Vitamins and Supplements After Bariatric Surgery

Core Supplement Set

Multivitamin with iron and trace minerals (usually two daily)

Calcium citrate 1200–1500 mg/day split into doses

Vitamin D 3000 IU/day, adjusted by serum level

Vitamin B12 — oral, sublingual, or intramuscular per protocol

Iron — additional dosing for menstruating patients or after bypass

Why Bypass Needs More

Roux-en-Y and mini-gastric bypass bypass part of the duodenum and proximal jejunum, reducing absorption of iron, calcium, B12, and fat-soluble vitamins. Sleeve patients have lower but still real risk.

Laboratory Monitoring

Standard follow-up labs at 3, 6, 12 months and annually thereafter — including CBC, iron studies, B12, folate, 25-OH vitamin D, calcium, PTH, and selected trace elements.

When to Adjust

Symptoms such as fatigue, hair shedding, paresthesia, or bone pain warrant additional testing rather than self-adjustment of doses. Decisions about replacement should be guided by the bariatric team.

References

• ASMBS Integrated Health Nutritional Guidelines
• Mechanick JI et al., 2019 Perioperative Nutrition Update