Consumption of ultra-processed foods and cancer risk: results from NutriNet-Santé prospective cohort.
BMJ (Clinical research ed.). 2018;360:k322
Plain language summary
Foods that are heavily processed tend to have high levels of total fat, sugar and salt and low levels of fibre and vitamins. They also tend to have high levels of contaminants (caused for example by high heat treatment), food additives and plastic packaging exposure. This large prospective population-based cohort study assessed the association between ultra-processed food consumption and the incidence of cancer. The study found that ultra-processed food intake was associated with a higher overall cancer risk and a higher breast cancer risk. A 10% increase in the consumption of ultra-processed foods was associated with an increase of more than 10% greater risk of overall and breast cancer risk. The authors call for further studies to better understand the different elements of food processing and their association to cancer risk.
OBJECTIVE To assess the prospective associations between consumption of ultra-processed food and risk of cancer. DESIGN Population based cohort study. SETTING AND PARTICIPANTS 104 980 participants aged at least 18 years (median age 42.8 years) from the French NutriNet-Santé cohort (2009-17). Dietary intakes were collected using repeated 24 hour dietary records, designed to register participants' usual consumption for 3300 different food items. These were categorised according to their degree of processing by the NOVA classification. MAIN OUTCOME MEASURES Associations between ultra-processed food intake and risk of overall, breast, prostate, and colorectal cancer assessed by multivariable Cox proportional hazard models adjusted for known risk factors. RESULTS Ultra-processed food intake was associated with higher overall cancer risk (n=2228 cases; hazard ratio for a 10% increment in the proportion of ultra-processed food in the diet 1.12 (95% confidence interval 1.06 to 1.18); P for trend<0.001) and breast cancer risk (n=739 cases; hazard ratio 1.11 (1.02 to 1.22); P for trend=0.02). These results remained statistically significant after adjustment for several markers of the nutritional quality of the diet (lipid, sodium, and carbohydrate intakes and/or a Western pattern derived by principal component analysis). CONCLUSIONS In this large prospective study, a 10% increase in the proportion of ultra-processed foods in the diet was associated with a significant increase of greater than 10% in risks of overall and breast cancer. Further studies are needed to better understand the relative effect of the various dimensions of processing (nutritional composition, food additives, contact materials, and neoformed contaminants) in these associations. STUDY REGISTRATION Clinicaltrials.gov NCT03335644.
Self-reported bovine milk intake is associated with oral microbiota composition.
PloS one. 2018;13(3):e0193504
Plain language summary
Dietary bovine milk consumption has been associated with both positive and negative health effects. The aim of this study was to explore the association between bovine milk intake and oral microbiota profile. Saliva and tooth biofilm samples were obtained from 154 Swedish adolescents and food frequency questionnaires were completed. A replication cohort of 31,571 was also studied to find patterns in diet intake, lifestyle factors and dental caries. The primary finding of this study was that bovine milk consumption can modulate oral microbiota, and that low milk intake was associated with higher prevalence of opportunistic bacteria. Interestingly there was no association between milk intake and dental caries, highlighting the complexity of this disease. Based on these results, the authors hypothesise milk consumption may also produce similar effects in the gut microbiome.
Bovine milk intake has been associated with various disease outcomes, with modulation of the gastro-intestinal microbiome being suggested as one potential mechanism. The aim of the present study was to explore the oral microbiota in relation to variation in self-reported milk intake. Saliva and tooth biofilm microbiota was characterized by 16S rDNA sequencing, PCR and cultivation in 154 Swedish adolescents, and information on diet and other lifestyle markers were obtained from a questionnaire, and dental caries from clinical examination. A replication cohort of 31,571 adults with similar information on diet intake, other lifestyle markers and caries was also studied. Multivariate partial least squares (PLS) modelling separated adolescents with low milk intake (lowest tertile with <0.4 servings/day) apart from those with high intake of milk (≥3.7 servings/day) based on saliva and tooth biofilm, respectively. Taxa in several genera contributed to this separation, and milk intake was inversely associated with the caries causing Streptococcus mutans in saliva and tooth biofilm samples by sequencing, PCR and cultivation. Despite the difference in S. mutans colonization, caries prevalence did not differ between milk consumption groups in the adolescents or the adults in the replication cohort, which may reflect that a significant positive association between intake of milk and sweet products was present in both the study and replication group. It was concluded that high milk intake correlates with different oral microbiota and it is hypothesized that milk may confer similar effects in the gut. The study also illustrated that reduction of one single disease associated bacterial species, such as S. mutans by milk intake, may modulate but not prevent development of complex diseases, such as caries, due to adverse effects from other causal factors, such as sugar intake in the present study.