Supplements on Ozempic: Essential Nutrients for GLP-1 Users
When you're eating 1000–1500 calories daily on GLP-1, you miss critical micronutrients. This guide explains which supplements matter, why, and what to take.
The Core Problem
Rapid, severe caloric restriction + small meal portions = micronutrient deficiency risk. Add to that GLP-1's effects on nutrient absorption (particularly B12), and supplementation isn't optional—it's essential.
Tier 1: Non-Negotiable Supplements
Vitamin B12 (Critical)
Why:
- GLP-1 slows stomach emptying, reducing intrinsic factor production (needed for B12 absorption)
- Rapid weight loss depletes B12 stores
- Deficiency causes: fatigue, brain fog, neuropathy, hair loss, depression
- B12 is found primarily in animal products; eating less means less intake
Who's at risk:
- Everyone on GLP-1
- Especially: vegetarians, older adults, history of pernicious anemia
Dosing:
- Oral supplementation: 1000–2000 mcg daily or 2000 mcg weekly
- Injectable (if deficiency detected): 1000 mcg monthly (more reliable absorption, but prescription)
- Cost: £5–15 per month (oral)
Timing:
- Sublingual (under tongue) is better than swallowed tablets (bypasses stomach acid issues)
- Take on empty stomach for best absorption
Brands to try:
- Vitabiotics B12 (UK-made, reliable)
- Nature's Way B12
- Solgar B12 (sublingual)
Shop B12 supplements on Amazon UK
When to check bloodwork:
- Get B12 level checked before starting GLP-1 (baseline)
- Recheck at 6 months
- If <400 pg/mL, ask prescriber about injectable B12
Magnesium Glycinate (Critical for Most)
Why:
- GLP-1 causes constipation (magnesium helps)
- Small calorie intake = less magnesium from food
- Magnesium deficiency worsens: constipation, muscle cramps, anxiety, sleep problems, fatigue
Dosing:
- 300–400 mg daily (glycinate form is best; gentlest on stomach)
- Take in divided doses if over 400 mg (e.g., 200 mg morning, 200 mg evening)
- Take with food to minimize digestive upset
Why glycinate specifically:
- Most absorbable form
- Won't cause diarrhoea (unlike magnesium citrate)
- Gentle on GLP-1 stomach
- Glycine itself has calming effects
Shop magnesium glycinate on Amazon UK
When to skip:
- If you develop diarrhoea (magnesium can worsen it)
- If kidney function is compromised
High-Quality Multivitamin (Insurance Policy)
Why:
- Fills nutritional gaps from low-calorie eating
- Covers bases if you're missing certain food groups
What to look for:
- Contains: B vitamins, Vitamin D, Vitamin A, minerals (Zn, Cu, Mn, Se)
- Avoids: Excessive iron (only supplement if deficient) or excess calcium (interferes with absorption)
- Form: Whole-food based (e.g., Naturelo, Pure Synergy) absorb better than synthetic
Brands worth trying:
- Naturelo One Daily Multivitamin (whole-food based, good value)
- Tru Niagen One (includes NAD+ precursor; emerging longevity support)
- Pure Synergy Multi (premium, excellent ingredients)
Dosing:
- Daily with food
Tier 2: Highly Recommended
Vitamin D3 + K2
Why:
- ~80% of UK population is deficient in Vitamin D
- Low calorie eating = less vitamin D from food
- Vitamin D deficiency worsens: mood, bone health, immune function, fat loss
- K2 improves D3 absorption and calcium metabolism
Dosing:
- D3: 1000–4000 IU daily (more in winter, less in summer if sun exposure good)
- K2: 100–200 mcg daily (ensure MK-7 form, not MK-4)
Timing:
- Take with fat-containing meal (D3 is fat-soluble)
When to check bloodwork:
- Vitamin D levels (<30 ng/mL is deficient, 30–49 is insufficient, 50+ is optimal)
Shop Vitamin D3+K2 on Amazon UK
Zinc (Especially Important for Hair Health)
Why:
- GLP-1 users risk hair loss (telogen effluvium); zinc deficiency exacerbates it
- Low calorie eating reduces zinc intake
- Zinc supports: immune function, skin health, wound healing
Dosing:
- 15–30 mg daily (bisglycinate form is best)
- Don't exceed 40 mg daily without medical supervision (excess zinc interferes with copper absorption)
Timing:
- Take with food to minimize nausea
- Not with calcium, iron, or copper (competes for absorption)
Shop zinc bisglycinate on Amazon UK
Omega-3 (Fish Oil)
Why:
- Anti-inflammatory (supports metabolic health, weight loss)
- Supports brain health (omega-3 deficiency linked to depression, cognitive decline)
- May support skin health during rapid weight loss
- Most UK people don't eat enough oily fish
Dosing:
- 2–3 grams EPA+DHA combined daily
- Check label for actual EPA+DHA content (not total fish oil)
Form:
- Fish oil (most researched)
- Algae oil (vegan option, though less studied)
Timing:
- Take with food (fat-soluble; improves absorption and reduces fish burps)
Tier 3: Consider If Specific Risk
Iron
Important caveat: Only supplement if bloodwork shows deficiency.
Why relevant to GLP-1:
- Hair loss on GLP-1 is partly driven by low iron (ferritin <30 ng/mL)
- Low calorie eating reduces iron intake
- Women especially at risk (menstruation)
Dosing (if deficient):
- 15–25 mg elemental iron daily
- Iron glycinate is gentler than iron sulfate
Timing:
- Take on empty stomach for best absorption (but may cause nausea; take with food if needed)
- Don't take with coffee, tea, calcium, or magnesium (interferes)
When to check:
- Ask for ferritin + serum iron before starting GLP-1
- Recheck at 3 months if deficient
- Supplement only if <30 ng/mL
Biotin (For Hair Loss)
Evidence: Mixed and modest; some benefit, not proven miracle.
Dosing:
- 2.5–5 mg daily (biotin is measured in micrograms, so this is very high dose)
When to consider:
- Hair loss is significant or you're very concerned about it
- Protein + zinc + iron already addressed
Brands:
- Vitabiotics Biotin
- Solgar Biotin
Calcium (Only if Avoiding Dairy)
Important: Most people get enough calcium from food (even reduced portions). Only supplement if you're avoiding dairy entirely.
Dosing:
- 1000–1200 mg daily (if deficient from low intake)
- Split into 500 mg doses (better absorption)
- Take separately from magnesium, iron, zinc (interferes)
Why avoid excess: Too much calcium impairs iron and zinc absorption (especially problematic on GLP-1).
Tier 4: Probably Skip (or Justify Carefully)
Collagen (for Skin & Hair)
Evidence: Modest for skin elasticity; less clear for hair.
Reality: You're getting collagen precursors (amino acids) from adequate protein. Standalone collagen supplementation is expensive for uncertain benefit.
Verdict: Skip if protein intake is good; consider if you're genuinely concerned about skin elasticity.
Biotin Injections
Hype vs. reality: Injected biotin marketed for hair loss. Little evidence supports it beyond placebo.
Verdict: Skip. Focus on protein, iron, zinc instead.
Appetite Suppressants (e.g., Garcinia, Glucomannan)
Verdict: Unnecessary and potentially dangerous on GLP-1 (appetite already suppressed). Don't add extra appetite suppression.
Supplement Schedule: Simple Approach
Morning (with breakfast):
- Multivitamin
- Vitamin D3+K2
- Omega-3
- Zinc
Evening (with dinner):
- Magnesium glycinate
- B12 (if taking daily) or standalone
Alternate days if preferred:
- B12 twice weekly instead of daily (still effective)
- Omega-3 every other day (not as good, but acceptable)
Cost-Effective Supplement Stack
All recommended, minimal cost (~£30–50/month):
- Standard multivitamin: £6–10/month
- B12 (sublingual): £5–8/month
- Magnesium glycinate: £5–8/month
- Vitamin D3+K2: £5–8/month
- Zinc bisglycinate: £3–5/month
- Omega-3 (bulk): £8–12/month
Total: ~£32–51/month
Budget-conscious? Prioritize: Multivitamin + B12 + Magnesium. These three cover most gaps.
When to Get Bloodwork
Before starting GLP-1:
- Vitamin B12, ferritin, iron, Vitamin D, magnesium (serum), zinc
After 3 months:
- B12, ferritin, Vitamin D (if supplementing)
After 6–12 months:
- Full micronutrient panel (especially B12, ferritin, Vitamin D)
Private option: Medichecks.com offers affordable bloodwork in UK (£40–150 per panel).
Red Flags: When to Seek Help
Contact your doctor if:
- B12 < 300 pg/mL (consider injectable instead of oral)
- Ferritin < 20 ng/mL (significant deficiency; may need IV iron)
- Vitamin D < 20 ng/mL (severe deficiency; consider prescription strength)
- Signs of zinc toxicity (nausea, headaches, copper deficiency symptoms)
Key Takeaway
Minimum supplement stack on GLP-1: Multivitamin + B12 + Magnesium
Ideal stack: Add Vitamin D3+K2 + Zinc + Omega-3
Avoid: Appetite suppressants, unnecessary "anti-aging" pills, anything unproven
Next Steps
- Full nutrition guide for GLP-1
- Protein on GLP-1
- Hair loss prevention (zinc, iron, protein)
- Managing constipation (magnesium)
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Disclaimer: This is educational information. Consult your prescriber or a registered dietician before starting any supplements, especially if you take medications.