Best Selling Supplements on eBay in September 2026

Pre workout leads at 87.9% sell-through, then creatine at 74.5%, magnesium at 63.6% and omega at 61.6%. The slow end is collagen at 52.8% and probiotics at 55.5%, with vitamins at 57.1% despite selling the most units. Protein derives to 112.6%, which is above what the ratio can honestly mean, so it is explained below rather than ranked. Setting protein aside, the eight segments run from 52.8% to 87.9%, a spread of under two to one, so speed separates them far less sharply than listing counts do. The fast end is also the thin end: pre workout's 87.9% comes from 1,664 sales on 1,893 listings, the smallest segment on this page.

Because the ratio measures shelf turn, not the odds a listing sells, and a supplement is a repurchased consumable often sold from multi quantity stock. The category divides 265,759 units by 381,857 listings observed in the same 30 days and gets 69.6%. One tub or bulk listing can sell repeatedly while counting once in the denominator. Protein makes the limit visible: 52,655 units against 46,747 listings, or 112.6%, which cannot be a clearance rate. ZIK publishes that figure with its explanation rather than capping it, because capping it would hide the mechanism. Use these numbers to rank segments against each other, not as the probability that any single listing sells.

It is the second largest segment on units and the largest on money. Protein moved 52,655 units in the window and took $1,424,118, narrowly ahead of vitamins at $1,415,727, against 46,747 live listings at $27.05 a sale. Two cautions travel with it. The segment derives to 112.6% sell-through for the multi quantity reason above, so it is not a clearance rate. And one row in that table, a 12 count box of protein bars at $200 a unit, carries $100,400 of that revenue while the three protein listings above it average $17. Strip that row and vitamins leads revenue by about $92,000. The revenue crown is inside the margin of error.

Magnesium and pre workout are the two segments ZIK scores Low competition, and both score High opportunity alongside it. Magnesium clears 63.6% on 8,036 listings at $19.44 a sale; pre workout clears 87.9% on 1,893 listings at $23.85. Creatine is the third High opportunity segment and the only one of the three at real scale, clearing 74.5% on 10,735 listings for 7,998 sales. The catch is size. Those three segments are 14,776 units between them, under 8% of the 189,699 sales the eight segments account for. Against them, vitamins and collagen sit on 164,851 listings together and both score Low opportunity. The room and the volume are in different places.

The category averages $25.65 a sale. Segments barely separate: magnesium at $19.44 is the floor and collagen at $28.04 the ceiling, a spread of under one and a half times. This is a low ticket, high frequency category, and choosing a different segment will not change much about what you take per sale. Buyer search terms spread wider. Whey protein averages $42.74 a sale and pre workout $32.16, against $18.29 for magnesium supplement and $19.54 for multivitamin, a range of about two and a third times. So the difference is made inside a segment, by format and pack size, rather than between segments. Volume and sourcing cost decide the outcome here.

Because a listing is an offer and only the realised column describes money that changed hands. Every segment on this page asks more than it gets. Protein is listed at an average of $67.50 and realises $27.05, two and a half times. Omega asks $66.02 and realises $27.45. Collagen asks $53.08 against $28.04, vitamins $41.95 against $21.60, pre workout $46.23 against $23.85. The narrowest gap is creatine, $39.02 against $26.59. The usual cause is multi packs and bulk lots sitting unsold at high sticker prices while single tubs do the selling, which pulls the mean of what is listed above the mean of what sold. Price against the realised column.

Nobody here is big. The top ten sellers take $689,064 of the category's $6,816,104, close to 10%, and 23,008 of its 265,759 units, from 1.2% of the live listings. That is a fragmented shelf, not a dominated one. Inside the ten, productivity varies enormously. esupplementsllc moved 6,797 units from 264 listings, while nutritionfirst moved 864 from 2,491, roughly ten times the shelf for an eighth of the sales. vitaminrush leads on revenue with $156,180 from 779 listings. quick_basket_deals shows $104,121 and 703 units from 5 listings, about $148 each, which sits on the same $200 protein bar pricing as the product table and should not be read as a normal result.

Probiotics is the only term ZIK scores High demand, and the only one at Medium competition; the other nine come back Low competition. Whey protein, creatine, collagen powder, fish oil, multivitamin, vitamin d and magnesium supplement all read Medium demand against Low competition, which is the pairing worth listing into. Price separates the terms more than demand does: whey protein averages $42.74 a sale and pre workout $32.16, against $18.29 for magnesium supplement and $19.54 for multivitamin. One caution. All ten terms come back Rising, which is what this short window signal does when velocity runs hot across a whole category, so treat it as directional and lean on demand, price and competition.

ZIK weighs units sold, sell-through and competition together rather than ranking on volume alone. That is why vitamins leads on units with 65,539 sales and still scores Low opportunity, while pre workout sells 1,664 and scores High: vitamins competes against 114,724 live listings, pre workout against 1,893. Creatine and magnesium score High by the same method, clearing 74.5% and 63.6% on light shelves. Every figure comes from ZIK's own marketplace data for the trailing 30 days. Two limits are stated on the page rather than smoothed away: sell-through here is shelf turn on a repurchased consumable and not per listing odds, and the eight segments cover 189,699 of the category's 265,759 sales.