Best Iron UK 2026 — Expert Picks
Iron deficiency is the most common nutritional deficiency worldwide, and it hits UK women particularly hard. But not all iron supplements are equal — some wreck your stomach while others absorb beautifully. Here is what we recommend.
Gentle Iron 25mg (Iron Bisglycinate)
Solgar — Non-constipating chelated iron
Pros
- Bisglycinate form is very gentle
- Highly bioavailable
- No stomach upset or constipation
Cons
- Pricier than basic iron tablets
- Lower dose may need doubling for severe deficiency
Spatone Liquid Iron Sachets
Spatone — Natural spring water iron source
Pros
- Naturally sourced from Welsh spring
- Very gentle on stomach
- Can mix with orange juice for absorption
Cons
- Lower iron per sachet (5mg)
- Expensive for the iron content
Iron + Vitamin C Complex
Nutravita — Iron paired with vitamin C for enhanced absorption
Pros
- Added vitamin C boosts absorption by up to 67%
- 28mg iron per tablet
- One year supply
Cons
- Ferrous form may cause dark stools
- Not as gentle as bisglycinate
Ferrous Fumarate 210mg
GP Prescribed — Standard NHS-prescribed iron
Pros
- High elemental iron content (68mg)
- Very cheap
- Proven to correct deficiency
Cons
- Commonly causes constipation and stomach pain
- Harsh on digestive system
Active Iron
Solvotrin Therapeutics — Clinically proven 2x absorption
Pros
- Targets the natural absorption site
- Clinically shown to cause fewer side effects
- Non-constipating for most
Cons
- Premium pricing
- Only 14mg iron per capsule
Buying Guide: What to Look For
Iron bisglycinate is the gentlest form with excellent absorption. Always take iron with vitamin C (orange juice works) and avoid taking with tea, coffee, or calcium which block absorption. Only supplement if you have confirmed deficiency via blood test. Ferritin below 30 typically indicates the need to supplement.
Frequently Asked Questions
How do I know if I need iron supplements?
Get a blood test checking serum ferritin (not just haemoglobin). Symptoms include fatigue, breathlessness, pale skin, dizziness, and brittle nails. Women with heavy periods and vegans are at higher risk.
Why does iron cause constipation?
Ferrous forms (sulphate, fumarate) are poorly absorbed, and unabsorbed iron irritates the gut lining. Chelated forms like bisglycinate absorb much better and rarely cause constipation.
Can I take iron and other vitamins together?
Avoid taking iron with calcium, zinc, or magnesium as they compete for absorption. Take iron with vitamin C. Space iron 2 hours from tea, coffee, and dairy.
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