Best Selling Supplements on eBay in October 2026

Protein leads at 86.5% sell-through, 46,210 sales against 53,413 live listings, well clear of creatine at 55.7%. Those two are the only segments above the 54.8% the category manages. Omega follows at 49.9% and magnesium at 49.1%, then vitamins at 44.8% despite selling the most units. The slow end is collagen at 41.6%, probiotics at 41.1% and pre workout at 37.1%, the slowest and also the smallest segment on the page with 800 sales on 2,159 listings. Protein's lead owes something to how it is sold: a tub or bulk listing with multi quantity stock sells repeatedly while counting once as a listing, so read 86.5% as shelf turn rather than a clearance rate.

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 237,503 units by 433,581 listings observed in the same 30 days and gets 54.8%. One tub or bulk listing can sell repeatedly while counting once in the denominator. Protein shows the effect most clearly: 46,210 units against 53,413 listings, or 86.5%, far above the 37.1% to 55.7% the other seven segments run at. Use these numbers to rank segments against each other, not as the probability that any single listing sells. The comparison between segments is the useful part; the level itself is not a forecast for one listing.

It is the second largest segment on both units and money, and the fastest. Protein moved 46,210 units in the window and took $1,110,576, behind vitamins at 57,465 and $1,209,339, against 53,413 live listings at $24.03 a sale. That is 86.5% sell-through, the highest of the eight segments, on a High competition pool, and ZIK scores it Medium opportunity. Two cautions travel with it. The asking mean is $64.99, about 2.7 times what protein realises, so price against the sold column. And the segment is wider than powder: five of the ten highest volume listings sit under Protein, and they include protein bars at $4.43 and $5.90 and a collagen peptides multipack alongside whey powders at $14.91 and $47.69.

Magnesium and pre workout are the two segments ZIK scores Low competition, but only magnesium scores High opportunity alongside it; pre workout scores Medium and clears 37.1%, the slowest on the page. Magnesium clears 49.1% on 9,188 listings at $18.38 a sale. Omega and creatine are the other two High opportunity segments, both Medium competition: omega clears 49.9% on 22,013 listings and creatine 55.7% on 12,676. The catch is size. Those three segments are 22,569 units between them, under 14% of the 166,064 sales the eight segments account for. Against them, vitamins and collagen sit on 185,356 listings together and both score Low opportunity. The room and the volume are in different places.

The category averages $24.04 a sale. Segments barely separate: magnesium at $18.38 is the floor and collagen at $26.32 the ceiling, five cents above omega, 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 $47.58 a sale and collagen powder $30.92, against $18.19 for magnesium supplement and $18.90 for multivitamin, a range of about 2.6 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 $64.99 and realises $24.03, about 2.7 times. Omega asks $63.43 and realises $26.27. Collagen asks $51.43 against $26.32, vitamins $41.08 against $21.04, pre workout $46.08 against $25.90. The narrowest gap is magnesium, $29.99 against $18.38. 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 $558,669 of the category's $5,708,622, just under 10%, and 19,989 of its 237,503 units, from 0.6% of the live listings. That is a fragmented shelf, not a dominated one. Inside the ten, productivity varies enormously. esupplementsllc moved 5,926 units from 263 listings, the most units of the ten, while nutritionfirst moved 929 from 306. vitaminrush leads on revenue with $133,319 from 725 listings, the largest shelf of the ten. At the other extreme szsretail moved 921 units from 15 listings and buypl_24 moved 1,102 from 19, which is what a few deep multi quantity listings look like in this table.

Probiotics is the only term ZIK scores High demand, and it comes at Medium competition. Creatine is the other Medium competition term; the remaining eight come back Low. Whey protein, fish oil, multivitamin, collagen powder, magnesium supplement and vitamin d 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 $47.58 a sale and collagen powder $30.92, against $18.19 for magnesium supplement and $18.90 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 57,465 sales and still scores Low opportunity, while magnesium sells 4,511 and scores High: vitamins competes against 128,359 live listings, magnesium against 9,188. Omega and creatine score High by the same method, clearing 49.9% and 55.7% on Medium competition 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 166,064 of the category's 237,503 sales.