What Is Iron Glycinate? A guide to iron for women's health

Learn what iron glycinate is, how it compares to ferrous sulphate, and why iron matters for Aussie women's health, from diet to supplementation. 

Iron is one of the most researched minerals in women's health. As interest in iron supplements has grown, so has the range of formulations available, each with its own characteristics. Iron glycinate is one form that comes up often in consumer research, alongside terms like iron bisglycinate and ferrous sulphate. 

This article looks at what iron glycinate is, how it compares with other iron formulations, why iron matters across a woman's life stages, and what to consider when it comes to iron intake and testing. 

What is iron glycinate?

Iron glycinate is a form of iron that has been paired with glycine, an amino acid the body already uses. This pairing changes how the iron behaves as it moves through the digestive system and is one of the reasons iron glycinate is often described as a gentle form of iron. 

Different iron supplements use different forms of iron. Some are harsher on the stomach than others, and some are absorbed more easily than others. Iron glycinate sits at the gentler, better-absorbed end of that range. 

Iron itself is an essential mineral, which means the body can't make it on its own. Iron has to come from food, and in some cases, from a supplement when dietary intake is inadequate. 

Iron glycinate and iron bisglycinate: are they the same?

In most cases, yes. Iron glycinate and iron bisglycinate refer to the same ingredient. "Bisglycinate" is the more scientific name, while "iron glycinate" is the shorter version often used on supplement labels and in articles. 

When comparing iron supplements, the number that matters most is the elemental iron content, sometimes shown on labels as "equivalent iron." This is the amount of iron your body can actually use, not the total weight of the ingredient. For example, an 87.7 mg tablet of iron (II) glycinate delivers about 24 mg of elemental iron. 

How iron glycinate differs from ferrous sulphate

Ferrous sulphate is the most widely used form of iron in supplements. It's inexpensive, contains a high dose of iron per tablet, and has been used for decades. It's also the form most often linked to side effects like nausea, constipation and stomach discomfort, which can make it difficult to keep taking. 

A systematic review and meta-analysis published in PLOS ONE reviewed 43 randomised controlled trials involving 6,831 adults. Across the 20 trials that compared ferrous sulphate with placebo, ferrous sulphate was associated with a higher likelihood of gastrointestinal side effects. A separate subgroup analysis of pregnant women found the same pattern of increased gastrointestinal side effects. 

Iron glycinate is a gentler option. Because the iron is paired with an amino acid, less unabsorbed iron is left in the digestive tract, which is what tends to cause the discomfort. Iron glycinate is also generally absorbed more easily by the body, which means smaller doses can still support healthy iron levels when dietary intake is inadequate. 

A systematic review and meta-analysis published in Nutrition Reviews examined the effects of ferrous bisglycinate compared with other oral iron supplements in adults and children. The review reported that in pregnant women, ferrous bisglycinate was better tolerated in the gut, with comparable or greater effects on haemoglobin at lower elemental iron doses than the comparator iron formulations. 

For anyone who has struggled with iron supplements in the past, or who simply prefers a lower-nausea, one-a-day option, the difference in formulation is worth raising with a pharmacist or healthcare professional. 

Why stomach comfort matters in iron supplementation

Iron supplements are among the most commonly discontinued nutritional supplements, largely because of digestive side effects. When people stop taking a supplement before it has time to be useful, the benefit of taking it is lost. 

Gentler iron forms aim to address this by binding iron in a way that reduces the amount of free iron interacting with the stomach lining. This is one reason why formulations like iron glycinate are often positioned as an option for people who haven't tolerated other iron supplements well, or who prefer a low nausea approach from the outset. 

Tolerability is not just about comfort. It also supports consistency, which matters for any nutrient that works gradually. 

The role of iron in the body

Iron plays several fundamental roles. It's a key component of haemoglobin, the protein in red blood cells that carries oxygen from the lungs to tissues throughout the body. It's also part of myoglobin, which stores oxygen in muscle tissue, and contributes to a range of enzymes involved in energy production. 

According to Healthdirect, iron is needed to produce red blood cells to support immune function, mental function, and energy. When iron intake is inadequate over time, the body draws down on its stored iron reserves, which can eventually affect these processes. 

Because the body doesn't produce iron, meeting daily requirements through diet, and where needed through supplementation, matters throughout life. 

Why women may need more iron across different life stages

Iron requirements vary by age, sex and life stage. According to the Nutrient Reference Values published by NHMRC, the Recommended Dietary Intake (RDI) for iron in Australia is: 

• Women aged 19 to 50 years: 18 mg per day
• Women aged 51 years and over: 8 mg per day
• Pregnant women: 27 mg per day
• Breastfeeding women: 9 to 10 mg per day

The higher requirement in women of reproductive age reflects the iron lost through menstruation, while the increase during pregnancy accounts for the greater blood volume, the growth of the developing baby, and the placenta. 

Analysis from the Australian Bureau of Statistics National Nutrition and Physical Activity Survey, released in March 2026, found that females were more than three times as likely as males to have an inadequate iron intake (26.8% compared with 8.2%). Among women of reproductive age specifically, inadequacy rates were substantially higher: nearly half (47.7%) of women aged 18 to 29 and around four in ten (42.2%) of women aged 30 to 49 had an inadequate iron intake from food and beverages in 2023. Rates dropped sharply after menopause (around one in ten among women aged 50 and over), tracking the reduction in iron requirements once menstrual iron losses cease. 

Certain groups may find it harder to meet their iron needs through diet alone, including those following vegetarian or vegan diets, those with heavier menstrual bleeding, and those going through pregnancy or breastfeeding. A conversation with a healthcare professional is the appropriate starting point for anyone thinking about supplementation. 

Signs of low iron women may notice

Iron plays such a broad role in the body that when intake is consistently low, the effects can be non specific and easy to attribute to other causes. According to Healthdirect, signs that may be associated with low iron include feeling tired or weak, shortness of breath, dizziness or light-headedness, trouble concentrating and remembering things, and pale skin. 

These signs are non specific, meaning many other factors can produce similar experiences. This is why self-diagnosis is not recommended. A GP can order blood tests to see whether iron intake or absorption is the underlying factor. 

Persistent tiredness, unusually heavy periods, or ongoing digestive concerns are all reasons to see a healthcare professional rather than reaching for a supplement first. Testing gives you and your GP a clear picture and helps determine what, if anything, is needed. 

Understanding ferritin and iron testing

Ferritin is the protein your body uses to store iron. A small amount of ferritin also circulates in the blood, and this level reflects the size of your iron reserves. As Healthdirect explains, a ferritin blood test measures the amount of stored iron in the body and is one of several tests included in an iron studies panel. 

An iron studies test typically measures: 

• Serum iron: the amount of iron circulating in the blood
• Ferritin: stored iron
• Transferrin: a protein that carries iron in the blood
• Transferrin saturation: how much of the transferrin is bound to iron

An iron studies test needs to be requested by a GP or another healthcare provider. Results are interpreted alongside a full blood count and in the context of your individual history. Values that appear within the reference range may still warrant follow up if symptoms or other factors suggest reduced iron stores. 

Women in higher risk groups, such as those with heavy periods, plant-based eaters, blood donors, and those planning pregnancy or already pregnant, may benefit from a discussion with their GP about whether iron studies are appropriate.

Iron-rich foods and dietary considerations

Meeting iron needs through food is the foundation of adequate iron intake. Dietary iron comes in two forms: haem iron, found in animal sources and more readily absorbed, and non-haem iron, found in plant sources. 

Good dietary sources of iron include: 

• Lean red meat, poultry and fish (haem iron)
• Eggs
• Legumes such as lentils, chickpeas and beans
• Tofu and tempeh
• Wholegrain and iron-fortified cereals
• Nuts and seeds
• Dark green leafy vegetables such as spinach and silverbeet

The NHMRC Nutrient Reference Values note that iron absorption is approximately 18% from a mixed western diet including animal foods and about 10% from a vegetarian diet, meaning vegetarians typically need higher total iron intakes. This is one reason why vegetarian and vegan eaters may need to be more attentive to their iron intake. 

Absorption of non-haem iron can be supported by pairing plant-based iron sources with foods rich in vitamin C, such as citrus fruits, capsicum, tomatoes and berries. Tea, coffee, calcium-rich foods and some medications can reduce iron absorption when consumed at the same meal. 

How to take iron supplements for better tolerability

If iron supplementation is being considered, timing and technique influence how well it is tolerated.  

General guidance for most oral iron formulations includes: 

• Taking iron with a meal that contains vitamin C to support absorption
• Spacing iron away from tea, coffee, calcium-rich foods, and calcium supplements by at least two hours
• Starting with the recommended dose on the label rather than higher doses, unless a healthcare professional has advised otherwise
• Taking iron consistently, since iron stores rebuild gradually
• Continuing to talk to a GP if side effects such as constipation or nausea remain a barrier

Some iron formulations, including iron glycinate, are designed to be taken with food, which can further support tolerability. Following the label instructions and, where relevant, healthcare professional guidance is always the best starting point. 

Where iron glycinate supplementation may fit

For women whose dietary iron intake is inadequate, and who are looking for a gentle, one-a-day option, iron glycinate is one formulation to consider alongside food-first strategies. 

Blackmores Iron Glycinate is formulated with iron (II) glycinate 87.7 mg (equivalent to 24 mg of elemental iron) per tablet. It is designed to maintain iron levels in the body when dietary intake is inadequate, to assist healthy red blood cell production and helps oxygen transport to body tissues when dietary intake is inadequate, and to support energy production and help relieve tiredness, fatigue and feelings of weakness when dietary intake is inadequate. It is also indicated to help support a healthy pregnancy and maternal health when dietary intake is inadequate. 

The formulation is a one-a-day tablet, taken with food. It is not for the treatment of iron deficiency conditions. Vitamins and minerals can only be of assistance if dietary intake is inadequate. Supplements should not replace a balanced diet. 

If you are pregnant or planning pregnancy, advise your doctor of any medicine you take, particularly in your first trimester. Always talk to your healthcare professional before combining multiple products for pregnancy.

When to speak to a healthcare professional

There are several situations where seeing a healthcare professional is the right first step, rather than starting a supplement: 

• Persistent tiredness that hasn't responded to changes in sleep, stress, or diet
• Consistently heavy or prolonged menstrual periods
• Digestive symptoms that could affect nutrient absorption
• Planning a pregnancy, currently pregnant, or breastfeeding
• Following a vegetarian or vegan diet and wanting a check on iron status
• Being a regular blood donor

• Managing an existing health condition or taking medications regularly

A GP can arrange the appropriate blood tests and based on the results, provide personalised guidance about diet, testing frequency, or supplementation.

Frequently asked questions

What is iron glycinate? 

Iron glycinate is a form of iron in which iron is bound to the amino acid glycine. This chelated form is generally associated with lower rates of gastrointestinal side effects compared with some other iron formulations. 

Is iron glycinate the same as iron bisglycinate? 

In most consumer supplement contexts, yes. The term iron bisglycinate refers to the chemical structure in which each iron ion is bound to two glycine molecules, and iron glycinate is often used as a shorter version of the same name. 

How is iron glycinate different from ferrous sulphate? 

Ferrous sulphate has long been the standard oral iron form and delivers a high dose of elemental iron per tablet. It has been associated with a higher rate of gastrointestinal side effects than some other iron forms, including nausea, constipation and stomach discomfort. Ferrous bisglycinate (iron glycinate) is generally better tolerated in the digestive tract and, because of its higher bioavailability, is often used at lower elemental iron doses while still contributing to iron intake when dietary intake is inadequate. 

When should women see their HCP to see if getting their iron levels checked is needed? 

Women who experience persistent tiredness, heavy menstrual bleeding, are pregnant or planning pregnancy, follow vegetarian or vegan diets, or donate blood regularly may benefit from a conversation with their GP about iron studies. The GP will order the appropriate blood tests and interpret the results in context. 

Should iron supplements be taken with food? 

Following the label instructions is the best guide. Iron glycinate formulations are generally taken with food. Some other iron forms may be recommended on an empty stomach. Taking iron with a source of vitamin C can support absorption of non-haem iron. 

How long do iron supplements take to work? 

Iron works gradually, and iron stores rebuild over weeks to months. Because ferritin responds slowly, changes are usually monitored over several months rather than days or weeks. A healthcare professional can guide the appropriate timeframe for follow-up testing. 

Key takeaways

Iron glycinate is a chelated form of iron generally associated with lower rates of gastrointestinal side effects than some other oral iron formulations. It is often referred to interchangeably with iron bisglycinate in consumer contexts. Ferrous sulphate remains a widely used iron form, though it has been associated with a higher rate of gastrointestinal side effects in research. 

Australian data from the ABS suggests around one in four women have an inadequate iron intake, with rates approaching one in two among women aged 18 to 29. Iron needs vary considerably across life stages, with pregnancy carrying the highest requirement. Meeting iron needs through food is the foundation, with dietary patterns and life stage influencing how easily this is achieved. 

Because low iron shares symptoms with many other factors, and because iron is best assessed through blood testing rather than self-diagnosis, anyone concerned about their iron levels should speak with a GP before starting a supplement. Where iron supplementation is appropriate and dietary intake is inadequate, iron glycinate is one option to discuss.

Always read the label and follow the directions for use.

Disclaimer: This article provides general information only and is not intended to diagnose, treat, cure, or prevent any disease. The information presented is not a substitute for professional medical advice. If you have concerns about your health, please consult your GP or healthcare provider for a personalised assessment and recommendations. Supplements should not replace a balanced diet.