine, which it won't be. So a 120-capsule bottle is maybe two and a half weeks. A tub of the same powder is months of the same compound, and it's the same compound.

Do the sum before you buy: grams of active per day, divided into grams of active per container, and then price per gram. Not price per bottle. The bottle size is chosen to make that hard.

Where capsules genuinely win: anything you need a precise small dose of, anything that tastes foul, and anything you'll actually take. A tub of powder you have to scoop and stir at 6am, with a toddler hanging off one leg, is a tub you'll abandon by March. Convenience is a real variable. Just know what you're paying for it.

Proprietary blends

If the panel lists "Performance Matrix 750 mg" followed by eleven ingredients, you know the total and nothing else. Ingredients are listed by weight, descending. That means ingredient one could be 700 mg and ingredients two through eleven could be five milligrams each, present so they can be named on the front of the bottle.

This shows up most in pre-workouts, sleep formulas and anything with an "adaptogen" on the label. The tell is a long ingredient list against a small total blend weight.

My rule is simple. If I can't see the individual amounts, I assume the cheap ingredients are the big ones. That assumption is right often enough to be useful.

What third-party certification does and doesn't buy

NSF Certified for Sport, Informed Sport and USP Verified all mean an outside lab checked that what's on the label is in the bottle, and that a list of contaminants and banned substances isn't. That's meaningful. Supplements aren't approved before sale the way drugs are, and contamination in this category is a documented and recurring problem.

What certification does not tell you is whether the ingredient works. A certified bottle of something useless is a verified bottle of something useless.

It also costs more, and for a lot of people that's the wrong place to spend. If you're a serviceman, a tested athlete, or in any job with drug testing consequences, pay it without thinking. If you're a forty-year-old buying vitamin D, plain USP-grade from a large manufacturer with an actual address on the label is a reasonable place to land.

Ninety seconds in the aisle

• Serving size. Is it one capsule or three?
• Elemental weight versus compound weight for minerals.
• Any proprietary blend, and how many names are crammed into it.
• The Other Ingredients line, read to the end. Shellfish in glucosamine, soy lecithin in softgels, lactose in a few older formulations.
• Cost per gram of the thing you're actually after.

And this is general information, not advice for your situation. If you take prescription medication, ask the pharmacist before you add anything. They'll check interactions for free, in about two minutes, and they're better at it than the forum you were going to ask instead.

The part nobody prints on the bottle

Open your cabinet and count. Most people I know have seven or eight bottles and finish two. The rest get taken for eleven days in January and then sit there going stale while the family eats badly and sleeps six hours a night.

Three bottles you finish beat nine you don't. Pick the short list, buy the unglamorous version, and put it next to the kettle where you'll see it at half six tomorrow morning.