Reported Chromium Concentrations In Foods

Dietary chromium intakes reported before 1977 are at least three times higher than those reported more recently. Valid data on the chromium content of foods are very limited. This is primarily because of the difficulty in collecting and analyzing chromium accurately in food samples [6, 7, 18]. In earlier analyses, much of the reported chromium was acquired through contamination in sampling, sample homogenization, and analysis.

Little is known about variation in chromium concentration in plants grown in different areas of North America. Cary and Kubota analyzed samples collected from sites in Maryland, North Carolina, and northern California. Plant samples taken from areas with high-chromium soils contained higher concentrations of chromium than plants grown on low-chromium soils. Nonetheless, the authors noted that some of this chromium was apparently due to contamination of the plant material by soil chromium [19], and samples were ground in a Wiley mill fitted with a stainless steel screen which would also create the potential of sample contamination with chromium.

Most staple foods apparently provide less than 10g/kg chromium [7]. However, a number of developing countries have reported higher dietary intakes than those reported by trace element laboratories in Scandinavian countries and in the US raising questions of regional differences or contamination problems.

With the exception of sugar which is often very low in chromium, processed foods generally are higher in chromium content than fresh foods [7]. Offenbacher and Pi-Sunyer reported on release of chromium from stainless steel into water and fruit juices [20]. The ability of water to stimulate chromium release from stainless steel was primarily dependent on pH. All processed fruit juices contained higher amounts of chromium than hand-squeezed juices, but the amount of chromium taken up in the acid juices did not parallel their pH. More chromium was taken up by juices than by the acidified water perhaps due to the characteristic organic acids in the juices. Amounts of chromium released into juices were 3-5 ^g/100mL which could make important contributions to overall chromium intake [20].

Anderson and coworkers analyzed chromium in breakfast cereals and found concentrations ranging from 3 to 701ng/g. These cereals would then provide 0.2530.7 |g Cr/serving. Many provided more than 5 |gCr/serving and ready-to-eat bran cereals tended to be higher than others [21]. Variation seemed to be due to contamination from processing and/or fortification. Contaminating chromium may help to meet human chromium requirement.

A number of individual food items with chromium concentrations were reported by the Beltsville Human Nutrition Research Center group [22]. Dairy products were poor sources of chromium. Milk at <0.12 |gCr/serving added little to the daily chromium intake. Meats, poultry, and fish, except for one processed luncheon meat analyzed, were generally low in chromium with one serving providing 0.5-3.6 |g chromium. The turkey ham, on the other hand, had 10.4 |g chromium in a 3-ounce serving. Because unprocessed turkey had <2 |g Cr/serving, it would seem that much of the chromium in turkey ham came from the processing [22].

Chromium content of fruits and vegetables varied from 0.1 to 22 |g/serving. A serving of broccoli at 22 |g/serving provided more than three-fold more Cr than any other vegetable or fruit tested. The authors indicated follow-up tests were being done, but no additional papers have been published in this area [22]. Perhaps the broccoli retained traces of soil; earlier studies had noted the difficulty in avoiding contamination of some plant samples with soil [19].

The brand of barbeque sauce tested contained 1.73 |g Cr/tablespoon. Some spices have high chromium concentrations, but because the usual diet contains only a very small amount of these substances, they do not make a major contribution to the overall daily chromium intake [22].

Chromium concentrations in beer were found to vary widely, from 0.48 to 56 ng/mL. Chromium in 8 brands of beer was below 2 ng/mL, 11 beers ranged from 2 to 10 ng/mL, and 8 brands of beer had chromium concentrations above 10 ng/mL. Chromium concentration in the brewing water was 0.5 ng/mL or less. Based on the relative amounts of the components present in beer, the authors estimated the following contributions per liter to the overall chromium content: water, 0.5 |g; corn grits, 0.3 |g; malt, 4.8 |g; and hops 1.2 |g for a total of ~6.8 |g/L of beer. Additional chromium came from unknown sources, but some release from stainless steel may have been a possibility [22].

Wine is also a potential source of small amounts of chromium. Although mean concentrations were similar for red and white wines tested in France, the red wine ranged from 7 to 90 |g Cr/L and the white wine ranged from 7 to 44 |g Cr/L. The chromium concentrations of 94% of all wines tested were <40 |g/L. The authors estimated the contribution of wine consumption to total Cr dietary intake for the French population to be ~4 |xg/day [23].

Different lots of food were found to have different chromium concentrations [2, 7, 21, 22], and Anderson and colleagues concluded that "much chromium in foods may originate from external sources during growing, processing, preparation, fortification, and handling." Only a relatively small number of foods have been analyzed for chromium; the variability between different lots and different preparation techniques means that database values for chromium, even if they exist, are unlikely to provide an accurate assessment of a person's actual chromium intake.

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