About David Gans

My Weight-Loss Story

In January 2024 I walked into the operating room weighing over 400 pounds. I had gastric bypass surgery that morning, and it set off a transformation I'm still living every day. Over the months that followed, I lost 231 pounds. My mobility came back. My confidence came back. My life started over.

But the surgery was only the beginning. Afterward, I faced a question every bariatric patient eventually confronts: which vitamins do I actually need, and am I taking the right ones?

An honest note: I had bypass, not sleeve

I want to be upfront about this because it matters. I had gastric bypass in January 2024. I did not have a sleeve gastrectomy. So why run a site dedicated to sleeve vitamins?

Because the underlying nutrition science overlaps significantly. Calcium citrate targets, vitamin B12 dosing, vitamin D3 requirements, and daily protein goals are broadly similar across sleeve and bypass. The one key difference is iron: ASMBS recommends 18mg daily for sleeve patients versus 45mg or more for bypass patients, because the sleeve preserves duodenal absorption while bypass reroutes around it. That single distinction is well documented, and I treat it as the line in every recommendation on this site.

Being a bypass patient means I take these supplements every day, read every label, and understand the post-op reality from the patient side. Covering sleeve means doing that work twice: once from my own experience, and again from ASMBS guidelines and peer-reviewed literature specific to sleeve gastrectomy. I would rather tell you that directly than pretend otherwise.

Why I Built Sleeve Vitamins

As I dug into the research, I noticed something frustrating. Most vitamin comparison sites treat every bariatric procedure the same. They recommend the same high-iron formula to bypass patients and sleeve patients alike, even though the ASMBS publishes different guidelines for each surgery type.

Gastric sleeve patients keep their full intestinal tract, which means their absorption is less impaired than after bypass. They need 18mg of iron daily, not the 45mg or more that bypass patients require. Lumping the two groups together leads to sleeve patients either overpaying for nutrients they don't need or, worse, taking excessive iron that can cause GI side effects.

I created Sleeve Vitamins because sleeve patients deserve a dedicated resource that respects the 18mg iron line and the rest of the sleeve-specific ASMBS guidance. Every product on this site is evaluated against ASMBS sleeve gastrectomy guidelines. The comparison table defaults to an 18mg iron filter. The articles, the FAQ answers, and the recommendations all speak directly to sleeve nutrition, not a blended bariatric average.

What I Research and How

My methodology has three tiers, in this order. First, ASMBS Integrated Health Nutritional Guidelines: any recommendation has to line up with the 2016 and 2023 guideline documents for sleeve gastrectomy patients. Second, peer-reviewed clinical research: where the guidelines leave room for interpretation, I look at studies on post-sleeve nutrient status, absorption, and deficiency rates. Third, comparison to my own bypass nutrition, flagged clearly whenever I draw on it, because bypass and sleeve overlap heavily on calcium, B12, D3, and protein but diverge sharply on iron.

I spend my time reading clinical literature, comparing supplement labels, tracking prices, and talking to other bariatric patients. I've personally reviewed the formulas of every multivitamin listed on this site.

Sleeve Vitamins is reader-supported. When you purchase a product through an Amazon link on this site, I may earn a small affiliate commission at no cost to you. That support helps me keep the site running and the data up to date.

How I Review and Select Vitamins

Every vitamin that makes it onto this site goes through the same evaluation process. First, I check ASMBS compliance: the product must meet the 2016 ASMBS Integrated Health Nutritional Guidelines for sleeve gastrectomy patients, which means at least 18mg of elemental iron and 1,000mcg of vitamin B12 per daily serving. Products that miss either threshold are excluded, no exceptions.

From there I look at form factor. Chewables, capsules, and soft chews absorb differently after sleeve surgery, and some patients tolerate one format better than another. I note whether each product is practical for a post-op stomach. Gummies get a special flag because most are iron-free and don't qualify under sleeve guidelines.

Then I run the numbers on value per dose. I pull the lowest available price for a 90-day supply on Amazon and divide by 90 to get a daily cost. A vitamin is only worth recommending if it is also affordable over the long term, because sleeve patients take these supplements for life. Price alone never earns a product a top spot, but an identical formula at half the cost matters.

I review every listed product at least once per quarter. If a formula changes, a price shifts significantly, or new clinical literature updates the guidance, I revise the relevant pages. You'll find a “Updated [month] [year]” line at the top of every article so you always know how fresh the information is.

How we compare vitamins

Products are included only if they meet the ASMBS 2016 Integrated Health Nutritional Guidelines minimum for gastric sleeve patients: at least 18mg elemental iron and 1,000mcg vitamin B12 per daily serving. Products are ranked by price per day based on the cheapest available 90-day supply on Amazon. Nutrient values are taken directly from official supplement facts panels. The full nutrient comparison, including 21 micronutrients per serving, is available on the compare page. Prices are verified and updated weekly by David Gans.

Part of a three-site network

SleeveVitamins.com is part of an independent three-site comparison network:

• sleevevitamins.com: bariatric-labeled products, iron flagged against the 18mg ASMBS sleeve baseline, 15 products
• bypassvitamins.com: bariatric-labeled products, iron flagged against the 45mg ASMBS bypass baseline, 15 products
• bestbariatricmultivitamins.com: all surgery types combined, 15 products

All three sites are independently indexed by Google and cross-link to each other.

Affiliate transparency

This site participates in the Amazon Services LLC Associates Program. A small commission is earned when you purchase through our links, at no extra cost to you. This site may also partner directly with bariatric supplement brands. Affiliate relationships never determine which products are listed or how they rank. Every product earns its place by meeting ASMBS guidelines for sleeve patients.