Nutritional epidemiology at a crossroad: how to link observations with interventions and why?

Nutrients and amyloid β status in the brain: A narrative review

Amyloid beta (Aβ) is a peptide and a hallmark of Alzheimer's disease (AD). Emerging evidence suggests that Aβ levels could be influenced by diet. However, the evidence is sparse and for some nutrients, controversial. The aim of this narrative review is to gather the findings of observational and clinical trials involving human participants on the relationships between nutrients and brain Aβ status. Some dietary patterns are associated to reduced levels of Aβ in the brain, such as the Mediterranean diet, ketogenic diet as well as low intake of saturated fat, high-glycemic-index food, sodium, and junk/fast food. Low Aβ status in the brain was also associated with higher density lipoproteins (HDL) cholesterol and polyunsaturated fatty acids consumption. Data on alcohol intake is not conclusive. On the contrary, high Aβ levels in the brain were related to a higher intake of total cholesterol, triglycerides, low-density lipoproteins (LDL) cholesterol, saturated fat, sucrose, and fructose. Folic acid, cobalamin, vitamin E, and vitamin D were not associated to Aβ status, while high blood concentrations of Calcium, Aluminum, Zinc, Copper, and Manganese were associated with decreased Aβ blood levels but were not associated with Aβ cerebral spinal fluid (CSF) concentrations. In conclusion, certain dietary patterns and nutrients are associated to brain Aβ status. Further research on the association between nutrients and brain Aβ status is needed in order to pave the way to use nutritional interventions as efficacious strategies to prevent Aβ disturbance and potentially AD.

Substitutions of Oatmeal and Breakfast Food Alternatives and the Rate of Stroke

Background and Purpose- Studies indicate that consuming breakfast every day, and particularly oatmeal, is associated with lower risk of stroke. However, few studies have considered replacement foods when considering foods usually consumed at breakfast. We, therefore, aimed to model substitutions between the breakfast food products oatmeal, eggs, yogurt, or white bread and subsequent risk of stroke. Methods- Participants from the Danish cohort study (Diet, Cancer and Health; n=55 095) were followed for 13.4 years, during which 2260 subjects experienced a first-ever stroke. Breakfast foods were assessed using a validated 192-item food-frequency questionnaire at baseline. Cox proportional hazards models were used to estimate adjusted hazard ratios and 95% CIs for associations between hypothetical substitutions of standard portion sizes of breakfast foods and stroke. Results- Modeling replacement of white bread or eggs with oatmeal was associated with a lower rate of total stroke (hazard ratio [HR]=0.96 [95% CI, 0.95-0.98]; HR=0.96 [95% CI, 0.93-0.98], respectively), total ischemic stroke (HR=0.96 [95% CI, 0.94-0.98]; HR=0.96 [95% CI, 0.94-0.99], respectively), and ischemic stroke due to small-artery occlusion (HR=0.95 [95% CI, 0.93-0.98]; HR=0.95 [95% CI, 0.91-0.99], respectively). Furthermore, modeling replacement of eggs with oatmeal was associated with a lower rate of total hemorrhagic stroke (HR=0.94 [95% CI, 0.89-0.99]). Modeling replacement of yogurt with oatmeal was not associated with stroke. Conclusions- Our findings suggest that a diet containing oatmeal instead of white bread or eggs may be associated with a lower rate of stroke.