Impact of overweight and glucose tolerance on postprandial responses to high- and low-glycaemic index meals

A New Approach to Personalized Nutrition: Postprandial Glycemic Response and its Relationship to Gut Microbiota

A prolonged and elevated postprandial glucose response (PPGR) is now considered a main factor contributing for the development of metabolic syndrome and type 2 diabetes, which could be prevented by dietary interventions. However, dietary recommendations to prevent alterations in PPGR have not always been successful. New evidence has supported that PPGR is not only dependent of dietary factors like the content of carbohydrates, or the glycemic index of the foods, but is also dependent on genetics, body composition, gut microbiota, among others. In recent years, continuous glucose monitoring has made it possible to establish predictions on the effect of different dietary foods on PPGRs through machine learning methods, which use algorithms that integrate genetic, biochemical, physiological and gut microbiota variables for identifying associations between them and clinical variables with aim of personalize dietary recommendations. This has allowed to improve the concept of personalized nutrition, since it is now possible to recommend through these predictions specific dietary foods to prevent elevated PPGRs that are highly variable among individuals. Additional components that can enrich the predictive algorithms are findings of nutrigenomics, nutrigenetics and metabolomics. Thus, this review aims to summarize the evidence of the components that integrate personalized nutrition focused on the prevention of PPGRs, and to show the future of personalized nutrition by laying the groundwork for the development of individualized dietary management and its impact on the improvement of metabolic diseases.

A maternal high-fat/low-fiber diet impairs glucose tolerance and induces the formation of glycolytic muscle fibers in neonatal offspring

PURPOSE

In our previous study, the maternal high-fat/low-fiber (HF-LF) diet was suggested to induce metabolic disorders and placental dysfunction of the dam, but the effects of this diet on glucose metabolism of neonatal offspring remain largely unknown. Here, a neonatal pig model was used to evaluate the effects of maternal HF-LF diet during pregnancy on glucose tolerance, transition of skeletal muscle fiber types, and mitochondrial function in offspring.

METHODS

A total of 66 pregnant gilts (Guangdong Small-ear Spotted pig) at day 60 of gestation were randomly divided into two groups: control group (CON group; 2.86% crude fat, 9.37% crude fiber), and high-fat/low-fiber diet group (HF-LF group; 5.99% crude fat, 4.13% crude fiber).

RESULTS

The maternal HF-LF diet was shown to impair the glucose tolerance of neonatal offspring, downregulate the protein level of slow-twitch fiber myosin heavy chain I (MyHC I), and upregulate the protein levels of fast-twitch fiber myosin heavy chain IIb (MyHC IIb) and IIx (MyHC IIx) in soleus muscle. Additionally, compared with the CON group, the HF-LF offspring showed inhibition of insulin signaling pathway and decrease in mitochondrial function in liver and soleus muscle.

CONCLUSION

Maternal HF-LF diet during pregnancy impairs glucose tolerance, induces the formation of glycolytic muscle fibers, and decreases the hepatic and muscular mitochondrial function in neonatal piglets.

Refined carbohydrates, phenotypic plasticity and the obesity epidemic

The major change in the United States and European diets associated with the increased rates of obesity was an increased consumption of refined carbohydrates. A feature of refined carbohydrates is their predisposition to cause increased fluctuations in plasma insulin and glucose levels and postprandial reactive hypoglycaemia. As the central nervous system is dependent on a stable supply of glucose this threatens the central nervous system functioning and these fluctuations also have a negative impact on the cardiovascular system. Phenotypic plasticity enables organisms to use adaptive phenotypes already in existence such as the increased insulin resistance and increased adiposity associated with pregnancy or the insulin resistance associated with infection, trauma and burns or to evolve new phenotypes to adapt to variations in the environment. This paper explores the evidence that increased insulin resistance that is commonly associated with increased adiposity possibly because of shared locations on the genome is a phenotypic plastic adaptation to the increased consumption of refined carbohydrates and their predisposition to cause increased fluctuations in plasma insulin and plasma glucose and post-prandial reactive hypoglycaemia both of which have negative impacts on the metabolism. Obesity, that is a relatively stable state of increased adiposity and insulin resistance has adaptive and defensive features to these fluctuations in plasma insulin and glucose in that metabolic disorders associated with refined carbohydrate consumption are often mitigated and modified as exemplified by the obesity paradox.

Postprandial lipid responses to standard carbohydrates used to determine glycaemic index values

Prior studies assessing the metabolic effects of different types of carbohydrates have focused on their glycaemic response. However, the response of postprandial cardiometabolic risk indicators has not been considered in these studies. The present study assessed postprandial lipid responses to two forms of carbohydrates used as reference foods for glycaemic index determinations, white bread (50 g available carbohydrate) and glucose (50 g), under controlled conditions and with intra-individual replicate determinations. A total of twenty adults (20–70 years) underwent two cycles of challenges with each pair of reference foods (four challenges/person), administered in a random order on separate days under standard conditions. Serum lipids (total cholesterol, LDL-cholesterol, HDL-cholesterol, TAG and NEFA), glucose and insulin were monitored for 5 h post-ingestion. Oral glucose resulted in greater glycaemic and insulinaemic responses than white bread for the first 90 min and a greater subsequent decline after 120 min (P =0·0001). The initial decline in serum NEFA concentrations was greater after the oral glucose than after the white bread challenge, as was the rebound after 150 min (P = 0·001). Nevertheless, the type of carbohydrate had no significant effect on postprandial total cholesterol, LDL-cholesterol and HDL-cholesterol concentrations. Following an initial modest rise in TAG concentrations in response to both challenges, the values dropped below the fasting values for oral glucose but not for the white bread challenge. These data suggest that the type of carbohydrate used to determine the glycaemic index, bread or glucose, has little or modest effects on postprandial plasma cholesterol concentrations. Differences in TAG and NEFA concentrations over the 5 h time period were modest, and their clinical relevance is unclear.

Changes in serum lipids and blood glucose in non diabetic patients with metabolic syndrome after mixed meals of different composition

Aims. To investigate the postprandial changes in serum lipoproteins and blood glucose and to verify whether different nutrient composition of the meal elicits different response in patients with (MetS+) and without (MetS-) metabolic syndrome. Research Design and Methods. 50 MetS+ patients and 50 age- and sex-matched MetS- consumed a regular lunch chosen among those more similar to their usual diet. Blood was drawn in the morning after 12-hour fasting and 2 and 4:30 hours after the meal. Results. Serum triglycerides increased more in MetS+ (35%, 4:30 hours after the meal) than in MetS- (29%), HDL-cholesterol decreased 2 hours after the meal in both groups (-4% and -5%, resp.). Blood sugar similarly increased in both groups (19%, 2 hours after the meal in MetS+ and 17% in MetS-) and plasma insulin increased more and remained high longer in MetS+ (73.5 and 52.3 μU/mL, 2 and 4:30 hours after the meal) than in MetS- (46.7 and 21.6 μU/mL). Difference in nutrient composition of the meal (carbohydrate 57%, fat 28% versus carbohydrate 45%, fat 35%) was not associated with differences in postprandial levels of triglycerides, HDL-cholesterol, glucose, and insulin within each group. Conclusions. As compared with MetS-, MetS+ patients show a greater hypertriglyceridemic and hyperinsulinemic response to a regular lunch whatever the carbohydrate or fat content of the meal.

Impact of early growth on postprandial responses in later life

Background

Low birth weight and slow growth during infancy are associated with increased rates of chronic diseases in adulthood. Associations with risk factors such as fasting glucose and lipids concentrations are weaker than expected based on associations with disease. This could be explained by differences in postprandial responses, which, however, have been little studied. Our aim was to examine the impact of growth during infancy on postprandial responses to a fast-food meal (FF-meal) and a meal, which followed the macro-nutrient composition of the dietary guidelines (REC-meal).

Methodology/Principal Findings

We recruited 24 overweight 65–75 year-old subjects, 12 with slow growth during infancy (SGI-group) and 12 with normal early growth. All the subjects were born at term. The study meals were isocaloric and both meals were consumed once. Plasma glucose, insulin, triglycerides (TG) and free fatty acids (FFA) were measured in fasting state and over a 4-h period after both meals. Subjects who grew slowly during infancy were also smaller at birth. Fasting glucose, insulin or lipid concentrations did not differ significantly between the groups. The TG responses were higher for the SGI-group both during the FF-meal (P = 0.047) and the REC-meal (P = 0.058). The insulin responses were significantly higher for the SGI-group after the FF-meal (P = 0.036). Glucose and FFA responses did not differ significantly between the groups.

Conclusions

Small birth size and slow early growth predict postprandial TG and insulin responses. Elevated responses might be one explanation why subjects who were small at birth and experiencing slow growth in infancy are at an increased risk of developing cardiovascular diseases in later life.