Iron Bisglycinate: The Best-Tolerated Form for Restoring Your Iron Levels

Iron deficiency is the most common nutritional deficiency in the world, affecting around 25% of the world’s population according to the WHO. In France, it particularly affects women of childbearing age, endurance athletes, vegetarians and older people. But iron supplementation is often dreaded for its digestive side effects. Iron bisglycinate changes that. At Herba Barona, our specialist shop at 10 rue Théophile Roussel, Paris 12e, we explain why this form of iron has become the reference in 2026.

Understanding iron deficiency

Iron is an essential mineral involved in oxygen transport (haemoglobin), muscle oxygen storage (myoglobin), cellular energy production and numerous enzymatic reactions. An iron deficiency develops in three stages:

• Stage 1 — Depleted stores: ferritin drops (< 30 µg/L) but haemoglobin remains normal. Progressive fatigue, often blamed on stress.
• Stage 2 — Functional deficit: serum iron falls, binding capacity rises. Noticeable fatigue, breathlessness on exertion, paleness.
• Stage 3 — Iron-deficiency anaemia: haemoglobin drops (< 12 g/dL in women, < 13 g/dL in men). Intense fatigue, dizziness, rapid heartbeat, hair loss.

Serum ferritin is the earliest and most sensitive marker of iron deficiency. It’s advisable to aim for ferritin above 50 µg/L for an optimal status, not merely above the lab’s low threshold (often set at 15 µg/L).

Why is iron bisglycinate superior?

The problem with classic forms of iron

Ferrous sulfate, the form most commonly prescribed in medicine, is certainly effective but frequently causes digestive side effects: nausea, constipation, black stools, abdominal cramps. These unpleasant effects lead many people to give up their supplementation before restoring their iron stores. Ferrous fumarate and gluconate cause the same issues, though to a lesser degree.

The bisglycinate solution

Iron bisglycinate is a chelated form in which the iron atom is bound to two glycine molecules. This chelation provides several decisive advantages:

• Superior absorption: iron bisglycinate is absorbed via the amino acid pathway (peptide transporters), in addition to the classic iron pathway (DMT1). This dual absorption route significantly increases the amount of iron that reaches the bloodstream.
• Excellent digestive tolerance: the iron stays chelated throughout its transit through the stomach and small intestine. It doesn’t come into direct contact with the digestive lining, which practically eliminates gastrointestinal side effects.
• No interaction with food: unlike ferrous sulfate, bisglycinate isn’t blocked by phytates (cereals, legumes), tannins (tea, coffee), calcium or fibre. It can therefore be taken with meals.
• No black stools: chelated iron doesn’t colour the stools, a welcome practical benefit.

Form of iron	Bioavailability	Digestive tolerance	Food interaction	Black stools
Iron bisglycinate	Excellent	Excellent	No	No
Ferrous sulfate	Good	Poor	Yes (phytates, tannins, calcium)	Yes
Ferrous fumarate	Good	Moderate	Yes	Yes
Ferrous gluconate	Moderate	Moderate	Yes	Yes
Carbonyl iron	Good	Fair	Partial	Yes

Our selection of iron in Paris

• Iron bisglycinate Dynveo 60 capsules: 14 mg of elemental iron per capsule, true chelation, DRcaps vegetable capsules. The reference for quality.
• Fer3 Dynveo — Iron and Vitamin C Complex 60 capsules: a synergistic formula combining iron bisglycinate with natural vitamin C (acerola) to optimise absorption. Ideal for pronounced deficiencies.
• Iron bisglycinate Novoma 90 capsules: excellent value for money for a longer course, dosed at 14 mg of elemental iron.
• VEGIFER Flamant Vert tablets: a natural alternative based on spirulina, rich in iron and phycocyanin, for those who prefer a food-based source.

Find our full range in the Iron category.

Iron and vitamin C: an essential synergy

Vitamin C (ascorbic acid) improves the absorption of non-haem iron by reducing it from its ferric form (Fe3+) to its ferrous form (Fe2+), which is more easily absorbed. Taking 50 to 100 mg of vitamin C alongside iron can double or even triple absorption. With iron bisglycinate, this synergy is less critical (since absorption is already optimal), but it remains beneficial. Dynveo’s Fer3 formula builds this synergy directly into the product.

Populations at risk of iron deficiency

• Women of childbearing age: menstruation causes a loss of 15 to 30 mg of iron per cycle. Needs are 16 mg/day, compared with 11 mg/day for men.
• Pregnant women: needs triple during pregnancy (30 mg/day) due to increased blood volume and foetal development.
• Endurance athletes: running causes mechanical haemolysis (destruction of red blood cells in the foot capillaries), increasing iron losses.
• Vegetarians and vegans: non-haem iron from plants is absorbed 2 to 3 times less efficiently than the haem iron found in meat.
• Older people: intestinal iron absorption declines with age, and diets are often less varied.

How to optimise your iron supplementation

• Blood test first: get your ferritin tested before starting supplementation. Iron excess is just as problematic as deficiency (oxidative stress).
• Regular intake: consistency matters more than dosage. One capsule a day for 3 months is more effective than 3 capsules a day for 1 month.
• Avoid tea and coffee: tannins reduce iron absorption. Wait 1 to 2 hours after taking it (less important with bisglycinate).
• Re-test at 3 months: get another ferritin test after 3 months of supplementation to assess effectiveness and adjust if needed.

Frequently asked questions about iron bisglycinate

Can iron bisglycinate cause constipation?

No, that’s actually one of its major advantages. Thanks to its chelation, iron bisglycinate causes neither constipation nor nausea, unlike classic ferrous sulfate. It’s the best-tolerated form of iron for the digestive system.

Can you take iron alongside zinc?

Iron and zinc compete for the same intestinal transporters. It’s best to take them at different times of day (for example, iron in the morning and zinc in the evening). With the bisglycinate forms of both minerals, this interaction is reduced but can still occur at high doses.

Where to find quality iron bisglycinate in Paris?

At Herba Barona, 10 rue Théophile Roussel, Paris 12e (metro Ledru-Rollin), we stock Dynveo and Novoma iron bisglycinate, the two leading references on the French market. Our team is here to advise you Tuesday to Saturday, 9:30am–6:30pm.