Influence of Meal Sequence and Number of Teeth Present on Nutrient Intake Status: A Cross-Sectional Study

Intake of fiber, as well as protein, and lipid preloading help to control postprandial glycemic elevation in people with type 2 diabetes and in healthy individuals. However, there are few studies on the awareness of meal sequence and nutrient intake status that consider oral conditions. This cross-sectional study aimed to determine the effects of meal sequences on nutrient intake status and whether these relationships were related to the number of teeth present. The subjects were recruited from the Medical and Dental Collaboration Center of Kanagawa Dental University Hospital between 2018 and 2021. Medical and dental examinations were performed, and a questionnaire was used to determine whether the diet consisted of vegetables, meat or fish, and carbohydrates in that order. Nutrient intake status was assessed using the brief-type self-administered diet history questionnaire. Data were collected from 238 participants. The group with awareness of meal sequence ingested increased nutrients such as n-3 fatty acids, total dietary fiber, calcium, and vitamin C. Saturated fatty acid intake increased in those with fewer teeth, while it was not significantly related to meal sequence. In conclusion, our results showed that meal sequence was associated with nutrient intake status. In addition, the intake of saturated fatty acids increased when many teeth were lost, regardless of meal sequence.

Regulation of Postabsorptive and Postprandial Glucose Metabolism by Insulin-Dependent and Insulin-Independent Mechanisms: An Integrative Approach

Glucose levels in blood must be constantly maintained within a tight physiological range to sustain anabolism. Insulin regulates glucose homeostasis via its effects on glucose production from the liver and kidneys and glucose disposal in peripheral tissues (mainly skeletal muscle). Blood levels of glucose are regulated simultaneously by insulin-mediated rates of glucose production from the liver (and kidneys) and removal from muscle; adipose tissue is a key partner in this scenario, providing nonesterified fatty acids (NEFA) as an alternative fuel for skeletal muscle and liver when blood glucose levels are depleted. During sleep at night, the gradual development of insulin resistance, due to growth hormone and cortisol surges, ensures that blood glucose levels will be maintained within normal levels by: (a) switching from glucose to NEFA oxidation in muscle; (b) modulating glucose production from the liver/kidneys. After meals, several mechanisms (sequence/composition of meals, gastric emptying/intestinal glucose absorption, gastrointestinal hormones, hyperglycemia mass action effects, insulin/glucagon secretion/action, de novo lipogenesis and glucose disposal) operate in concert for optimal regulation of postprandial glucose fluctuations. The contribution of the liver in postprandial glucose homeostasis is critical. The liver is preferentially used to dispose over 50% of the ingested glucose and restrict the acute increases of glucose and insulin in the bloodstream after meals, thus protecting the circulation and tissues from the adverse effects of marked hyperglycemia and hyperinsulinemia.

A Review of Recent Findings on Meal Sequence: An Attractive Dietary Approach to Prevention and Management of Type 2 Diabetes

While adjustment of total energy and nutritional balance is critically important, meal sequence, a relatively simple method of correcting postprandial hyperglycemia, is becoming established as a practical dietary approach for prevention and management of diabetes and obesity. Meal sequence, i.e., consumption of protein and/or fat before carbohydrate, promotes secretion of glucagon-like peptide-1 (GLP-1) from the gut and ameliorates secretions of insulin and glucagon and delays gastric emptying, thereby improving postprandial glucose excursion. GLP-1 is known to suppress appetite by acting on the hypothalamus via the afferent vagus nerve. Thus, enhancement of GLP-1 secretion by meal sequence is expected to reduce body weight. Importantly, consumption of a diet rich in saturated fatty acids such as meat dishes before carbohydrate increases secretions of not only GLP-1 but also glucose-dependent insulinotropic polypeptide (GIP), which promotes energy storage in adipose tissue and may lead to weight gain in the long term. Dietary fiber intake before carbohydrate intake significantly reduces postprandial glucose elevation and may have a weight loss effect, but this dietary strategy does not enhance the secretion of GLP-1. Thus, it is suggested that their combination may have additive effects on postprandial glucose excursion and body weight. Indeed, results of some clinical research supports the idea that ingesting dietary fiber together with meal sequence of protein and/or fat before carbohydrate benefits metabolic conditions of individuals with diabetes and obesity.

The Metabolic Concept of Meal Sequence vs. Satiety: Glycemic and Oxidative Responses with Reference to Inflammation Risk, Protective Principles and Mediterranean Diet

With increasing exposure to eating opportunities and postprandial conditions becoming dominant states, acute effects of meals are garnering interest. In this narrative review, meal components, combinations and course sequence were questioned vis-à-vis resultant postprandial responses, including satiety, glycemic, oxidative and inflammatory risks/outcomes vs. protective principles, with reference to the Mediterranean diet. Representative scientific literature was reviewed and explained, and corresponding recommendations discussed and illustrated. Starting meals with foods, courses and/or preloads high in innate/added/incorporated water and/or fibre, followed by protein-based courses, delaying carbohydrates and fatty foods and minimizing highly-processed/sweetened hedonic foods, would increase satiety-per-calorie vs. obesogenic passive overconsumption. Similarly, starting with high-water/fibre dishes, followed by high-protein foods, oils/fats, and delayed/reduced slowly-digested whole/complex carbohydrate sources, optionally closing with simpler carbohydrates/sugars, would reduce glycaemic response. Likewise, starting with foods high in innate/added/incorporated water/fibre/antioxidants, high monounsaturated fatty acid foods/oils, light proteins and whole/complex carbohydrate foods, with foods/oils low in n-6 polyunsaturated fatty acids (PUFA) and n-6:n-3 PUFA ratios, and minimal-to-no red meat and highly/ultra-processed foods/lipids, would reduce oxidative/inflammatory response. Pyramids illustrating representative meal sequences, from most-to-least protective foods, visually communicate similarities between axes, suggesting potential unification for optimal meal sequence, consistent with anti-inflammatory nutrition and Mediterranean diet/meal principles, warranting application and outcome evaluation.