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Bypass VitaminsThe independent comparison

Gastric Bypass Vitamin Guides

Research-backed articles for bypass patients. Iron, B12, calcium, vitamin D, thiamine, zinc, protein, and more. Written by David Gans, updated weekly.

Product Comparison8 min read

Best Multivitamin After Gastric Bypass Surgery (2026)

My top 3 editorial picks ranked by price per day, iron content, and patient reviews. Updated April 2026.

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Nutrition Guide12 min read

What Vitamins Do You Need After Gastric Bypass Surgery?

A complete guide to iron, B12, calcium, and vitamin D after Roux-en-Y. ASMBS daily targets and why regular vitamins fall short.

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Iron Guide10 min read

How Much Iron Do You Need After Gastric Bypass?

Bypass patients need 45-60mg of elemental iron daily per ASMBS. Why elemental iron is counted, ferritin targets, and lab schedule.

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B12 Guide9 min read

How Much B12 Do You Need After Gastric Bypass?

1,000mcg daily in sublingual or liquid form. Why normal B12 absorption fails after Roux-en-Y and how to prevent nerve damage.

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Vitamin D Guide8 min read

Vitamin D After Gastric Bypass: What You Need to Know

ASMBS recommends 3,000 IU of D3 daily. Why D3 outperforms D2 and why low vitamin D silently damages your bones.

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Calcium Guide10 min read

Best Calcium Citrate Supplement After Gastric Bypass (2026)

5 calcium citrate products ranked by price per day, dosing guidance, and why citrate beats carbonate after bypass.

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Thiamine Guide9 min read

Thiamine After Gastric Bypass: Why B1 Matters

Thiamine deficiency can develop within weeks after bypass. ASMBS targets, warning symptoms, and why programs exceed the 12mg minimum.

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Zinc Guide10 min read

Zinc Deficiency After Gastric Bypass: Symptoms and Solutions

Zinc deficiency affects up to 40% of bypass patients. Symptoms, 8-22mg target, best forms, and why copper balance matters.

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Troubleshooting8 min read

Do Bariatric Vitamins Cause Nausea? What Bypass Patients Need to Know

Nausea from bariatric vitamins is common and almost always fixable. Iron form, timing, and which multivitamins are gentlest.

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Supplement Guide7 min read

Gummy Vitamins After Gastric Bypass: Why They Fall Short

Why gummy vitamins are not recommended after gastric bypass, and what a complete bariatric formula should actually contain.

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Protein Guide8 min read

Best Protein Powder After Gastric Bypass: Label Math That Works

60-100g protein daily after surgery. How to choose a powder using bariatric goals: 20-30g per serving, under 5g sugar, 100-200 calories.

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Recovery Guide10 min read

Hair Loss After Gastric Bypass: Causes and What Helps

Hair loss after bypass is common and often temporary. Which deficiencies play a role, protein targets, and when to ask for labs.

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Product Comparison5 min read

Compare Calcium Citrate Products

Interactive calcium citrate comparison for bypass patients. Filter by form, brand, rating, or price per day.

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