Letter to the editor

Chromium(III) and the glucose tolerance factor

This chapter presents a universal foundation material for scientists interested in the novel science of “nano” in bioapplications, particularly animal applications. The potential of nanoparticles, their activity, and significance in animal applications are briefly described. Nanomaterials have been found useful for several novel applications in the livestock industry. The use of nanominerals for enhancing the bioavailability of the mineral feed supplements is getting quite popular in the livestock industry. The synthesis and development of nanominerals employed in animal nutrition are also discussed. The material characterization of these nanoparticles performed by scanning electron microscope, transmission electron microscope X-ray diffraction patterns, and other diagnostic tools like magnetic resonance imaging to track the path of nanominerals is also highlighted in the chapter. Nanotechnology also has prospective applications in nutrition and drug delivery because materials at the nanoscale exhibit unique properties that are different from those of the isolated material or the bulk material. Minerals exert a vital role in the livestock nutrition. The potential of the nanominerals is highlighted especially for animal nutrition. The role of various nanominerals like calcium, zinc, and selenium, in animal nutrition, is described in detail. This chapter also addresses some of the concerns related to the toxicity associated with the nanoparticles while employing them in animal applications.

An experiment was conducted to investigate the effect of dietary chromium (Cr) supplementation on nutrient utilization and growth performance in Black Bengal goats. Thirty Black Bengal kids of 3–5 months (5.40 ± 0.34 kg body weight) were assigned randomly to five groups. The experimental diets consisted of a basal diet supplemented with Cr at the rate of 0 (basal diet without any supplementation), 1.0 and 1.5 mg/kg (inorganic Cr), and 1.0 and 1.5 mg/kg (organic Cr). The duration of the growth experiment was 150 d, followed by a 7-d digestibility trial. Results showed that the total dry matter and crude protein intake of Cr supplemented groups were comparable with the control group (P = 1.00). However, the nutrient utilization in the 1.5 mg/kg inorganic Cr and 1.5 mg/kg organic Cr groups were better, with a higher digestibility coefficient for dry matter, crude protein, ether extract, organic matter, total carbohydrate, and hemicellulose (P < 0.05) when compared with the remaining groups. The average daily gain of 1.5 mg/kg organic Cr supplemented groups were significantly higher than the rest of the groups (P = 0.039). Cr supplementation tended to improve the feed conversion ratio per dry matter intake (P = 0.09) and crude protein intake (P = 0.023) in all the treatment groups. In conclusion, dietary supplementation of 1.5 mg/kg organic Cr may positively influence the nutrient utilization and body weight gain of Black Bengal goats.

Among the many heavy metals, chromium (Cr) is one of the fascinating ones. In its two most prevalent oxidation forms, trivalent (Cr³⁺) and hexavalent (Cr⁶⁺), Cr has completely different toxicity and essentiality in human health, as well as in the soil. In humans, Cr³⁺ is a necessary micronutrient for metabolism of glucose, lipid, and proteins. In contrast, Cr⁶⁺ has no recognized biological functions and is a potent carcinogen. In the search for new and effective ways to protect humans from heavy metals, “gut remediation” using probiotics has been found to be a promising and sustainable approach. Here, we have reviewed the most recent literature on how Cr causes cellular toxicity and DNA damage via cellular oxidation and epigenetic modifications, along with current biological, chemical, and herbal remediation methods, with a focus on sustainable strategies such as gut remediation.

In this work, a principle of flow injection analysis (FIA) was applied for sample introduction to an electrospray ionization - ion trap mass spectrometer (ESI-ITMS) with the aim to quantify chromium(III) picolinate (CrPic₃) in commercial supplements by multiple reaction monitoring, and using cobalt(II) picolinate as internal standard (IS). FIA system was operated with ammonium formate 10 mmol L⁻¹ in methanol-water (1:1, v/v) as a carrier solution at a flow rate 200 μL min⁻¹; 100 μL injections were performed in 2-min intervals. Setting ion transitions m/z 419 → 270 and 304 → 260 for the analyte and IS, respectively, and 100 ms integration time, the method detection and quantification limits 12 ng g⁻¹ and 40 ng g⁻¹ of Cr (as CrPic₃) in the air-dried powder. Acetonitrile extracts of the real-world samples presented varying from sample-to-sample chemical composition and IS efficiently compensated for ionization interferences. Mean results from triplicate analysis of four different supplements were obtained with relative standard deviation 0.1–4.0%, indicating acceptable precision. Trueness of the proposed FIA-ESI-ITMS/MS procedure was demonstrated by 95.8–108% percentage recoveries attained in the analysis of the CrPic₃-spiked samples. For comparative purposes, total Cr was determined by ICP-MS. The quantitative results obtained indicate the necessity of analytical control of Cr(III) supplements commercially available and demonstrate that the proposed FIA-ESI-ITMS/MS procedure is well-suited for the determination of CrPic₃ in such products.

Chromium (Cr), one of the most abundant elements on earth, occurs in nature as chromite ore that is used for manufacturing various Cr compounds, Cr pigments, as well as Cr metal. Cr exists primarily in two oxidation states: trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)]. Most chromate compounds found naturally are trivalent while hexavalent Cr is usually a result of human dumping. Trivalent Cr appears to be a nutritional supplement for humans and animals and may play a role in the metabolism of glucose. In contrast, hexavalent Cr is 500–1000 times more toxic than Cr³⁺, and exposure to Cr(VI) results in a variety of tissue or cell damage. Thus, Cr compounds are of great significance to the health of workers in the industries related to chromate production, processing, and usage.

Occupational exposure to Cr occurs through three major routes: inhalation, oral ingestion, and direct dermal contact; while nonoccupational (environmental) exposure primarily comes from oral ingestion of Cr-rich foods and water or inhalation via cigarette smoking. The uptake of Cr through the airways and the digestive tract is much quicker in the hexavalent state than in the trivalent state. Cr is found in all human organs, in both adults and newborns. Cr is excreted via both urine and feces, but predominantly via the urine.

Long-term inhalation exposure to various Cr(VI) compounds has been shown to result in a high risk of carcinomas of the respiratory organs. When inhaled, some of the Cr(VI) compounds appear to be among the most potent human carcinogens. Numerous epidemiological studies have documented high incidences of respiratory cancers and increased risk of cancer-related death among workers chronically exposed to Cr(VI) via inhalation. The International Agency for Research on Cancer has classified Cr(VI) compounds as a Group I carcinogen to humans through inhalation. Compounds of Cr(VI) are shown to induce epigenetic changes, oxidative stress, chromosomal aberrations, and a variety of DNA damages leading to mutations, which eventually contribute to its toxicity and carcinogenicity.