Selenium in humans: which is the safe range of intake?

Marco Vinceti, Tommaso Filippini, Federica Violi, Marcella Malavolti, Carlotta Malagoli, Annalisa Bargellini, Paola Borella

Oral presentation at "Trace elements between deficiency and toxicity: update and perspectives". Modena - October 1-2, 2015

The role of selenium in human health and disease has been object of extreme interest in the latest years, as shown by the large and still quickly growing number of studies which investigated the biological properties and health effects of this essential trace element. Laboratory and epidemiologic studies support a broad and sometimes very conflicting pattern of effects, making it difficult to reconcile such evidence in single unifying view. In fact, among other properties selenium has been suggested to both protect against cancer and to induce it, to protect against diabetes and to exert diabetogenic effects, to be neurotoxic and neuroprotective, and under a toxicological perspective to be both pro-oxidant and anti-oxidant, genotoxic and anti-genotoxic. Adding further complexity to this issue, a few randomized trials have been carried out using organic selenium in US populations, yielding results considerably changing over time and showing concerning findings in the most recent studies.

In addition, throughout the latest decades there have been considerably uncertainty and debate about the best criteria to assess adequacy of selenium exposure, in order to avoid both deficiency and overexposure. Under this perspective, both proteomic markers and epidemiological considerations have been proposed to identify a safe range of intake of the metalloid, but the evaluations of regulatory agencies as well as of investigators greatly differ about which indicators are to be chosen and to what extent may be reliable.

A final issue which must be considered when assessing the human health effects of selenium are the specific selenium compounds under consideration, its speciation. The various chemical forms of this element have shown markedly different effects in laboratory and veterinary studies, and this may considerably influence its health effects in the human. The selenium species found in drinking water and in the occupational environment, for example, are exclusively or mainly inorganic, while selenium compounds in foods mainly tend to be organic, thus showing markedly different metabolism and pronounced differences in nutritional and toxic properties. In this presentation, the epidemiologic evidence underlying the issue of selenium safe range of intake, as well as the potential nutritional and toxicological endpoints to be considered in such risk assessment, will be summarized, critically analyzed and discussed.

Dietary cadmium intake and breast cancer risk: a meta-analysis of longitudinal studies and results of the ORDET cohort study

Marco Vinceti, Sabina Sieri, Tommaso Filippini, Vittorio Krogh

Oral presentation at II° Cadmium Symposium 2015. Sassari - June 25-27, 2015

Cadmium is a heavy metal with estrogenic activity and established human carcinogenicity, but uncertainties exist about the amounts of exposure and the cancer types involved. In particular, the possibility that dietary cadmium may increase breast cancer risk was suggested by one cohort study, but results of the other four longitudinal investigations were inconsistent. We meta-analyzed these studies using a random-effects model, and we computed the summary relative risk (RR) of breast cancer along with its 95% confidence interval (CI) in subjects with the highest versus the lowest cadmium intake category. Summary RR was 1.00 (95% CI 0.87-1.15), while limiting the analysis to estrogen-receptor positive breast cancer RR was 1.05 (0.94-1.16). We also investigated the relation between cadmium intake and breast cancer risk in the ORDET cohort, a prospective study of 9,343 healthy women of Varese province, Northern Italy, recruited between 1987 and 1992 and followed for cancer occurrence until December 2009. Dietary habits and the corresponding estimated cadmium intake were assessed at baseline via a food frequency questionnaire. During 158,190 person-years of follow-up, 419 breast cancer cases occurred. In a multivariate Cox regression model adjusting for several potential confounders, the hazard ratio (HR) of breast cancer increased with increasing quintiles of cadmium intake, with values of 1.19, 1.23, 1.36 and 1.66, respectively (P trend=0.019) compared with bottom category. HR associated with 1-unit increase of Cd intake was 1.12 (1.03-1.21). After stratifying the analysis according to estrogen-receptor, human epidermal growth factor-receptor 2 and progesterone-receptor status, the receptor-positive breast cancer subtypes showed the strongest association with cadmium intake. Overall, these results suggest that dietary cadmium increases breast cancer risk, particularly for some disease subtypes, though the possibility of unmeasured confounding must also be considered.


Fattori predittivi per la cessazione dal fumo nel centro per il trattamento del tabagismo della provincia di Reggio Emilia: analisi di due anni di attività

S.Storani, M.Tamelli, C.Malagoli, T.Filippini, M.Vinceti

Presentazione orale al 47° Congresso Nazionale SItI del 1-4 Ottobre 2014, Riccione


Gli interventi di cessazione dal fumo di sigaretta costituiscono una delle azioni cardine per il contrasto al tabagismo e sono propri del livello specialistico per la diagnosi e il trattamento della dipendenza tabagica che in Italia è svolto dai Centri Anti Fumo (CAF). I modelli terapeutici dei CAF possono essere ricondotti ai principi del counselling individuale, della terapia cognitivo-comportamentale di gruppo e della farmacoterapia. I tassi di cessazione a 6 mesi nei CAF italiani variano dal 28 al 36,6% (Belleudi V, Gorini G) e il trattamento in un CAF può determinare un aumento fino a quattro volte della probabilità di rimanere astinenti a 1 anno rispetto alla probabilità del 3-8% dei fumatori smettono da soli (Fiore MC, Anthonisen NR). Il CAF provinciale di Reggio Emilia (CAF-Re) dal 2011 è attivo in ogni Distretto e cogestito dalla Lega Italiana Contro i Tumori e dall'Azienda Ausl. Obiettivi del presente lavoro sono determinare i tassi di cessazione a 6 e 12 mesi dei fumatori afferenti al CAF Re e individuare eventuali caratteristiche cliniche o del trattamento predittive di successo.