GLP-1 and Vitamin Deficiencies: Which Nutrients Ozempic Depletes and How to Replace Them

GLP-1 and Vitamin Deficiencies: Which Nutrients Ozempic Depletes and How to Replace Them

By Dr. Onikepe Adegbola, MD PhD — Johns Hopkins-trained physician-scientist and founder of Casa de Sante

Nutrient-by-Nutrient Guide

Protein

• Risk level: HIGH
• Why: Protein-rich foods (meat, eggs, dairy) are often the first foods patients reduce or avoid due to nausea and early satiety. Protein requires more digestive effort than carbs.
• Consequence: Muscle loss, hair loss, weakened immunity, poor wound healing
• Target: 1.0-1.6g/kg/day. Most GLP-1 patients get less than 0.8g/kg without conscious effort.
• Solution: Protein shakes, protein-first eating (eat protein before carbs at every meal), easily tolerable protein sources (Greek yogurt, eggs, protein smoothies).

Vitamin B12

• Risk level: MODERATE-HIGH
• Why: B12 absorption requires adequate stomach acid and intrinsic factor. GLP-1 may alter gastric pH. Reduced meat intake (the primary dietary B12 source) compounds the risk.
• Consequence: Fatigue, brain fog, peripheral neuropathy (tingling in hands/feet), anemia, depression
• Test: Serum B12 (goal >400 pg/mL) and methylmalonic acid (MMA — more sensitive)
• Solution: Supplement 1,000-2,000 mcg methylcobalamin daily, or sublingual B12 (bypasses GI absorption).

Iron

• Risk level: MODERATE-HIGH (especially in menstruating women)
• Why: Iron absorption requires stomach acid. Reduced red meat intake is the primary dietary factor. Nausea discourages iron-rich foods.
• Consequence: Fatigue, pallor, hair loss, brain fog, exercise intolerance, restless legs
• Test: Ferritin (goal >30 ng/mL, ideally >50 ng/mL for optimal energy). CBC for anemia.
• Solution: Iron bisglycinate (better absorbed, less GI side effects than ferrous sulfate). Take with vitamin C. Take on an empty stomach or 2 hours after eating. Do NOT take with calcium.

Vitamin D

• Risk level: HIGH (often pre-existing deficiency worsened by GLP-1)
• Why: Vitamin D is fat-soluble — absorbed with dietary fat. Reduced fat intake on GLP-1 impairs absorption. Many patients are already deficient before starting the medication.
• Consequence: Bone loss, depression, immune dysfunction, muscle weakness, increased fall risk
• Test: 25-OH vitamin D (goal 40-60 ng/mL)
• Solution: Vitamin D3 2,000-5,000 IU daily (adjust based on blood levels). Take with a fat-containing meal for absorption.

Calcium

• Risk level: MODERATE
• Why: Dairy avoidance (nausea trigger), reduced overall food intake, and vitamin D deficiency (which impairs calcium absorption) all contribute.
• Consequence: Bone loss (especially concerning during rapid weight loss, which already reduces bone density)
• Solution: 1,000-1,200mg daily from food + supplement. Calcium citrate is preferred (does not require stomach acid for absorption).

Zinc

• Risk level: MODERATE
• Why: Zinc is primarily found in meat and shellfish. Reduced intake + potential malabsorption.
• Consequence: Impaired taste (which further reduces appetite — vicious cycle), hair loss, poor wound healing, immune dysfunction
• Solution: 15-30mg zinc daily. Zinc picolinate or zinc bisglycinate for best absorption.

Magnesium

• Risk level: MODERATE
• Why: Reduced food intake + GI side effects (diarrhea) deplete magnesium.
• Consequence: Muscle cramps, insomnia, anxiety, constipation, heart palpitations
• Solution: Magnesium glycinate 200-400mg at bedtime (supports both magnesium levels and sleep).

Testing Schedule

Every GLP-1 patient should have baseline and periodic (every 6 months) labs:

• CBC (anemia screen)
• Ferritin (iron stores)
• Vitamin B12 and folate
• 25-OH vitamin D
• Comprehensive metabolic panel (includes calcium)
• Magnesium
• Zinc (if symptomatic)