Chromium and Human Health: Different Forms, Different Effects
Trivalent chromium (Cr III) is an essential trace element that is safe at recommended intake levels, while hexavalent chromium (Cr VI) is carcinogenic and toxic to humans. 1
Forms of Chromium and Their Effects
Trivalent Chromium (Cr III)
- Essential micronutrient: Functions as a component of metalloenzymes
- Biological roles:
- Enhances insulin action in peripheral tissues
- Intervenes in metabolism of carbohydrates, protein, and fat
- Increases insulin receptors and activates glucose transporters Glut1 and Glut4 1
- Absorption: Low bioavailability (0.4-2.5%) in small bowel 1
- Daily needs: Adequate intake is 35 μg/day for men and 25 μg/day for women 1
- Food sources: Mainly high-bran cereals 1
Hexavalent Chromium (Cr VI)
- Toxic form: Confirmed human carcinogen 2, 3
- Sources: Industrial processes, metal plating, dyes, paint pigments, leather tanning 2
- Health effects:
- Powerful epithelial irritant
- Lung carcinogen (sufficient evidence for inhalation and lung cancer) 4
- Can act as oxidant directly on skin or be absorbed through damaged skin 2
- Causes prooxidative effects, inhibits antioxidant enzymes 2
- Acts as hematotoxic, immunotoxic, hepatotoxic, pulmonary toxic, and nephrotoxic agent 2
Health Implications
Deficiency of Trivalent Chromium
- Insufficient intakes are common in industrialized countries 1
- Associated with alterations in glucose metabolism, especially in older adults 1
- Clinical manifestations include:
- Glucose intolerance
- Weight loss
- Elevated plasma free fatty acids
- Neuropathy 1
- Populations at risk:
- Patients with acute illness due to metabolic stress
- Patients with decreased absorption/intake (short bowel syndrome)
- Patients on parenteral nutrition without chromium supplementation 1
Toxicity Concerns
- Hexavalent chromium (Cr VI) is a known carcinogen with genotoxic properties 4, 5
- Trivalent chromium (Cr III) has low toxicity and a broad safety range 6
- The human body has effective detoxification mechanisms that can reduce ingested or inhaled Cr(VI) to Cr(III) 6
- No reported cases of chromium toxicity in adults on long-term parenteral nutrition despite high chromium levels 1
- Chromium toxicity may be more concerning in pediatric patients 1
Clinical Applications
Supplementation Recommendations
- For general population: Not recommended for improving glycemia or dyslipidemia control in patients with type 2 diabetes, obesity, or non-diabetic patients 1
- For parenteral nutrition: 10 μg per day is sufficient 1
- For enteral nutrition: Should provide at least 35 μg/day with 1500 kcal/day 1
Special Clinical Scenarios
- In critically ill patients with severe insulin resistance: A therapeutic trial with IV chromium (3-20 μg/h for 10 hours up to 4 days) can be used to reduce insulin requirements 1
- In patients on parenteral nutrition suspected to be deficient: 200-250 μg/day for 2 weeks parenterally, then reassess insulin resistance 1
Monitoring Considerations
- Regular monitoring of chromium status is not routinely recommended 1
- Testing should be performed only when there is clinical suspicion of deficiency or toxicity 1
- Serum chromium can be determined but is rarely required 1
- C-reactive protein should be determined at the same time as any micronutrient analysis 1
Key Pitfalls to Avoid
- Confusing the different forms of chromium: Cr(III) is essential while Cr(VI) is toxic
- Unnecessary supplementation: Chromium supplementation has not shown consistent benefits for type 2 diabetes management 1
- Overlooking potential contamination in parenteral nutrition: Chromium contaminants in PN solutions can increase the amount delivered by 10-100% 1
- Failing to adjust doses in renal impairment: Chromium is excreted in urine, so dose reduction should occur in renal failure 1