Micronutrients and food choice: A case of 'nutritional wisdom' in humans?

Further evidence for sensitivity to energy density and a two-component model of meal size: Analysis of meal calorie intakes in Argentina and Malaysia

Previously, we demonstrated a non-linear association between meal caloric intake and meal energy density (ED, kcal/g) in data from a controlled trial in the US and from free-living participants in the UK [1]. In both datasets, meal caloric intake increased with ED in lower energy-dense meals (below ∼1.75 kcal/g) and decreased in higher energy-dense meals (above ∼1.75 kcal/g). In the current study, we sought to explore whether this pattern extends to data from free-living participants in Argentina (N = 2738 meals) and Malaysia (N = 4658 meals). Again, a significant breakpoint was found in both the Argentinean (2.04 kcal/g (SE = 0.06)) and Malaysian (2.17 kcal/g (SE = 0.06)) datasets with mean centered meal caloric intake increasing with ED below the breakpoint and decreasing above the breakpoint. These results lend further support for our two-component theoretical model of meal size (g) in which a volume signal is dominant in lower energy-dense meals and a calorie-content signal is dominant in higher energy-dense meals. Together, our research adds to evidence supporting human sensitivity to calories and exposes a complexity in the correspondence between meal energy content and meal size in everyday (non-manipulated) meals. Further research is needed to provide causal evidence for this sensitivity and whether individual variation impacts meal size and energy balance.

The Iron and Calcium Availability and the Satiating Effect of Different Biscuits

Biscuits are bakery products made with wheat flour. Wheat is a good source of minerals and dietary fibre, although the presence of phytate or other components could modify mineral availability. In addition, cereal-based products are usually characterised by high fibre content that can influence satiety. The objectives of this study were to evaluate both the iron and calcium availability and the satiety effect of different types of biscuits (traditional recipe vs. "Digestive") sold in the Spanish market, identifying whether the biscuit type could have effects on these parameters. Nutritional composition and the use of the generic descriptor "Digestive" of biscuits were collected from labels. Phytate and mineral contents were also measured. All samples were previously digested by a simulated process of the gastrointestinal conditions. The satiating effect of biscuits was evaluated according to VAS questionnaires. Results indicated that the mineral content and availability were different between types of biscuits (the traditional recipe showed the highest calcium concentration, while iron was higher in the "Digestive" type). However, mineral availability showed the highest percentages for both minerals, calcium and iron, in the Maria-type samples. Regardless of the different fibre content of both types of biscuits, and despite being higher in the Digestive type than in the Maria type, the satiety measures indicated that the Maria type had more effect on the food intake control. Thus, the descriptor "Digestive¨ in biscuits does not seem to be a marker of better nutritional quality, including parameters of effects on health such as mineral availability or satiety.

Human nutritional intelligence underestimated? Exposing sensitivities to food composition in everyday dietary decisions

The social and cultural significance of food is woven into every aspect of our dietary behaviour, and it contributes to our complex interaction with food. To find order within this complexity scientists often look for dietary 'universals' - phenomena or basic principles that guide our food choice and meal size, irrespective of wider context. One such idea is that taste characteristics provide a signal for dietary composition (e.g., sweet taste signals carbohydrate). Others have suggested that behaviour is guided by learning and is based on associations that form between the flavour of a food and its post-ingestive effects. Despite a large body of research, evidence supporting both processes is equivocal, leading some to conclude that humans are largely indifferent to food composition. Here, we argue that human abilities to gauge the nutritional composition or value of food have been underestimated, and that they can be exposed by embracing alternative methods, including cross-cultural comparisons, large nutrition surveys, and the use of virtual portion-selection tools. Our group has focused on assessments of food choice and expected satiety, and how comparisons across everyday foods can reveal non-linear relationships with food energy density, and even the potential for sensitivity to micronutrient composition. We suggest that these abilities might reflect a complex form of social learning, in which flavour-nutrient associations are not only formed but communicated and amplified across individuals in the form of a cuisine. Thus, rather than disregarding sociocultural influences as extraneous, we might reimagine their role as central to a process that creates and imbues a 'collective dietary wisdom.' In turn, this raises questions about whether rapid dietary, technological, and cultural change disrupts a fundamental process, such that it no longer guarantees a 'nutritional intelligence' that confers benefits for health.

Testing the protein-leverage hypothesis using population surveillance data

It is hypothesized that humans exhibit 'protein leverage' (PL), whereby regulation of absolute protein intake results in the over-consumption of non-protein food on low percentage protein diets. Testing for PL using dietary surveillance data involves seeking evidence for a negative association between total energy intake and percentage energy from protein. However, it is unclear whether such an association might emerge without PL due to the structure of intake data (protein and non-protein intakes have different means and variances and covary). We derive a set of models that describe the association between the expected estimate of PL and the distributions of protein and non-protein intake. Models were validated via simulation. Patterns consistent with PL will not emerge simply because protein intake has a lower mean and/or variance than non-protein. Rather, evidence of PL is observed where protein has a lower index of dispersion (variance/mean) than non-protein intake. Reciprocally, the stronger PL is the lower the index of dispersion for protein intake becomes. Disentangling causality is ultimately beyond the power of observational data alone. However, we show that one can correct for confounders (e.g. age) in generating signals of PL, and describe independent measures that can anchor inferences around the role of PL.

Vegans, vegetarians and omnivores differ in nutrient hedonics, salt and sweet preference and flavouring

BACKGROUND

Dietary content can influence taste responses. Therefore, we compared nutrient hedonics (liking foods by nutrient content), and seasoning, including taste responses to the prime flavours salt and sweet in 30 vegan, 37 vegetarian and 56 omnivore men and women.

METHODOLOGY

Questionnaires and taste tests examined macronutrient and electrolyte intake and hedonics, seasoning, salt and sweet preferences and psychophysical taste responses.

RESULTS

Compared to omnivores, vegans had lower protein, Ca⁺⁺, Na⁺ intake, and increased carbohydrate (CHO) intake. Independently of intake, hedonics for protein Ca⁺⁺ and Na⁺ were reduced and increased for CHO. Psychophysical responses to NaCl and sucrose also differed slightly, vegans and vegetarians scoring high concentrations of sucrose as more intense, Vegans reported more sweetening and less salting of food, added more sucrose to a test tea, less salt to a test soup, but did not differ in seasoning with oil or hot spice.

PRINCIPAL CONCLUSIONS

Habitual vegan, vegetarian and omnivore diets may alter taste responses to nutrient content and salt and sweet, the latter more pronounced in vegan and vegetarian women. Recognising diet-dependent changes in taste hedonics can inform diets and products.