ChromiumMineral

• Blood sugar in type 2 diabetesPossibly helps

  The most-cited result is a 1997 RCT in 180 adults with type 2 diabetes. At 1,000 mcg/day of chromium picolinate for 4 months, mean fasting glucose was 128 mg/dL against 159 mg/dL on placebo, and HbA1c 6.6% against 8.5% [1].
  
  A 2019 review of 8 meta-analyses covering 58 trials found only a slight lowering of fasting glucose and HbA1c overall, of unclear clinical significance [1]. Other individual RCTs found no significant effect on insulin sensitivity at all.
  
  The official bodies are unconvinced. The American Diabetes Association does not recommend chromium for diabetes or obesity, and the FDA's qualified health claim for chromium picolinate and insulin resistance calls the evidence highly uncertain [1]. ^[1]

• Weight and body compositionPossibly helps

  A 2019 meta-analysis of 21 trials in 1,316 participants found chromium produced 0.75 kg more weight loss than placebo, a 0.40 kg/m² larger BMI drop, and 0.68% more body-fat reduction [1].
  
  Waist circumference did not change significantly, and nothing in that pooling supports a distinct muscle-building effect [1].
  
  Those numbers are statistically significant and practically tiny. A 2013 Cochrane review called the clinical relevance debatable, on low-quality evidence [1]. ^[1]

• PCOSPossibly helps

  Several meta-analyses of chromium in PCOS, mostly picolinate at 200–1,000 mcg/day, found no significant effect on fasting glucose or on several hormone levels [1].
  
  Some of the same analyses did find small reductions. One pooling of 7 trials in 351 participants reported a 2.37 kg/m² BMI reduction, alongside smaller drops in free testosterone and fasting insulin [1].
  
  The authors themselves describe the effect size as small and of uncertain clinical relevance. ^[1]

• Metabolic syndromePossibly helps

  Few trials exist here, and the ones that do found no meaningful benefit on glycemic, lipid, or weight measures [1].
  
  Read that as a thin evidence base returning nothing, rather than as a well-powered null result. ^[1]

• Blood lipidsPossibly helps

  Individual trials show no consistent effect on total or LDL cholesterol [1].
  
  Meta-analyses in diabetes and PCOS populations found HDL up by roughly 1.7 to 4.6 mg/dL and triglycerides down by roughly 11.7 to 26.6 mg/dL [1]. Those are narrow shifts on markers that swing far more with diet and body weight. ^[1]

• Appetite and carbohydrate cravingsPossibly helps

  One 8-week trial gave healthy overweight women 1,000 mcg/day of chromium picolinate [5].
  
  They reported less food intake, less hunger, and fewer cravings for carbohydrates, fast food, high-fat food and sweets [5].
  
  That is a single small study on self-reported outcomes. Take it as preliminary. ^[5]

• Chromium picolinateThe form used in most clinical trials, so it is what the evidence actually covers .

  Elemental content

  Elemental chromium is only 12.4% of the compound's weight; labels state the elemental amount, not the compound weight

  Absorption

  About 1.2% of an oral dose, per NIH's Office of Dietary Supplements [1].
  
  ODS calls absorption broadly similar across supplement forms. A 2007 human trial (DiSilvestro and Dy) disagreed, finding picolinate gave roughly 50% higher 24-hour urinary chromium than the next-best form tested [3].

  Best for

  The form used in most clinical trials, so it is what the evidence actually covers [1].

• Chromium nicotinate and polynicotinateNothing the human data singles it out for.

  Elemental content

  Chromium bound to nicotinic acid; elemental share varies by product and is stated on the label

  Absorption

  Ranked below picolinate in the 2007 human urinary-recovery trial [3].
  
  EFSA cites earlier rat studies with the opposite ranking, where nicotinate was retained better than picolinate [4]. Human and animal data disagree here, and the disagreement has not been resolved.

  Best for

  Nothing the human data singles it out for. It is a common multivitamin ingredient [3].

• Chromium chlorideMultivitamin and mineral products, where it is the cheap default .

  Elemental content

  The simplest trivalent salt; elemental chromium is stated on the label

  Absorption

  About 0.4% of an oral dose, per NIH ODS — the low end of the roughly 0.4% to 2.5% range across all forms and food [1].
  
  That is similar to what is absorbed from food generally.

  Best for

  Multivitamin and mineral products, where it is the cheap default [1].

• Chromium histidinateNo use the reviewed sources support over the better-studied forms .

  Elemental content

  Chromium bound to the amino acid histidine

  Absorption

  Sold as a supplement form, but no absorption figure for it appears in the sources reviewed here [1].
  
  Do not assume it matches picolinate.

  Best for

  No use the reviewed sources support over the better-studied forms [1].

• Serious case reports at high intakes

  Chromium is usually well tolerated, but isolated case reports at high intakes — mostly picolinate — describe real harm [1].
  
  Reported: weight loss, anemia, thrombocytopenia, liver dysfunction, renal failure, rhabdomyolysis, dermatitis and hypoglycemia [1].
  
  Warning signs of the liver reactions include nausea, upper abdominal pain, itching, dark urine and jaundice [6]. ^[1]

• Common, milder effects

  The routinely reported ones are headache, insomnia, and mood changes or irritability [1].
  
  Rarer reactions include problems with thinking, concentration, balance or coordination [6]. ^[1]

• Kidney or liver disease

  NIH's expert panel flagged that people with renal or liver disease may be more susceptible to adverse effects from high chromium intakes [1].
  
  The kidneys are chromium's main excretion route. Drug-reference sources list kidney disease as a reason to talk to a doctor first [6]. ^[1]

• Pregnancy and breastfeeding

  Adequate Intakes exist for chromium from food during pregnancy and lactation, but that is not a clearance for supplements [2].
  
  Whether supplemental chromium affects pregnancy or a developing fetus is not known, and chromium does pass into breast milk [2].
  
  Drug-reference sources advise against using chromium supplements in either state without medical guidance [6]. ^[2]

• Chromium allergy and leather cross-sensitivity

  Allergic reactions appear uncommon but can be serious: breathing problems, swelling of the face, lips, tongue or throat, hives and dizziness, all needing immediate care [6].
  
  People allergic to chromium or chromic chloride should avoid it. One drug-reference source also lists allergy to leather products, a chromium-tanning cross-sensitivity, as a contraindication [6]. ^[6]

• Corticosteroids and a high-sugar diet

  Drug-reference guidance cautions against combining chromium with corticosteroids such as prednisone or fluticasone [6].
  
  The same guidance suggests a high-sugar diet may reduce chromium picolinate's effectiveness, though the size of that effect is not quantified [6]. ^[6]

• Insulin and other antidiabetes drugs

  Chromium may increase insulin sensitivity, so taking it with insulin raises the risk of hypoglycemia [1].
  
  The same additive glucose-lowering applies to metformin and other antidiabetes medications [2]. ^[1]

• Levothyroxine

  A small study found chromium picolinate taken at the same time as levothyroxine reduced levothyroxine absorption over a 6-hour window [1].
  
  The two are generally recommended to be spaced apart [2]. ^[1]

• Antacids, vitamin C and aspirin

  Antacids inhibit chromium absorption [1].
  
  Ascorbic acid (vitamin C) and prostaglandin inhibitors such as aspirin appear to increase it [1]. Neither direction has been quantified in the sources reviewed here. ^[1]

Chromium is spread thinly across many foods, and published values are only a rough guide — measured content in oatmeal samples has varied by up to 50-fold depending on soil, water and processing [1].

The better per-serving sources: grape juice 7.5 mcg per cup (21% DV), ham 3.6 mcg per 3 oz (10% DV), a whole-wheat English muffin 3.6 mcg (10% DV) [1].

Then brewer's yeast 3.3 mcg per tablespoon (9% DV), orange juice 2.2 mcg per cup (6% DV) and beef 2.0 mcg per 3 oz (6% DV) [1].

Most everyday items — apples, bananas, whole-wheat bread, chicken, rice, vegetables — land at roughly 0.3–1.4 mcg per serving, 1 to 4% of the Daily Value [1].

Most dairy products and foods high in added sugar are low in chromium [1]. Human milk averages about 0.25 mcg/L, though small European studies reported anywhere from 0.14 to 10.8 mcg/L.

No trial has established an optimal time of day, and NIH's fact sheets give no timing guidance beyond the levothyroxine issue [1].

The one evidence-based rule is spacing: keep chromium away from levothyroxine, which absorbs less well over roughly a 6-hour window when the two are taken together [1]. Antacids should also be kept apart from a chromium dose, since they inhibit its absorption.

Human absorption studies gave chromium alongside a small standardised meal as a matter of protocol [3]. Pairing it with food is common practice for reducing stomach upset, not a finding about effectiveness.