Cadmium bioavailability from edible sunflower kernels: a long-term study with men and women volunteers

The contribution of cacao consumption to the bioaccessible dietary cadmium exposure in the Belgian population

Since 2019, EU limits apply to cadmium (Cd) concentrations in cacao-derived food products. The dietary risk assessment leading to that regulation used consumption surveys aggregated to a limited number of chocolate product categories and did not consider differences in Cd bioaccessibility. Here, the cacao-related dietary Cd exposure in the Belgian population was estimated with higher resolution and accounting for bioaccessibility. A food frequency questionnaire and a 24-h recall (N = 2055) were set up for the Belgian population, in combination with ICP-MS analysis of a large subset of cacao-containing products (N = 349). Both the average chocolate consumption (28 g day^-1) and the relative contribution of chocolate to the total dietary Cd exposure (7-9%) were higher than previously estimated for the Belgian population, probably because of some selection bias towards chocolate consumers in the cohort. The Cd bioaccessibility in chocolate products was a factor 5 (cacao powder) and 2 (dark chocolate) lower compared to wheat flour, suggesting lower bioavailability in chocolate than in wheat, which is a main contributor to dietary Cd. This study suggests that Cd intake from cacao consumption has been underestimated because of hidden cacao in non-chocolate food categories but, in contrast, may have overestimated the true exposure because of lower bioavailability compared to the main foodstuffs contributing to Cd exposure.

Antioxidant power as biochemical endpoint in bread for screening and early managing quality and toxicant-related safety anomalies in food production

Flaxseeds are both a food ingredient and a natural source of antioxidants (e.g. lignans, PUFAs) and pro-oxidant contaminants (e.g. cadmium): the variable mixture of anti- and pro-oxidant substances may impact on the redox homeostasis of flaxseed-enriched foods. The antioxidant power is studied here as biochemical activity of flaxseeds in white wheat bread and as endpoint for possible screening of anomalous variations of bioactive mixtures (antioxidants vs. prooxidants) in food matrices. A bioprobe assay based on the superoxide dismutase (SOD) enzyme (6 channels of the multiprobe bioelectronic platform BEST) was performed on white wheat bread with and without flaxseeds. Nine BEST channels were simultaneously used for validation and monitoring of measuring conditions (temperature, pH, conductivity). Findings were compared with quantitative analysis of antioxidants and pro-oxidant contaminants. Organic and aqueous extracts of both bread types were examined in parallel. The SOD-probe detected the difference in antioxidant power given by 10% flaxseed, thus supporting the use of antioxidant power detected by bioenzymatic screening as sensitive biochemical endpoint. Mixtures of bioactive molecules in foods generate biochemical activities that can be monitored as time-effective indicators of invariability, which is pivotal in the daily control of anomalies in food production and therefore in the protection of consumers' health.

Dietary dried egg white protein influences accumulation and distribution of cadmium in rats

The effect of a dried egg white dietary supplement (2%) on cadmium distribution was examined within 32 d post dosing in the carcass, liver, kidneys, testes, and thigh muscles of male Wistar rats administered cadmium chloride daily, orally for 28 d at a dose corresponding to 10 mg/Cd/kg of feed. Rats fed the egg white protein-supplemented diet displayed markedly higher carcass Cd retention than animals given a standard diet. Further, the protein-supplemented diet increased significantly hepatic Cd retention at 12 h and 4 d, and renal metal retention at 12 h until d 16. In contrast, testicular and thigh-muscle Cd retention was significantly lower in the rats fed the egg white protein supplemented diet compared to rats on a standard diet. Higher carcass, hepatic, and renal Cd concentrations were accompanied by greater body weight gains. Taken together, the results of this study showed that increased egg white dietary protein levels enhanced Cd retention in carcass, liver, and kidneys but lowered the metal concentrations in thigh muscles and testes. Data indicate that body weight gains in rats supplemented with egg white proteins exerted tissue-specific effects with respect to Cd accumulation. The potential toxic risk of Cd burden in testes was diminished due to lower metal levels in rats on a protein-supplemented diet. However, this may not be the case in liver and kidneys, as Cd concentrations rose in presence of protein supplementation.

Cadmium absorption and retention by rats fed durum wheat (Triticum turgidum L. var. durum) grain

A whole-body radioassay procedure was used to assess the retention and apparent absorption by rats of Cd in kernels of durum wheat (Triticum turgidum L. var. durum) harvested from plants grown hydroponically in 109Cd-labelled nutrient solution. Wholegrain wheat, containing 5 micromol Cd (570 microg)/kg dry weight labelled intrinsically with 109Cd, was incorporated into test meals fed to rats that had been maintained on diets containing marginally adequate, adequate or surplus levels of Zn (0.12 mmol (8 mg), 0.43 mmol (28 mg) or 1.55 mmol (101 mg) Zn/kg respectively), and either 0 or 50 g durum wheat/kg. Regardless of diet, all rats consumed about 99 % of the test meal offered. In rats fed diets without wheat, initial Cd absorption averaged 7.7, 4.6 and 2.4 % of the dose when the diet contained 0.12 mmol (8 mg), 0.43 mmol (28 mg) or 1.55 mmol (101 mg) Zn/kg diet respectively. In rats fed wheat-containing diets, initial Cd absorption averaged 3.8 and 2.6 % of the dose when dietary Zn concentration was 0.12 mmol (8 mg) and 0.43 mmol (28 mg)/kg diet respectively. The amount of Cd retained in the body at 15 d postprandial was <2 % of the dose in all rats, and decreased as Zn in the diet increased. Even at 15 d postprandial, 32 to 44 % of the Cd retained in the body was still in the gastrointestinal tract. The results show that: (1) the bioavailability to rats of Cd in wholegrain durum wheat was depressed when wholegrain wheat was part of the regular diet; (2) increased intake of dietary Zn lowered Cd absorption and retention; (3) retention of Cd in the body at 15 d postprandial from diets containing adequate Zn was <1.3 %.

Cadmium absorption in women fed processed edible sunflower kernels labeled with a stable isotope of cadmium, (113)Cd

The apparent fractional absorption of cadmium (Cd) from sunflower kernels (SFK) was determined in women volunteers by using kernels labeled with a stable isotope of Cd ((113)Cd) by injecting it into the flowering head. Fourteen women who were between the ages of 30 and 70 years, who did not use tobacco products, who were in good health, and who had been consuming a self-selected diet low in Cd content participated in the study. The volunteers were fed a breakfast composed primarily of cereal, milk, and fruit juice. The breakfast also contained a portion of (113)Cd-labeled SFK processed into a buttery spread. Each volunteer collected individual stool samples for 21 days beginning immediately after they had consumed the labeled kernels. The total amounts of Cd and (113)Cd excreted in each stool were determined by isotope dilution inductively coupled plasma mass spectrometry. Mean fecal Cd excretion was 14.1+/-4.1 microg/day and mean (113)Cd absorption was 10.6+/-4.4%. In agreement with previous studies, no significant (P>0.3) correlation between Cd absorption and serum ferritin concentrations was found in women whose serum ferritin concentrations were >25 ng/mL. These data suggest that the availability of Cd from highly processed sunflower kernels to humans is similar to that reported for other types of food.