Nature Made Iron 65 mg (325 mg Ferrous Sulfate) Review
Product Focus: Adrenal SupportAlso covers:Hormones
Tier ⓘ
Tier 4 · Rank 7
Tier 4 · Emerging. A promising mechanism or animal data, with thin human evidence so far. Rank 7 within Tier 4 for Adrenal Support; 20 of 22 overall. Tiers run from 1, the strongest evidence, to 5. How we grade →
Evidence ⓘ
15 /100
How strongly the evidence says this product works: human studies count most, then real reviews, then our biohacker panel.
Biohacker Mentions
0 of 10
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Study, Trial or Testing Result Summary
Members Only12 human studies · 7 improved
5 of these 12 human studies gave iron by drip, not by mouth.
12 human studies7 improved4 no effect3,071 people studied
This product gives 65 milligrams of iron a day, close to the 80 milligrams used in the one study that looked directly at the stress hormone cortisol. That study was small: in 18 elite male cyclists during a three week stage race, iron taken for 4 weeks lowered cortisol by 13.5 percent, while cortisol rose 24.7 percent without iron [1]. Larger pregnancy trials found that iron given alone did not change cortisol in mothers or their children [2][3][4]. Several trials in people low in iron found that iron eased tiredness, though most used intravenous iron rather than tablets like this one. These include women with severe fatigue after childbirth [5], people with anemia over 12 weeks [6], and runners given iron injections. In an open study, 19 of 20 iron deficient teenage girls felt less tired after 6 weeks. One large trial of 1061 new mothers found no change in tiredness after 4 weeks of oral iron. This dose is above the daily recommended limit, so members can take less. Overall, iron may help fatigue in people who are low in iron, but direct proof of adrenal support is thin. Animal and cell studies are never counted.
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- In 1061 women with anemia after childbirth, oral iron for 4 weeks raised hemoglobin about as much as the herbal formula Ninjin'yoeito, but fatigue did not change with iron and no adrenal measures were reported.A quasi-randomized controlled trial of Ninjin'yoeito for the treatment of postpartum anemia and the prevention of postpa…
- In 737 rural Nepalese pregnant women, cortisol in late pregnancy was 1.3 μg/dL lower only with the multiple micronutrient supplement than with the control; groups receiving iron alone did not show a stated cortisol difference.Antenatal micronutrient supplementation and third trimester cortisol and erythropoietin concentrations.
- In Ghanaian children aged 4-6 years whose mothers took iron and folic acid or a lipid-based supplement in pregnancy, salivary cortisol, hair cortisol and telomere length did not differ between groups.Impact of a nutritional supplement during gestation and early childhood on child salivary cortisol, hair cortisol, and t…
- In 338 people with iron deficiency anemia, intravenous iron improved blood counts and fatigue scores faster than oral iron over 12 weeks, with no adrenal measures reported.[Comparison of the efficacy and safety between high-dose intravenous iron and oral iron in treating iron deficiency anem…
- In 294 newborns of women in Burkina Faso given multiple micronutrients or iron and folic acid during pregnancy, the multiple micronutrients had no overall effect on cord blood hormones including cortisol, though cortisol was 36% higher in first-time mothers' babies.Effect of maternal multiple micronutrient supplements on cord blood hormones: a randomized controlled trial.
- In 85 women with severe fatigue after heavy bleeding at childbirth, a single 1200 mg intravenous iron dose reduced physical fatigue more than oral iron over 12 weeks.Intravenous iron isomaltoside treatment of women suffering from severe fatigue after postpartum hemorrhage.
- In 18 elite male cyclists during a 3-week stage race, 80 mg of iron daily for 4 weeks led to a 13.5% fall in cortisol compared with a 24.7% rise in the control group.Effect of Iron Supplementation on the Modulation of Iron Metabolism, Muscle Damage Biomarkers and Cortisol in Profession…
- In 14 distance runners without iron deficiency, three 100 mg intravenous iron injections over 4 weeks reduced perceived fatigue and mood disturbance compared with saline placebo at 6 weeks.Four weeks of IV iron supplementation reduces perceived fatigue and mood disturbance in distance runners.
- In pregnant women, a combined iron product called Chemiron was linked to a protective effect on placenta insufficiency in the third trimester compared with single iron therapy, according to a preliminary comparison.The effect of combined iron therapy (Chemiron) and single iron therapy on the dexamethasone-estriol reaction test for pl…
- In a single-group trial of 75 pregnant women with iron deficiency anemia, one 1000 mg intravenous iron dose raised hemoglobin by 1.3 g/dL on average and improved fatigue scores.Efficacy of Single-Dose Intravenous Ferric Derisomaltose for Iron Deficiency Anemia in Pregnancy.
- In 20 adolescent girls with iron deficiency and fatigue, intravenous iron sucrose improved fatigue scores at 6 weeks in 19 of 20 girls, and the benefit persisted at 3 and 6 months.Intravenous iron therapy in non-anemic iron-deficient menstruating adolescent females with fatigue.
- Adults with self-reported gluten sensitivity on a gluten-free diet had low dietary iron intake (about 9.6 mg daily) and reported tiredness, but this baseline survey did not test iron supplementation.Dietary and symptom assessment in adults with self-reported non-coeliac gluten sensitivity.
Review Totals and Summary
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Biohacker Summary
Members Only0 of 10 recommend it
0 of 10 biohackers on our panel recommend it
The panel is split on iron, and most of them care more about testing and food than about pills. Four of the ten lean toward recommending it, mainly for people who are low, such as women of reproductive age, pregnant women and young children, and for brain function, thyroid function, hair and muscle recovery. Several favor heme iron from red meat and organ meats over supplements, and one said tea blocks absorption. Caution came up often: half the panel warned that too much iron can cause oxidation, inflammation and faster aging, and that it interacts with copper, so they advise testing before taking it. One panelist said all forms of iron supplements failed to raise his levels over many years, while another takes a supplement and feels less sore after training, and a third uses 10 milligrams of heme iron.
See all 10 biohackers →Hide the biohackers
Dr. Eric Berg · Iron · neutral
- Identifies iron as the Achilles' heel of cancer, as it is needed for its DNA to replicate.
- Mentions that grass-fed liver has heme iron, the most bioavailable form of iron that prevents anemia.
- Dr. Berg warns that too much iron can be damaging to the body and advises focusing on food sources to avoid overconsumption.
- Warns that too much iron, especially the ferrous sulfate or fumarate type found in many supplements, is corrosive and oxidizing, can mess with the liver, and create inflammation, noting that males have no natural way to excrete excess iron.
- Notes that tannins in tea bind iron, blocking its absorption.
- Mentions that vertical ridges on nails could indicate an iron deficiency.
- Discusses iron deficiency and the concern of excess iron accumulation in the body, noting that iron comes from naturally iron-rich foods and can be added to processed foods and supplements.
- Warns that too much iron can increase the risk of type 2 diabetes, liver issues, Parkinson's, and Alzheimer's.
- Recommends consuming food high in iron, such as red meat and organ meats like liver, for women who are menstruating heavily to get their iron.
- Warns that too much iron, typically caused by a genetic issue and more common in men, can be a cause of inflammation.
Dr. Mark Hyman · Iron · neutral
- Mentions iron as an existing biomarker that plays a role in mental health, which Function Health includes in their measurements.
- Notes that a woman patient had very low iron.
- States that they get the whole picture when it comes to iron, looking at ferritin, iron reserves, iron in the blood, iron saturation, and iron binding capacity to spot problems before full-blown anemia.
- Mentions iron as an example of a common nutritional deficiency.
- Notes that many Americans are deficient in iron, which affects mood and brain function.
- Recommends testing Iron as a biomarker before training for fitness.
- States that low iron, specifically a ferritin level less than 45, is a big hidden cause of insomnia, affecting up to half the population.
- Mentions that they check iron levels as part of evaluating mental illness biomarkers.
- Recommends carefully looking at iron, thyroid, and cortisol levels as they all play a role in affecting cognitive function and mental health.
- Mentions that low iron can lead to sleep disruption, even if blood count is normal, and that this is common in physically active people but often unchecked by doctors.
Siim Land · Iron · neutral
- Mentions that iron is a mineral necessary for making collagen.
- States that excess iron promotes oxidative stress and inflammation, which increases heart disease risk.
- Notes that iron deficiency is found in children with premature graying of hair and that some people get gray hair due to iron deficiency.
- Recommends ensuring sufficient iron intake, especially during pregnancy and early life, to prevent mental developmental and cognitive issues.
- States his iron level is 103 micrograms per deciliter, which he considers a good result, and advises that men should aim for lower iron levels to reduce the risk of heart disease and aging.
- Places iron in the 'junk tier', warning that high iron levels are associated with heart disease, mortality, and liver disease, and advises caution with supplementation, especially for men with high iron.
- Warns that high iron levels are associated with increased risk of mortality and reduced lifespan, and that iron in excess is bad for maximum longevity. He states that iron levels slightly on the lower end, around 60 to 90 micrograms per deciliter, are associated with the lowest mortality risk, and that iron below 45 and above 145 micrograms per deciliter is associated with increased risk of mortality.
- Warns that very high iron levels can cause damage to the endothelium and increase the risk of heart disease, especially in men who accumulate iron more easily.
- Warns that too much iron can damage blood vessels, though people with low iron status are safe.
- Theorizes that Brian's lower iron status and hemoglobin status, possibly due to his plant-based diet and lack of iron supplementation, limits his V2 max.
Thomas DeLauer · Iron · neutral
- Compares iron content in spinach (2.7mg) and beef (2.6mg), but emphasizes that beef's heme iron absorbs at about 25%, while spinach's non-heme iron absorbs at 2-8%.
- Recommends iron from meat, specifically red meat and beef liver, stating that it is a crucial part of the mechanistic triad for thyroid hormone function and is iron-dependent for iodine incorporation into thyroid hormone.
- Notes that iron is essential for delivering oxygen to muscles and the brain, making it an important cofactor for signals to reach their targets.
- Recommends assessing iron along with selenium and iodine for optimal thyroid function, suggesting red meat as a source of iron.
- Recommends getting heme iron from real food sources like organ meats, red meats, or pumpkin seeds, and warns against iron supplements due to potential oxidation and issues with copper levels.
- Warns against overdoing iron supplementation unless truly needed, especially if ferritin levels are high, as ferroptosis is iron-dependent and excess iron can increase ferroptotic risk.
- Recommends good quality heme iron from food sources like liver and beef for preventing insulin resistance and type 2 diabetes, supporting glucose control, and energy regulation, but warns against iron supplements.
- States that iron status is critical for white matter development and maintenance, noting that anemic individuals tend to have a loss of white matter structure, which is common in women during perimenopausal transition.
- Warns that polyphenols in coffee can bind to iron, making it useless. He recommends taking iron supplements upon waking on an empty stomach, potentially with vitamin C, and waiting 30-60 minutes before consuming coffee or tea.
- Notes that steak provides heme iron, which is very good for oxygenation of the blood, hemoglobin, and red blood cells.
Andrew Huberman · Iron · recommends
- States that Iron is one of the critical nutrients with the best evidence for cognitive function and reducing the risk of dementia.
- Warns that excess iron will increase the number of senescent cells in the body, which accumulate as people get older and cause inflammation and cancer. He notes that people who are healthy and have a fairly vegetarian diet often have slightly low iron levels but super amounts of energy.
- Notes that about 50% of the population is iron deficient.
- Mentions that the podcast will review the role of iron in treating depression.
- States that B12, folate, and iron are essential to mitochondrial function and if deficient, mitochondria will not function properly, which is consistent with the mitochondrial theory of neuropsychiatric disorders.
- Advises women concerned with low ferritin to take an iron supplement every other day for 10 days, starting on the first day of their bleed, to maximize absorption.
- Discusses the role of iron in hair growth.
- Warns that excess iron, especially as a supplement, can accelerate the aging process by increasing senescent cells in the body.
- Agrees with Mark Hyman that iron is a basic supplement, but warns older men against taking too much due to iron toxicity, while menstruating women need more.
- Recommends that women concerned with low ferritin take an iron supplement every other day, starting at the first day of their bleed, for ten days, to allow for better absorption.
Ben Greenfield · Iron · recommends
- Recommends testing for and replenishing iron if levels are low, as it can affect the ability to maintain or preserve muscle, especially for those on GLP-1s.
- Notes that one can eat iron-rich foods or supplement with iron, but still feel exhausted if iron is not the missing piece, emphasizing that focusing on a single mineral in isolation can support a number on a lab test rather than the system itself.
- Mentions iron as a common deficiency.
- Recommends a nutritious diet including iron, as it is critical for brain development.
- Notes that the guidelines mention iron supplementation for infancy and early childhood.
- Started thinking about getting more heme-based iron in his diet after a podcast about reasons people feel fatigue.
- Warns that modern society has flipped the narrative on iron intake, leading people to consume excessive amounts (20-50 mg) through an iron-fortified diet, which the body cannot assimilate, leading to storage in tissues and disrupting iron physiology, contributing to aging.
- Notes that some people need to supplement with iron, recommending iron biscinate as a form that doesn't irritate the gut.
- Explains that 10X can pinpoint genetic variations that predispose some people to absorbing too much iron and will adjust the iron content in their supplement, potentially reducing or removing it entirely.
- Covers iron as a key supplement for kids.
Bryan Johnson · Iron · stopped
- Has had low iron for 11 years and despite eating meat and trying all forms of iron supplementation at different times and sequences, none of it worked to raise his iron or ferritin levels.
- Had low iron for 11 years, with ferritin averaging 38 ng/mL, and has finally boosted it back to healthy levels.
- Takes 10 milligrams of heme iron to get his iron levels up, as they are borderline.
- Recommends adequate Iron for hair health, noting it is in the Blueprint stack.
- Recommends supplementing with iron for brain health for both the mother and the baby during pregnancy.
Dave Asprey · Iron · warns
- Warns that if a doctor diagnoses anemia, one should not assume they just need more iron, as low hemoglobin doesn't always mean low iron and the issue can sometimes be how well the body is using iron.
- Notes that when energy intake is too low for training demand, nutrient intake often falls short, especially for iron, which is associated with impaired recovery.
- Recommends ensuring iron levels are good as it is a cofactor that can help thyroid function, especially with conversion issues.
- Egg yolks, particularly raw egg yolks, fatty cuts of meat, choline sources like that, making sure there's enough iron and a lot of the micro minerals, trace minerals, things like that. Those would be really important for bone marrow because mineral deficiencies are going to block that at the start.
- Warns that both too much and not enough iron can trash the body, highlighting the complex interactions between iron and copper.
- States that iron really helps in maintaining hair growth.
- States that many vegans don't get enough iron, which slows metabolism and makes it harder to build muscle.
- Warns that low iron in women leading up to and through the first 30 weeks of pregnancy can result in the baby having a lower IQ and being more likely to have ADHD and demyelination issues.
- Advises taking iron and calcium separately because they will bind together.
- Advises getting iron levels up through diet and supplementation, and to take iron and calcium separately because they will bind together.
Dr. Rhonda Patrick · Iron · uses
- Recently found out he needed to get on an iron supplement and noticed he gets less sore in his training after taking it.
- Advises that menstruating women should ensure they are getting enough iron.
- Warns that iron is not an innocuous supplement and should not be taken aggressively without proper testing, as it can be complicated and has significant downsides if levels are not understood.
- Dr. Patrick explains that breast milk is incredibly low in iron, and by six months, infants can develop iron deficiency anemia, so pediatricians recommend introducing iron-rich complementary foods at that time.
- Rhonda discusses Dr. Lithgow's work on how excess dietary iron affects protein homeostasis in worms, noting that increased iron levels in the diet accelerated aging and the accumulation of insoluble proteins.
- Dr. Patrick takes some iron during menstruation.
- Increased iron levels in the brain worsen cognitive test performance by as much as 10% in older adults, a phenomenon linked to brain atrophy and decline in memory and attention.
- Iron plays a central role in health across the lifespan. It forms the core of hemoglobin, the molecule in red blood cells...
- The requirement for iron is 1.8 times higher for vegetarians.
- The findings highlight the importance of proper nutrition during development and suggest that iron supplementation may be beneficial, especially during adolescence.
Peter Attia · Iron · recommends
- Recommends iron supplements for women of reproductive age who are iron deficient.
- Notes that deficiencies in certain vitamins and minerals, such as iron, can be a cause of hair loss in women.
- Delves into the crucial yet often overlooked topic of iron and iron deficiency.
- Explains that humans consume about 10 to 20 milligrams of iron per day, absorbing roughly 10% of that, which is 1 to 2 milligrams per day, perfectly offsetting the 1 to 2 milligrams lost daily.
- Peter emphasizes the importance of consuming an adequate amount of iron daily to prevent deficiency.
- Speculates that lower iron levels in women due to their menstrual cycle may offer a protective benefit against heart disease, citing data that metabolically deranged men benefit from therapeutic phlebotomy.
RAL Summary
Members OnlyTier 4 for Adrenal Support
Only one small trial in 18 cyclists showed lower cortisol with iron, larger pregnancy trials showed no cortisol change, and there are no reviews, so the evidence is emerging.
- Emerging: not enough evidence to rank higher yet.
Where the evidence disagrees: 4 of the 12 human studies found no effect.
More Details
Members OnlyBody systems · Combine with · Possible side effects
Body systems: Endocrine system, Blood
Possible side effects: No major side effects reported.
Supplement Facts
Iron 65 mg
Other ingredients: Cellulose Gel, Dibasic Calcium Phosphate, Croscarmellose Sodium, Hypromellose, Color added, Magnesium Stearate, Polyethylene Glycol, Triethyl Citrate, Polysorbate 80.
Directions: Suggested Use: Adults with iron deficiency, take 1 tablet daily with water and a meal.
Barcode (UPC) 031604031756 · Label source: NIH label database · Report a label change
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Graded November 6, 2026 by the Reverse Age Lab evidence engine, from human studies, real reviews and our biohacker panel. How we grade. Is this medical advice? No. Rala organizes the published evidence; go over any change with your doctor, especially if you take meds.
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