Chromium

Chromium is a metal that appears in food and supplements as chromium(III), also called trivalent chromium. The NIH (the US National Institutes of Health) says it may play a role in carbohydrate, fat and protein metabolism. It may do this by strengthening the action of insulin, including how the body handles glucose.

In blood, most of it rides on transferrin, the iron-carrying protein. It settles mainly in the liver, spleen, soft tissue and bone.

The US sets an adequate intake, a target used when data are too thin for a firmer target. It is 35 µg (micrograms) a day for men and 25 µg for women aged 19 to 50, which matches what well-balanced diets contain. Chromium is one of the trace minerals, and the supplement form studied most often is chromium picolinate.

Here is what most readers do not know: whether chromium is an essential nutrient at all is disputed. In 2014 the European Food Safety Authority (EFSA) found no evidence of beneficial effects of chromium intake in healthy people. It decided that setting an adequate intake was not appropriate. The US value from 2001 still stands.

A 2010 review says chromium pills became very popular for weight loss and muscle building. Their sales were second only to calcium among mineral supplements.

Do not confuse it with chromium(VI), the hexavalent form. The NIH calls it a toxic by-product of stainless steel and other manufacturing. The US Institute of Medicine says it is not found in food.

Only about 0.4% to 2.5% of the chromium in food is absorbed. So a balanced diet gives the body about 0.15 µg a day, the NIH estimates.

Health benefits of chromium

• ★★★EU allows claims on glucose and metabolismThe EU food safety agency based them on glucose intolerance in the few known cases of chromium depletion. It found no evidence of benefit in healthy people.
• ★★Slightly lower HbA1c in type 2 diabetesAcross 25 trials, chromium supplements lowered HbA1c, a measure of average blood sugar, by 0.55%. Trials disagreed widely, and a US review rated the evidence low and saw little reason to recommend chromium.
• ★★A very small weight loss, of unclear importanceAcross 21 trials in adults with overweight or obesity, chromium supplements added 0.75 kg of weight loss over placebo. A Cochrane review of chromium picolinate found 1.1 kg, rated low-quality evidence.
• ★No clear change in insulin sensitivityIn people with type 2 diabetes, 1,000 µg of chromium a day did not consistently improve insulin sensitivity. In 63 people with metabolic syndrome, it did not change it over 16 weeks.
• ★No clear help for atypical depressionIn 113 adults, 600 µg of chromium a day did not beat placebo on the main depression scores over eight weeks. A pilot of 15 people had found 7 of 10 responded on chromium.

Foods high in chromium

Dates lead the per-serving ranking below: two dates (48 g) hold 38.4 µg. That is 110% of the 35 µg Daily Value, the FDA label amount. Soybeans and mung beans are not ranked, because we hold no chromium value for the cooked beans. A cup of lentils follows dates with 17.8 µg, then 3 oz of oysters (10.5 µg) and a tablespoon of cocoa powder (9.3 µg).

Per 100 g, cocoa powder leads at 173 µg, then dates (80 µg), dill (20.3 µg) and sesame seeds (12.5 µg).

Treat these values as a guide. The NIH says chromium is hard to measure in food because samples are easily contaminated. Its own table lists much lower amounts, such as 7.5 µg in a cup of grape juice. Ham (3 oz) or a whole-wheat English muffin has 3.6 µg, brewer’s yeast 3.3 µg per tablespoon and beef 2.0 µg per 3 oz.

Chromium in the same food can vary 50-fold with soil, water and processing, as in oatmeal. Most dairy and sugary foods are low. Meats, grains, fruits, vegetables, nuts, spices, brewer’s yeast, beer and wine all contain some.

Cookware adds to it. In a laboratory test, tomato sauce cooked for 6 hours in stainless steel picked up up to 7 times more chromium. By the tenth cooking cycle, a 126 g serving carried 86 µg from the pot. Because only a small share is absorbed, a high number on the page does not mean a high dose reaches the body.

How chromium works

Most of what is known about how chromium might work comes from test tubes, rats and reviews, not from trials in people. The main idea is contested. Four points cover it.

Chromium is proposed to amplify the signal of insulin, and very little of it is absorbed. Experts disagree on whether the body needs it. And the chromium(III) in food is a different substance from toxic chromium(VI). Here is each one, and what has been seen in people.

It is proposed to amplify insulin’s signal

The NIH says chromium might strengthen insulin’s action, but the precise mechanism has not been identified. The leading idea is a small chromium-binding peptide called chromodulin. A 2000 review describes it as binding chromium ions when insulin sets them moving. It then attaches to an insulin-activated insulin receptor and switches on its tyrosine kinase activity, which would amplify the signal.

In rats, transferrin carried chromium in the blood, insulin sped up that transport, and chromium left in urine as chromodulin. A 2015 review asks whether chromium works as a “second messenger” and proposes tests for the idea.

EFSA’s 2014 panel still judged that the mechanisms and the essential function had not been substantiated. In obese, insulin-resistant rats, chromium picolinate raised insulin signaling in muscle (see the rat study above).

Very little is absorbed

The NIH puts absorption of dietary chromium at about 0.4% to 2.5%. In 32 adults eating their usual diets for a week, absorption fell as intake rose. It went from about 2% at 10 µg a day to 0.5% at 40 µg. Vitamin C and aspirin-type drugs raise absorption, while oxalate and antacids lower it, according to the NIH.

Chromium leaves mainly in urine. So urinary chromium follows recent intake and says little about body stores. The NIH says no validated way of judging chromium status exists.

Is it essential? The experts disagree

The US panel that set the adequate intake in 2001 had too little data for an average requirement. So it based the value on what healthy people eat. EFSA looked at the same question in 2014 and decided the case for essentiality was not made.

The NIH notes that recent research has suggested chromium is not an essential mineral. That is because an absence or deficiency does not produce abnormalities that adding chromium reverses. It might still have benefits at pharmacologic (drug-like) amounts in the hundreds of µg.

In rats raised in metal-free cages for 6 months, a diet with as little chromium as possible changed nothing measured. The study’s last author, Vincent, wrote in 2017 that chromium can only be considered pharmacologically active. He has reported being an inventor or co-inventor on 7 patents involving chromium supplements or therapeutic agents.

On the other side is a study of 17 adults fed controlled diets in the lowest quarter of normal chromium intake. With 200 µg of chromium a day, glucose tolerance improved in the group with mildly impaired tolerance and did not change in the others.

Chromium(III) and chromium(VI) are different substances

Food and supplements contain chromium(III). The Institute of Medicine says chromium(VI) is far more toxic and is not found in food. It says swallowed chromium(III) has low toxicity partly because it is absorbed so poorly. Chromium(VI) is a human carcinogen (it causes cancer) when inhaled.

In two-year US National Toxicology Program studies, chromium(VI) in drinking water caused rare mouth tumors in rats and small intestine tumors in mice. In rats, much more chromium reached the tissues after chromium(VI) than after similar doses of chromium(III). That is because some chromium(VI) escapes conversion to chromium(III) in the stomach.

A 2006 review reported that 38% of municipal drinking water sources in California had detectable chromium(VI). It concluded that oral exposure appears to pose a cancer risk.

A separate question is whether chromium(III) supplements can turn into chromium(VI) in the body. A 2008 chemistry review argues that, in laboratory reactions with biological oxidants, these supplements form reactive chromium(VI), chromium(V) and chromium(IV) species. It calls for the safety of picolinate to be reconsidered. That remains a laboratory argument, and the section on forms below sets it beside EFSA’s opinion.

What has been seen in people

The clearest human finding is about deficiency. A few patients fed by vein for years improved when chromium was added, though the NIH says the feeding solutions were not properly measured. In type 2 diabetes, the average gain in HbA1c is 0.55 to 0.71 percentage points across meta-analyses, and trials disagree strongly. A review found no benefit in people without diabetes.

In the trial that looked at who responds, responders had lower insulin sensitivity and higher glucose and HbA1c at the start. Weight loss averages 0.5 to 1.1 kg. A mechanism built on insulin would fit that pattern, but it remains unproven, as the study cards above show.

How much chromium do you need?

The US adequate intake for chromium is 35 µg a day for men and 25 µg for women aged 19 to 50. After age 50 it is 30 µg and 20 µg. The EU sets no intake value, because EFSA concluded in 2014 that setting an adequate intake for chromium is not appropriate.

The US panel could not set an average requirement, so its adequate intake describes what healthy people eat. It took 13.4 µg per 1,000 kcal, the mean of 22 well-balanced diets designed by nutritionists. It multiplied that by 2,800 kcal for men and 1,850 kcal for women aged 19 to 30. That gives 35 and 25 µg.

The panel used these highest energy values to allow for under-reporting of food. After 50 the values fall with energy intake, because the panel used 2,100 and 1,500 kcal for men and women aged 50 to 70. In other words, the number measures typical intake, not a proven need.

In pregnancy the US values are 29 µg a day at ages 14 to 18 and 30 µg from 19 to 50. While breastfeeding they are 44 and 45 µg. The panel added 20 µg to a woman’s value to replace chromium lost in milk, assuming that 1% is absorbed.

People in US studies eat about this much. In one study of self-selected diets, 10 men averaged 33 µg a day and 22 women averaged 25 µg. The NIH says most people in the US have intakes similar to the adequate intakes. Chromium is not covered by the national nutrition survey, so there are no national figures.

Labels use a Daily Value of 35 µg in the US and an EU Reference Intake of 40 µg.

Chromium deficiency: signs and who is at risk

Chromium deficiency has not been reported in healthy people, and the NIH says no definitive deficiency symptoms have been established. The only reports are three from the 1970s and 1980s, in patients fed by vein for years (total parenteral nutrition). They had high blood sugar, sugar in the urine, unexplained weight loss, nerve damage, glucose intolerance or confusion, which eased with chromium.

EFSA called this the most convincing evidence but said it could not identify a requirement. The NIH adds that the feeding solutions were not adequately measured, so the reports do not show that healthy people can become deficient. Today’s intravenous solutions routinely get 10 to 15 µg a day, much more than the 0.15 µg a day a balanced diet supplies.

• Who is at risk. The only group with reported cases is people on long-term intravenous feeding. We found no other group shown to be at risk.
• Testing. No validated test and no clinically defined deficiency state exist. Urinary chromium follows recent intake, and hair levels might reflect past intake. In one patient with high blood sugar on intravenous feeding, plasma chromium stayed the same after treatment worked. Her doctors cautioned about reading blood levels.

Forms of chromium: absorption and effects

Chromium supplements come as chromium picolinate, nicotinate, polynicotinate, chloride, histidinate and chromium-enriched yeast, the NIH says. The label lists elemental chromium, not the weight of the compound. The NIH puts chromium at 12.4% of the weight of chromium picolinate. Forms differ in chemistry, but the body absorbs only a small share of any of them, so dose probably matters more than form.

The honest bottom line is that we found no head-to-head trial of forms for a health outcome. Studies that compare absorption disagree. The NIH says absorption of the various forms is similar, while a small urine study found histidinate absorbed better than picolinate.

A radiotracer study found picolinate no more retained than another complex after 7 days. Published estimates for picolinate run from about 1% to 5%, the top of the range coming from the FDA’s 2005 review. Claims that picolinate, nicotinate or histidinate works better for blood sugar or weight loss have no head-to-head trial behind them. Picolinate is also the form with the most safety questions, covered in the safety section below.

The forms used in the main outcome trials above were:

• Blood sugar trials. Picolinate in the 1997 trial, the Kleefstra trial and the metabolic syndrome trial. A meta-analysis that split 14 trials by form had chloride in 3, picolinate in 5, brewer’s yeast in 4 and chromium yeast in 3. One meta-analysis saw glucose effects especially with picolinate. The form-by-form analysis below found no clear HbA1c effect for picolinate or chromium yeast.
• Weight loss trials. The Cochrane review covered chromium picolinate only. Per the NIH, most trials in the 21-trial analysis used picolinate, and others used chromium-enriched yeast or nicotinate.
• PCOS and depression trials. Chromium picolinate in the PCOS meta-analysis as the NIH describes it, and in both depression trials.

Form	Share of chromium by weight	What studies show	Source
Chromium picolinate	12.4%	The most studied form and the one used in most trials above. Absorption is about 1.2% according to the NIH, 2.80% from urine modeling in volunteers, and 0.8% to 1% in a radiotracer test, where most of it left in urine. EFSA found it not of concern up to 250 µg a day of total chromium. In hamster cells it was more mutagenic than chromic chloride.	1, 2, 3, 6, 7, 13
Chromium chloride	not stated	Absorption is about 0.4% according to the NIH. In the form-by-form analysis, 3 chloride trials showed no effect on fasting glucose. In hamster cells it raised mutants 10-fold, against 40-fold for picolinate.	1, 5, 6
Chromium nicotinate and polynicotinate	not stated	Used in some weight loss trials per the NIH. Rats absorbed 0.04% to 0.24% of the chromium, like the other forms tested. We found no human absorption comparison. One case report of toxic hepatitis involved polynicotinate taken with plant extracts.	1, 2, 11
Chromium-enriched yeast and brewer’s yeast	not stated	In the form-by-form analysis, chromium yeast did not change HbA1c or fasting glucose, while brewer’s yeast lowered fasting glucose by 19.23 mg/dL with no HbA1c effect. A trial in 70 people with metabolic syndrome and impaired glucose tolerance found no change in glucose or lipids; one author is employed by Pharma Nord.	5, 9
Chromium histidinate	not stated	In 6 adults, urinary chromium after 200 µg was higher than after picolinate (3,670 against 2,082 ng a day), which suggests better absorption. We found no human trial of histidinate for a health outcome. Most other work is in animals, including a rat study with an author at Nutrition 21.	4, 10

Safety differences between forms rest on thin evidence. EFSA’s 2010 food additives panel found chromium picolinate not of concern in fortified foods and supplements, up to 250 µg a day of total chromium. That is the WHO value for supplemental intake.

It noted that new genotoxicity studies suggest picolinate might damage DNA in test tubes at high concentrations. It found equivocal evidence of cancer activity in male rats, and none in female rats and in mice. No trial has compared side effects of one form with another.

A 2000 review adds that chromium from picolinate enters cells by a different route from ionic chromium. Releasing it requires reducing the chromium, a step that could in principle produce harmful hydroxyl radicals. A 2008 chemistry review singles out picolinate for concern about genotoxicity.

Is chromium safe? Supplements, dose and interactions

Chromium from food is not a concern for most people. The US panel set no tolerable upper intake level for chromium. It found insufficient data for soluble chromium(III) salts, and no adverse effects convincingly linked to high intakes from food or supplements. It noted that this does not rule out harm and that caution may be warranted.

The NIH adds that people with kidney or liver disease might be susceptible. In the EU, EFSA’s 2010 opinion found chromium picolinate not of concern if total chromium stays at or below 250 µg a day. Supplement doses can be far above that. Multivitamins typically hold 35 to 120 µg, chromium-only pills commonly 200 to 500 µg, and some up to 1,000 µg.

• Doses and side effects. Trials used 200 to 1,000 µg of picolinate a day. Reported side effects included watery stools, vertigo, headaches and hives (urticaria), and a meta-analysis found no higher risk than with placebo at usual doses. In the Cochrane review, only three of nine studies reported adverse events. There were serious events in people taking 1,000 µg (two) and 400 µg (one), and one in a placebo participant.
• Kidney and liver case reports. A 33-year-old woman took 1,200 to 2,400 µg of chromium picolinate a day for 4 to 5 months. She had anemia, low platelets, hemolysis (red cell breakdown), liver dysfunction and kidney failure, needed dialysis, and had normal tests a year later. Another case of acute tubular necrosis involved a multi-ingredient product that also held Sida cordifolia, synephrine and guarana, in a man with a single kidney. A case of toxic hepatitis involved chromium polynicotinate taken with plant extracts for 5 months. The NIH lists weight loss, anemia, low platelets, liver dysfunction, kidney failure, muscle breakdown (rhabdomyolysis), dermatitis and low blood sugar among isolated case reports. Case reports cannot prove cause.
• Diabetes medicines and thyroid pills. Chromium might increase insulin sensitivity. So taking it with insulin could raise the risk of low blood sugar, and it might add to metformin and other diabetes drugs. A small study found chromium picolinate taken at the same time as levothyroxine decreased levothyroxine absorption over 6 hours, the NIH says.
• DNA damage in the lab. Cell studies show picolinate can damage DNA at high concentrations. A chemistry review worries that chromium(III) supplements can form reactive chromium(VI) in the body. EFSA’s panel still judged picolinate not of concern up to 250 µg a day. The effect in people is not known.
• Who should ask a doctor first. People with kidney or liver disease, and people taking insulin, other diabetes medicines or levothyroxine. Also anyone considering trial-level doses, which are up to 40 times the adequate intake for women.

How to get more chromium

• Best foods. In our ranking, two dates give 38.4 µg, a cup of lentils 17.8 µg and 3 oz of oysters 10.5 µg. The NIH table lists far lower amounts, for example 7.5 µg in a cup of grape juice and 3.6 µg in 3 oz of ham.
• Eat a varied diet. Well-balanced diets contained about 13.4 µg per 1,000 kcal in the study behind the US value. Adults in US studies ate about 25 to 35 µg a day. Most dairy and sugary foods are low in chromium.
• Food over pills. EFSA found no evidence of benefit from chromium intake in healthy people, and the pooled supplement effects in diabetes are small. If you take a supplement, the label shows elemental chromium. The amounts in multivitamins (35 to 120 µg) are at or above the adequate intake.

History of chromium

About 60 years ago, chromium was proposed as an essential element for mammals, with a role in carbohydrate and lipid metabolism. A 1959 paper by Schwarz and Mertz was titled “Chromium(III) and the glucose tolerance factor”. For decades it was treated as a trace nutrient that supports insulin.

In 1977 a Toronto team reported a woman on years of intravenous feeding whose glucose intolerance and nerve damage improved with chromium. It was the first of three such reports, and in 2001 the US Institute of Medicine set adequate intakes.

Meanwhile supplements took off: a 2010 review says chromium pills became very popular for weight loss and muscle building. Their sales were second only to calcium among mineral supplements. In 2005 the FDA allowed one heavily qualified claim for chromium picolinate. In 2012 the EU listed two permitted claims for chromium on foods, based on an EFSA opinion from 2010.

Then the doubts grew. A 2011 rat study found no effect of a very low chromium diet, and EFSA decided in 2014 that no intake value could be set. A 2017 review argued chromium should be seen as pharmacologically active rather than essential. The NIH notes that the US National Academies have not reviewed chromium since 2001.

Frequently asked questions about chromium

Is chromium an essential mineral?

It depends on who you ask. The US National Academies set an adequate intake in 2001: 35 µg for men and 25 µg for women aged 19 to 50. In 2014 EFSA found no evidence of beneficial effects of chromium intake in healthy people and set no value. The NIH says deficiency has been reported only in a few patients on long-term intravenous feeding. Those reports did not measure the feeding solutions well. In rats on a very low chromium diet for 6 months, glucose tolerance and insulin sensitivity did not change.

Does chromium picolinate help with blood sugar?

Slightly on average, and not for everyone. In type 2 diabetes, meta-analyses found HbA1c 0.55 to 0.71 points lower, but trials disagreed (heterogeneity 99.8% for glucose in one). The form-by-form analysis found no clear HbA1c effect for picolinate. In a review of 20 trials, only 3 of 14 reached an HbA1c goal. A review found no benefit without diabetes, and the FDA calls a link to insulin resistance highly uncertain. If you take diabetes medicine, ask your doctor first, because chromium could add to its effect.

Does chromium help you lose weight?

Only a little, if at all. The Cochrane review found 1.1 kg more weight loss than placebo after 12 to 16 weeks of chromium picolinate, of debatable clinical relevance. The evidence was low-quality, and a 21-trial analysis found 0.75 kg and another review 0.5 kg. In 2010 EFSA judged the evidence insufficient to support a claim on normal body weight. Trials were short, up to 24 weeks, so long-term effects are unknown.

How much chromium picolinate should you take a day?

No dose has been proven to help. The adequate intake for adults aged 19 to 50 is 25 to 35 µg, and picolinate trials used 200 to 1,000 µg a day. The US panel set no upper limit because data were thin. EFSA’s 2010 opinion on picolinate found no concern if total chromium stays at or below 250 µg a day. A woman who took 1,200 to 2,400 µg a day for 4 to 5 months had kidney failure and liver problems. Ask your doctor before taking trial-level doses.

What are the side effects of chromium picolinate?

In trials, reported side effects included watery stools, vertigo, headaches and hives (urticaria). A meta-analysis found no higher risk than with placebo at usual doses. Rare case reports describe kidney failure, liver injury, anemia, low platelets, muscle breakdown and low blood sugar at high doses. The NIH says people with kidney or liver disease might be susceptible, and chromium might add to the effect of insulin and other diabetes drugs.

Which foods are highest in chromium?

Per serving, our ranking is led by two dates (38.4 µg) and a cup of lentils (17.8 µg). Then come 3 oz of oysters (10.5 µg) and a tablespoon of cocoa powder (9.3 µg). The NIH’s own table lists lower amounts, for example 7.5 µg in a cup of grape juice and 3.6 µg in 3 oz of ham. It says food values vary widely, so treat all of these as a guide.

Are chromium and vanadium good for diabetes?

We found no randomized trials of chromium and vanadium taken together in PubMed, only small studies of vanadium alone. In one single-blind study, 8 people with type 2 diabetes took 50 mg of vanadyl sulfate twice a day. Over 4 weeks, fasting glucose fell by 20%. But 6 of the 8 had stomach side effects in the first week. The authors said the safety of larger doses and longer use was uncertain.

Is chromium in supplements the same as the toxic chromium in drinking water?

No. Food and supplements contain chromium(III). The toxic form is chromium(VI), an industrial by-product that the Institute of Medicine says is not found in food. In US National Toxicology Program studies, it caused tumors in rats and mice when given in drinking water. A laboratory review argues that chromium(III) supplements can form reactive chromium(VI) in the body. But EFSA judged chromium picolinate not of concern up to 250 µg a day.