Thorne Iron Supplement Review
Iron deficiency affects nearly one in three adults, yet many iron supplements cause uncomfortable side effects like constipation, nausea, and stomach upset. Thorne Research has addressed this problem with their Iron Bisglycinate supplement, which promises enhanced absorption without the typical gastrointestinal issues. But does this premium iron supplement justify its higher price? We’ve tested Thorne’s iron products and compared them to other leading brands to help you determine if they’re the right choice for your iron supplementation needs.
Our Top Picks at a Glance
Best Overall: Thorne Iron Bisglycinate 25mg – Gentle, well-absorbed iron with minimal side effects
Best for Severe Deficiency: Thorne Advanced Iron Complex (Ferrasorb) – 36mg iron with vitamin C and B vitamins for enhanced absorption
Best Budget Option: Iron Supplement for Women – Chelate iron bisglycinate with vitamin C and B12
Best for Women: Pink Stork Total Women’s Multivitamin – Comprehensive formula with iron, B vitamins, and biotin
Best Gentle Formula: Iron Supplement Liquid Drops – Fast-absorbing iron with MCT oil for minimal GI distress
Best for Kids: Iron Bisglycinate Gummies – Chelated iron in kid-friendly gummy format with vitamin C
Detailed Product Comparisons
| Product | Iron Amount | Form | Additional Nutrients | Price Range |
|---|---|---|---|---|
| Thorne Iron Bisglycinate | 25mg | Capsule | None (pure iron) | $$$ |
| Thorne Advanced Iron | 36mg | Capsule | C, B6, B12, folate | $$$ |
| Iron + Vitamins for Women | 25mg | Capsule | C, B6, B12, folic acid | $$ |
| Pink Stork Women’s Multi | 18mg | Capsule | 19 vitamins/minerals | $$ |
| Iron Liquid Drops | 15mg per serving | Liquid | MCT oil, grape flavor | $$ |
| Iron Gummies for Kids | 25mg | Gummy | Liposomal vitamin C | $$ |
| Gentle Iron for Pregnancy | 18mg | Tablet | C, B12, B6, folic acid | $$ |
In-Depth Product Reviews
1. Thorne Iron Bisglycinate – 25mg
Thorne’s flagship iron supplement uses iron bisglycinate chelate, a form that’s significantly more absorbable and gentler on the stomach than conventional iron supplements. Each capsule provides 25mg of elemental iron, which is ideal for addressing mild to moderate iron deficiency without overwhelming your system.
What We Like:
- Bisglycinate chelate form dramatically reduces constipation and nausea compared to ferrous sulfate
- NSF Certified for Sport ensures it’s tested for banned substances, important for athletes
- Higher absorption rate means you get more usable iron with less gastrointestinal distress
- Trusted by over 100 professional sports teams and recommended by healthcare practitioners
- Gluten-free and free from unnecessary additives or fillers
- 60 capsules provide a two-month supply at the standard one-per-day dosage
What Could Be Better:
- Premium pricing makes it more expensive than conventional iron supplements
- 25mg dose may be insufficient for severe iron deficiency (though higher doses can be taken with doctor guidance)
- No additional nutrients like vitamin C to enhance absorption further
Bottom Line: Thorne Iron Bisglycinate excels as a gentle, highly absorbable iron supplement that minimizes the side effects that make many people quit taking iron. While more expensive than drugstore options, the superior tolerability and absorption make it worthwhile for those who struggle with conventional iron supplements. This is particularly valuable for athletes, menstruating women, or anyone who has experienced GI issues with other iron products.
2. Thorne Advanced Iron Complex (Formerly Ferrasorb)
For those needing more aggressive iron supplementation, Thorne’s Advanced Iron Complex provides 36mg of iron bisglycinate along with vitamins C, B6, B12, and folate. This comprehensive formula enhances iron absorption while supporting red blood cell production through multiple pathways.
What We Like:
- Higher 36mg iron dose suitable for moderate to severe deficiency
- Vitamin C (15mg) enhances iron absorption significantly
- B vitamins (B6, B12, folate) support healthy red blood cell formation and prevent related deficiencies
- Methylcobalamin form of B12 and 5-MTHF form of folate are more bioavailable
- Non-constipating bisglycinate form makes higher doses tolerable
- Addresses multiple aspects of blood health in one supplement
What Could Be Better:
- More expensive than basic iron supplements due to additional nutrients
- Higher dose may cause mild side effects in iron-sensitive individuals
- Not necessary if you only need pure iron supplementation
Bottom Line: The Advanced Iron Complex is ideal for addressing diagnosed iron deficiency anemia or for those at high risk. The combination of iron with supporting nutrients creates a more comprehensive blood-building formula. While the premium price and higher dose aren’t necessary for everyone, those with confirmed deficiency will appreciate the thoughtful formulation that addresses red blood cell production from multiple angles.
3. Iron Supplement for Women with Chelate Iron Bisglycinate
This budget-friendly option provides the same chelated iron bisglycinate form as Thorne but at a more accessible price point. With 25mg of gentle iron plus vitamins C, B6, B12, and folic acid, it offers comprehensive support for women’s iron needs.
What We Like:
- Chelated iron bisglycinate provides gentle absorption like premium brands
- Includes vitamin C to enhance iron absorption by converting it to a more absorbable form
- B vitamins support energy production and combat fatigue beyond just iron’s effects
- Folic acid supports healthy menstrual function and overall blood health
- 120-count bottle provides excellent value for a four-month supply
- Specifically formulated for women’s menstrual health and iron requirements
What Could Be Better:
- Uses folic acid rather than methylfolate, which may be less bioavailable for some people
- Not as extensively tested or backed by research as premium brands like Thorne
- May contain more fillers and additives compared to cleaner formulations
Bottom Line: This offers excellent value for women needing gentle iron supplementation without premium pricing. The chelated form and vitamin combination make it comparable to more expensive options in terms of tolerability and absorption. While it may not have Thorne’s reputation or testing standards, it’s a solid mid-range choice that delivers results for most women at a reasonable cost.
4. Pink Stork Total Women’s Multivitamin
Rather than standalone iron, this comprehensive women’s multivitamin includes 18mg of iron along with 18 other essential vitamins and minerals. It’s designed to support energy, metabolism, hormone balance, immune function, and mood – all areas affected by iron status and overall nutrition.
What We Like:
- Provides daily iron needs within a complete multivitamin, simplifying supplementation
- B6, B12, and biotin support energy production and combat the fatigue associated with low iron
- Zinc and vitamin C support immune function while also enhancing iron absorption
- Addresses hormone balance and metabolism, important for menstruating women
- One-capsule daily dose makes it convenient and easy to remember
- Third-party tested and doctor-formulated specifically for women
What Could Be Better:
- 18mg iron content may be insufficient for those with diagnosed iron deficiency
- Can’t adjust iron dose independently from other nutrients
- Monthly supply (30 capsules) requires more frequent reordering
Bottom Line: This multivitamin works well for women wanting to maintain healthy iron levels preventively rather than treat deficiency. The comprehensive nutrient profile addresses multiple aspects of women’s health beyond just iron. While not suitable for severe deficiency treatment, it’s an excellent all-in-one option for general wellness and preventing deficiency before it starts.
5. Iron Supplement Liquid Drops for Women and Men
For those who struggle with swallowing pills or have severe GI sensitivity, this liquid iron supplement offers an alternative delivery method. With MCT oil for enhanced absorption and natural grape flavor to mask the metallic taste, it provides 15mg of iron per serving in a fast-absorbing format.
What We Like:
- Liquid format absorbs faster than capsules or tablets
- MCT oil base enhances absorption and reduces gastrointestinal distress
- Natural grape flavor makes it more palatable than typical liquid iron
- Can be easily mixed into juice or smoothies for those sensitive to taste
- Dosage can be adjusted more precisely than with fixed-dose pills
- Blood builder formula supports overall hematological health
What Could Be Better:
- Lower 15mg dose per serving may require taking more for adequate supplementation
- Some users still detect metallic taste despite grape flavoring
- Liquid format requires refrigeration after opening and has shorter shelf life
- Can stain teeth if not taken properly (use a straw or rinse mouth afterward)
Bottom Line: Liquid iron fills an important niche for people who can’t tolerate pills or need faster absorption. The MCT oil base and natural flavoring make it more pleasant than traditional liquid iron supplements. While the lower dose and liquid format may not suit everyone, it’s an excellent option for children, elderly adults, or anyone with swallowing difficulties or extreme GI sensitivity.
6. Iron Bisglycinate Gummies 25mg for Kids and Adults
These iron gummies make supplementation more palatable for children and adults who dislike swallowing pills. With 25mg of chelated iron and liposomal vitamin C, they provide effective iron supplementation in a kid-friendly format without compromising on quality or absorption.
What We Like:
- Gummy format makes iron supplementation accessible for children and pill-averse adults
- Chelated iron bisglycinate is gentle even in gummy form
- Liposomal vitamin C enhances iron absorption significantly
- Pleasant taste encourages consistent daily use
- One-month supply in convenient gummy format
- Suitable for both children and adults with appropriate dosing
What Could Be Better:
- Contains added sugars and natural flavors to make them palatable
- More expensive per dose than traditional iron capsules
- Must be kept away from children to prevent accidental overdose (they taste like candy)
- Some adults prefer capsules for serious supplementation
Bottom Line: These gummies successfully solve the challenge of getting children and pill-averse adults to take iron consistently. The combination of gentle chelated iron and absorption-enhancing vitamin C makes them effective despite the gummy format. While they cost more and contain added sugars, the compliance benefit often outweighs these drawbacks, especially for children who need iron supplementation.
7. Gentle Iron Supplement for Pregnant Women
Designed specifically for pregnancy and anemia support, this gentle iron supplement uses slow-release SunActive technology to minimize stomach upset. With 18mg of iron plus folic acid, B12, vitamin C, and B6, it addresses the increased iron needs during pregnancy without the typical prenatal vitamin side effects.
What We Like:
- Patented SunActive technology provides slow-release iron for minimal GI distress
- 18mg dose meets pregnancy iron requirements for most women
- Folic acid supports healthy fetal neural tube development
- Vitamin C and B6 enhance iron absorption and reduce pregnancy-related nausea
- Clinically shown to support iron levels in pregnant women with anemia
- Smaller tablet size easier to swallow during pregnancy
What Could Be Better:
- Lower 18mg dose may be insufficient for women with severe iron deficiency
- Smaller 20-tablet package means more frequent reordering
- Not a complete prenatal vitamin, so additional supplementation needed
Bottom Line: This iron supplement specifically addresses pregnant women’s needs with gentle, effective supplementation. The slow-release technology makes it tolerable even during the first trimester when nausea is common. While not a complete prenatal solution, it provides excellent targeted support for women who need additional iron beyond what’s in their prenatal vitamin or who can’t tolerate the iron in their prenatal.
Understanding Thorne’s Iron Bisglycinate Advantage
Thorne uses iron bisglycinate chelate, which represents a significant advancement over conventional iron supplements. In this form, iron is bound to two glycine molecules, creating a stable chelate that protects the iron as it passes through your digestive system. This chelation process prevents the iron from interacting with other food components that could inhibit absorption while also reducing the oxidative stress that causes typical iron supplement side effects.
The result is an iron supplement that’s absorbed up to four times more efficiently than ferrous sulfate, the most common iron form in drugstore supplements. Because your body absorbs more of the iron from each dose, you can take less iron to achieve the same blood-building effects, which further reduces side effects.
Thorne’s commitment to quality extends beyond just ingredient selection. Their iron supplements undergo four rounds of testing, from raw material analysis to finished product verification, ensuring consistent potency and purity. NSF certification for their sports products provides additional assurance that they’re free from banned substances and contaminants.
Benefits of Thorne Iron Supplements
Dramatically Reduced Side Effects: The bisglycinate form causes significantly less constipation, nausea, and stomach upset compared to ferrous sulfate or ferrous gluconate. This improved tolerability means you’re more likely to take it consistently, which is essential for correcting deficiency.
Superior Absorption: Chelated iron bisglycinate is absorbed through different pathways than non-chelated iron, bypassing some of the factors that typically inhibit iron absorption. You can even take it with coffee or tea without significantly reducing absorption, unlike conventional iron supplements.
Suitable for Sensitive Individuals: People with inflammatory bowel disease, gastritis, or other digestive conditions often can’t tolerate standard iron supplements. The gentle nature of bisglycinate makes it accessible to those who have failed with other iron products.
Professional-Grade Quality: Thorne’s reputation among healthcare practitioners and professional athletes stems from their rigorous testing protocols and consistent quality. When you need reliable results, professional-grade supplements provide peace of mind.
Flexible Dosing: Unlike slow-release iron that must be taken on a specific schedule, Thorne’s bisglycinate can be taken with or without food at any time of day. This flexibility improves compliance and allows you to find the timing that works best for your digestion.
Buying Guide: Choosing the Right Iron Supplement
Get Tested Before Supplementing: Never start iron supplementation without first confirming deficiency through blood testing. Too much iron can be harmful, and symptoms of iron deficiency overlap with many other conditions. Ask your doctor for a complete iron panel including ferritin, not just hemoglobin.
Understand Your Iron Form: Ferrous bisglycinate (chelated) is the gentlest and most absorbable form. Ferrous sulfate is cheap but causes the most side effects. Ferrous gluconate and ferrous fumarate fall somewhere in between. Carbonyl iron is an alternative for those who can’t tolerate any organic iron form.
Calculate Your Actual Iron Needs: Iron supplements list elemental iron content, which is what your body actually uses. A 325mg ferrous sulfate tablet contains only 65mg elemental iron. Compare products based on elemental iron content, not total compound weight.
Consider Additional Nutrients: Vitamin C significantly enhances iron absorption – look for supplements that include it or take vitamin C separately. B vitamins, particularly B12 and folate, support red blood cell production and can be beneficial if your deficiency is severe.
Evaluate Your Tolerance: If you’ve struggled with iron supplements before, start with chelated bisglycinate forms like Thorne’s. If even these cause issues, try liquid iron, slow-release formulations, or discuss IV iron with your doctor for severe deficiency.
Check for Interactions: Iron can interfere with thyroid medication, certain antibiotics, and other supplements like calcium and zinc. Take iron at least 2-4 hours apart from these medications and supplements for optimal absorption of both.
Plan for Long-Term Use: Correcting iron deficiency takes time – typically 2-3 months to restore hemoglobin and 6 months or longer to rebuild iron stores. Choose a supplement you can tolerate for extended periods and plan for regular blood tests to monitor progress.
Frequently Asked Questions
How quickly will I see results from iron supplementation?
Most people begin feeling more energetic within 2-4 weeks as their hemoglobin levels start to rise, but complete restoration of iron stores takes much longer. You’ll need to continue supplementation for at least 3-6 months even after symptoms improve to fully replenish your body’s iron reserves. Your doctor should retest your iron levels after 2-3 months to assess progress and adjust dosage if needed.
Why is Thorne iron so much more expensive than drugstore iron?
Thorne uses premium iron bisglycinate chelate, which costs significantly more to manufacture than the ferrous sulfate used in cheap supplements. Additionally, Thorne’s rigorous testing protocols, NSF certification, and quality control measures add to production costs. However, the superior absorption means you need less iron to achieve results, and the dramatically reduced side effects mean you’re more likely to take it consistently. For many people, the premium is worthwhile.
Can I take iron with my morning coffee?
While conventional wisdom says to avoid taking iron with coffee due to absorption interference, chelated iron bisglycinate is less affected by tannins in coffee and tea. That said, you’ll still absorb slightly more if you take it separately. For maximum absorption, take iron with vitamin C and away from coffee, calcium, antacids, and high-fiber foods. If timing is difficult, taking chelated iron with coffee is better than not taking it at all.
What’s the difference between iron bisglycinate and ferrous bisglycinate?
These terms are often used interchangeably. “Ferrous” indicates the iron is in the Fe2+ oxidation state, which is the form your body absorbs. “Bisglycinate” means it’s chelated with two glycine molecules. So “ferrous bisglycinate” and “iron bisglycinate” refer to the same thing – chelated iron in its absorbable form. Some products may also call it “ferrochel” which is a branded form of ferrous bisglycinate chelate.
Can iron supplements cause dark stools?
Yes, dark or black stools are a normal and expected side effect of iron supplementation. Your body doesn’t absorb 100% of supplemental iron, and the unabsorbed iron darkens your stool as it passes through your digestive system. This is harmless and actually indicates that you’re taking iron. However, if you experience black tarry stools with a different consistency or blood in your stool, contact your doctor as this could indicate a different problem.
Do I need to take iron if I eat red meat?
Not necessarily. Dietary iron from red meat (heme iron) is well absorbed, and many people maintain healthy iron levels through diet alone. However, menstruating women, pregnant women, vegetarians, vegans, and people with certain medical conditions may need supplementation even with good dietary iron intake. Blood testing is the only way to know if you need supplementation – don’t assume based on diet alone.
Can I take too much iron?
Yes, iron overload is dangerous and can damage your organs, particularly your liver and heart. This is why you should never supplement iron without confirming deficiency through testing. Accidental iron overdose is also a leading cause of poisoning deaths in children under six, so always keep iron supplements securely stored away from children. If you or a child accidentally takes too much iron, call poison control immediately.
Why am I still tired even though I’m taking iron?
Several possibilities exist: Your iron levels may not have risen enough yet (allow 2-4 weeks minimum), you may have absorption issues preventing the iron from working, your fatigue may be caused by something other than iron deficiency, or you may have additional deficiencies like vitamin B12 or vitamin D. Continue taking your iron supplement as directed and follow up with your doctor if fatigue persists after 4-6 weeks. They may need to adjust your dose or investigate other causes.
