Impact of Simulated Caloric Reduction on Nutrient Adequacy Among U.S. Adults with Overweight or Obesity (National Health and Nutrition Examination Survey [NHANES] 2015-2018).

BACKGROUND: Current guidelines for the treatment of obesity recommend dietary restriction to create a caloric deficit, and caloric reductions of 16% to 68% have been achieved in adults with overweight or obesity engaging in intentional weight loss programs. OBJECTIVES: This study models the impact of simulated caloric reduction on nutrient adequacy among U.S. adults ≥19 y with overweight or obesity using National Health and Nutrition Examination Survey data (2015-2018). METHODS: Four levels of caloric reduction (20%, 30%, 40%, and 50%) were modeled by prorating daily calorie intake such that usual intakes of 14 nutrients were reduced proportional to caloric reduction. The percentages below the estimated average requirement (EAR) or above the adequate intake (AI) were estimated at each level of caloric reduction, with and without dietary supplement use. Differences across percentages of simulated caloric reductions were determined using nonoverlapping confidence intervals of the means (97.5th percentile confidence intervals were used to approximate P < 0.05). RESULTS: There were significant differences (P < 0.05) in percentages below the EAR (above the AI) between sequential levels of simulated caloric reduction for most of the nutrients analyzed (protein, vitamins A, B-6, folate, and C, calcium, iron, magnesium, potassium, and zinc). For example, after a simulated 30% caloric reduction, 25%-40% of the population had intakes below the EAR for protein, vitamin B-6, and zinc, and 75%-91% of the population had intakes below the EAR for vitamin A, calcium, and magnesium (vs. 4%-18% and 45%-56%, respectively, without caloric reduction). With the inclusion of dietary supplements, percentages below the EAR for all nutrients (except protein) were lower than those for food alone. CONCLUSIONS: Caloric reduction may exacerbate nutrient inadequacies among adults with overweight or obesity. Inclusion of nutrient-dense foods, fortified foods, specially formulated products, and/or dietary supplements should be considered for those on calorie-restricted diets for long-term weight loss.

Is It Time to Reconsider the U.S. Recommendations for Dietary Protein and Amino Acid Intake?

Since the U.S. Institute of Medicine's recommendations on protein and amino acid intake in 2005, new information supports the need to re-evaluate these recommendations. New lines of evidence include: (1) re-analysis/re-interpretation of nitrogen balance data; (2) results from indicator amino acid oxidation studies; (3) studies of positive functional outcomes associated with protein intakes higher than recommended; (4) dietary guidance and protein recommendations from some professional nutrition societies; and (5) recognition that the synthesis of certain dispensable amino acids may be insufficient to meet physiological requirements more often than previously understood. The empirical estimates, theoretical calculations and clinical functional outcomes converge on a similar theme, that recommendations for intake of protein and some amino acids may be too low in several populations, including for older adults (≥65 years), pregnant and lactating women, and healthy children older than 3 years. Additional influential factors that should be considered are protein quality that meets operational sufficiency (adequate intake to support healthy functional outcomes), interactions between protein and energy intake, and functional roles of amino acids which could impact the pool of available amino acids for use in protein synthesis. Going forward, the definition of "adequacy" as it pertains to protein and amino acid intake recommendations must take into consideration these critical factors.

Substantial Depletion of Vicine, Levodopa, and Tyramine in a Fava Bean Protein-Based Nutritional Product.

A commercial fava bean protein isolate and a liquid nutritional product formulated with it were tested by validated HPLC methods for the favism-associated pyrimidine glycoside vicine, the dopamine precursor levodopa, and the biogenic amine tyramine. The vicine, levodopa, and tyramine concentrations in the protein isolate-306, 13.3, and <0.5 mg/kg, respectively-when expressed on a protein basis-34, 1.5, and <0.06 mg/100 g protein, respectively-were at least 96% lower than the vicine, levodopa, and tyramine (protein-based) concentrations reported for fava beans (≥900, ~200, and ~4 mg/100 g protein, respectively). This was also true for the vicine (13 mg/kg or 22 mg/100 g protein), levodopa (≤0.17 mg/kg or ≤0.3 mg/100 g protein), and tyramine (0.08 mg/kg or 0.14 mg/100 g protein) concentrations in the nutritional product. On the basis of these data, one serving (11 fl. oz.) of the nutritional product would deliver approximately 5 mg of vicine, <1 mg of levodopa, and <0.1 mg of tyramine.

Plant Proteins: Assessing Their Nutritional Quality and Effects on Health and Physical Function.

Consumer demand for plant protein-based products is high and expected to grow considerably in the next decade. Factors contributing to the rise in popularity of plant proteins include: (1) potential health benefits associated with increased intake of plant-based diets; (2) consumer concerns regarding adverse health effects of consuming diets high in animal protein (e.g., increased saturated fat); (3) increased consumer recognition of the need to improve the environmental sustainability of food production; (4) ethical issues regarding the treatment of animals; and (5) general consumer view of protein as a "positive" nutrient (more is better). While there are health and physical function benefits of diets higher in plant-based protein, the nutritional quality of plant proteins may be inferior in some respects relative to animal proteins. This review highlights the nutritional quality of plant proteins and strategies for wisely using them to meet amino acid requirements. In addition, a summary of studies evaluating the potential benefits of plant proteins for both health and physical function is provided. Finally, potential safety issues associated with increased intake of plant proteins are addressed.

Combination of erythritol and fructose increases gastrointestinal symptoms in healthy adults.

Consumption of a large amount of dietary fructose induces gastrointestinal intolerance, and glucose has been known as an enhancer of fructose absorption. Erythritol is a nonglycemic sugar alcohol, and it has been suggested that erythritol is absorbed paracellularly. It was hypothesized that paracellular absorption of erythritol could also enhance paracellular absorption of fructose in healthy adults. This is one of the proposed pathways for how additional glucose enhances the absorption of fructose. Thirty-seven nondiabetic, healthy adults participated in a randomized, double-masked, controlled crossover study. After an overnight fast, participants consumed beverages containing either 50 g fructose and 50 g glucose, 50 g fructose and 33.3 g erythritol (an equimolar concentration of fructose), or 50 g fructose alone. Breath hydrogen response was determined for 8 hours postprandially. Gastrointestinal intolerance symptoms and the number and consistency of bowel movements were recorded for 24 hours postprandially. The breath hydrogen area under the curve (AUC) of the fructose and erythritol beverage was 2 times the AUC of the fructose beverage and 8.75 times the AUC of the fructose and glucose beverage (P < .001, respectively). Compared with fructose and glucose beverage and fructose alone, frequency of watery stools increased (P < .05) and gastrointestinal tolerance worsened (P < .05) when participants consumed fructose and erythritol. These data suggest that coingestion of equimolar concentrations of fructose and erythritol increased carbohydrate malabsorption.

Glycemic and insulinemic responses to different preexercise snacks in participants with impaired fasting glucose.

PURPOSE: To compare serum glucose and insulin responses to 3 preexercise snacks before, during, and after exercise in individuals with impaired fasting glucose (IFG) and healthy (H) men. In addition, in an IFG population, the authors sought to determine whether a natural fruit snack (i.e., raisins) yields more desirable glucose and insulin concentrations than an energy bar or a glucose solution. METHODS: The IFG (n = 11, age = 54.5 ± 1.3 yr, fasting blood glucose [BG] = 6.3 ± 0.1 mmol/L) and H groups (n = 9, age = 48.0 ± 3.1 yr, fasting BG = 4.9 ± 0.1 mmol/L) cycled at 50% of VO2peak for 45 min on 4 occasions after consuming water or 50 g of carbohydrate from raisins (R), an energy bar (EB), or a glucose beverage (GLU). Metabolic markers were measured before, during, and after exercise. RESULTS: In all nutritional conditions, glucose concentrations of the IFG group were consistently higher than in the H group. Differences between IFG and H groups in insulin concentrations were sporadic and isolated. In the IFG group, preexercise glucose concentration was lower in the R condition than in GLU. Ten and 20 min into exercise, glucose concentrations in the R and EB conditions were lower than in GLU. Insulin concentrations were lower in the R condition than in EB and GLU immediately before exercise and at Minute 10 but at 20 min R remained lower than only GLU. CONCLUSION: Glucose concentrations were higher in the IFG group regardless of preexercise snack. Compared with the glucose solution, raisins lowered both the postprandial glycemic and insulinemic responses, whereas the energy bar reduced glycemia but not insulinemia.

Raisins are a low to moderate glycemic index food with a correspondingly low insulin index.

The objective of this study was to determine the glycemic index (GI) and insulin index (II) of raisins and evaluate if these values are similar in different populations. The study subjects consisted of 10 healthy sedentary individuals (S; age, 25.7 +/- 1.3 years; body mass index [BMI] = 23.3 +/- 1.7 kg/m(2)), 11 aerobically trained adults (A; age, 23.1 +/- 1.0 years; BMI = 24.1 +/- 0.3 kg/m(2)), and 10 prediabetic adults (P; age, 50.0 +/- 2.6 years; BMI = 32.6 +/- 1.9 kg/m(2)). Subjects consumed 50 g of available carbohydrate from raisins and from a glucose solution (reference food) on 2 separate occasions. Serum glucose and insulin concentrations were measured from capillary fingerstick blood samples at baseline and at 15, 30, 45, 60, 90, and 120 minutes (and 150 and 180 minutes for P group) postprandially. The GI of raisins was low (GI, < or = 55) in the S (49.4 +/- 7.4) and P (49.6 +/- 4.8) groups and was moderate (GI, 55-69) in the A group (62.3 +/- 10.5), but there were no differences among the subject groups (P = .437). The II of raisins was 47.3 +/- 9.4, 51.9 +/- 6.5, and 54.4 +/- 8.9 for the S, A, and P groups, respectively. On average, the A group secreted 2- to 2.5-fold less insulin per gram of carbohydrate compared with the S and P groups (P < .05). Thus, raisins are a low to moderate GI food, with a correspondingly low II. The lower insulin response in the A group compared with the other groups suggests enhanced insulin sensitivity.

Gamma-cyclodextrin lowers postprandial glycemia and insulinemia without carbohydrate malabsorption in healthy adults.

OBJECTIVE: Preliminary in vitro and animal studies have shown that gamma-cyclodextrin (GCD) is a slowly and completely digestible carbohydrate. The objective of this study was to determine the glycemic and insulinemic responses to GCD in humans. Breath hydrogen excretion was measured simultaneously to evaluate carbohydrate malabsorption. METHODS: Healthy adult subjects (N = 32) received 50 g of carbohydrate from GCD or a rapidly digested maltodextrin (MD) in a double-masked, randomized, crossover design. Plasma glucose (fingerstick) and serum insulin (venous) concentrations were measured at baseline and at 15, 30, 45, 60, 90, 120, 150, and 180 min postprandially. Breath hydrogen excretion was monitored hourly for 8 h postprandially. The severity of gastrointestinal symptoms (nausea, cramping, distension, flatulence) was rated by the subjects on a ranked scale for two 24-h periods postprandially. RESULTS: The mean baseline-adjusted peak plasma glucose concentration was 47% lower (P < 0.001), and the mean baseline-adjusted peak serum insulin concentration was decreased by 45% (P < 0.001) after subjects consumed GCD compared with MD. Positive incremental area under the curve (0-120 min) was reduced 45% for plasma glucose and 49% for serum insulin by GCD compared with MD (P < 0.001 in each case). There were no differences between GCD and MD in the proportion of positive breath hydrogen tests and both carbohydrates were equally well tolerated. CONCLUSIONS: GCD effectively lowers postprandial glycemia and insulinemia compared with MD, without resulting in appreciable carbohydrate malabsorption or gastrointestinal intolerance.

Effects of a nutritional supplement containing Salacia oblonga extract and insulinogenic amino acids on postprandial glycemia, insulinemia, and breath hydrogen responses in healthy adults.

OBJECTIVE: This study evaluated the postprandial glycemic, insulinemic, and breath hydrogen responses to a liquid nutritional product containing Salacia oblonga extract, an herbal alpha-glucosidase inhibitor, and two insulinogenic amino acids. METHODS: In a randomized, double-masked, crossover design, 43 healthy subjects were fed the following meals on separate days after overnight fasting: control (C; 480 mL of a study beverage containing 82 g of carbohydrate, 20 g of protein, and 14 g of fat), control plus 3.5 g each of phenylalanine and leucine (AA), control plus 1000 mg of S. oblonga extract (S), and control plus S and AA (SAA). Postprandially, fingerstick capillary plasma glucose and venous serum insulin levels were measured for 180 min, and breath hydrogen excretion was measured for 480 min. RESULTS: The baseline-adjusted peak glucose response was not different across meals. However, changes in plasma glucose areas under the curve (0 to 120 min and 0 to 180 min, respectively) compared with C were -9% and -11% for AA (P>0.05 each), -27% and -24% for S (P=0.035 and 0.137), and -27% and -29% for SAA (P<0.05 each). Changes in insulin areas under the curve were +5% and +5% for AA (P>0.05 each), -35% and -36% for S (P<0.001 each), and -6% and -7% for SAA (P>0.05 each). Breath hydrogen excretion was 60% greater (P<0.001) in the S-containing meals than in the C- and AA-containing meals and was associated with mild flatulence. CONCLUSIONS: Salacia oblonga extract is a promising nutraceutical ingredient that decreased glycemia in this study. Supplementation with amino acids had no significant additional effect on glycemia.

Effects of a medical food containing an herbal alpha-glucosidase inhibitor on postprandial glycemia and insulinemia in healthy adults.

OBJECTIVE: To determine the effect of different doses of Salacia oblonga extract, an herbal alpha-glucosidase inhibitor, on postprandial glycemic, insulinemic, and breath hydrogen responses in healthy adults. DESIGN: Double-masked, randomized crossover design. INTERVENTION: Subjects, after fasting for 12 hours, consumed four test meals consisting of 480 mL of study beverage (14 g fat, 82 g carbohydrate, and 20 g protein) with 0, 500, 700, or 1,000 mg of S oblonga extract on four separate occasions. Capillary finger-prick plasma glucose and venous serum insulin concentrations were measured at baseline and for 2 hours postprandially. Breath hydrogen excretion was measured at baseline and hourly for 8 hours postprandially. SUBJECTS/SETTING: Thirty-nine healthy, nondiabetic adults (body mass index=23.7+/-0.4, age=25.7+/-0.9 years. STATISTICAL ANALYSES PERFORMED: Repeated-measures analysis of variance was applied to the raw data or data that had been transformed (log, rank) when necessary due to nonnormality. The Tukey-Kramer post hoc test was used for pairwise comparisons. RESULTS: Compared with the control, the 1,000-mg S oblonga extract dose reduced the plasma glucose and serum insulin incremental areas under the curve (0 to 120 minutes postprandial) by 23% ( P =.32) and 29% ( P =.01), respectively. The other doses of S oblonga extract did not impact glycemia or insulinemia. Breath hydrogen excretion increased linearly as the dose of S oblonga extract was advanced. CONCLUSIONS: The presence of S oblonga extract tended to lower postprandial glycemia and significantly reduced the postprandial insulin response. The increase in breath hydrogen excretion suggests a mechanism similar to prescription alpha-glucosidase inhibitors. Future studies of S oblonga extract in patients with diabetes are needed.

Management of blood glucose and diabetes in the critically ill patient receiving enteral feeding.

Diabetes mellitus causes profound alterations in nutrient metabolism, leading to long-term systemic complications, particularly in individuals with poorly controlled disease. Nutrition support clinicians need to be aware of the effect of acute illness on stress-induced and established diabetes mellitus and the appropriate management strategies. Because enteral feeding is a vital component of critical care for many patients with diabetes mellitus, it is important to develop techniques to best manage metabolic control during enteral feeding. This article will review mechanics of blood glucose regulation, evaluation of energy sources for patients with diabetes mellitus, selection of enteral formulas and infusion routes, and glycemic control in patients receiving tube feeding. At this point, it is appropriate to use a standard formula to initiate feedings in most patients with blood glucose abnormalities. Close monitoring and judicious use of insulin are key in maintaining glucose control and avoiding complications.

Kefir improves lactose digestion and tolerance in adults with lactose maldigestion.

OBJECTIVE: Kefir is a fermented milk beverage that contains different cultures than yogurt. The objective of this study was to determine whether kefir improves lactose digestion and tolerance in adults with lactose maldigestion. DESIGN: Randomized block design. SUBJECTS: Fifteen healthy, free-living adults with lactose maldigestion. MAIN OUTCOME MEASURES: Breath hydrogen excretion and lactose intolerance symptoms were monitored hourly for 8 hours after each test meal. INTERVENTION: Subjects were fed test meals consisting of 20 g lactose portions of milk (2% reduced fat), plain and raspberry flavored kefir, and plain and raspberry flavored yogurt, each following an overnight (12 hour) fast. STATISTICAL ANALYSIS: Mixed model ANOVA was performed on raw or transformed data, followed by Tukey HSD post hoc tests (when appropriate). Significance was defined as P<.05. RESULTS: The breath hydrogen area under the curve (AUC) for milk (224+/-39 ppm x h) was significantly greater than for the plain yogurt (76+/-14 ppm x h, P<.001), the plain kefir (87+/-37 ppm x h, P<.001), and the flavored yogurt (76+/-14 ppm x h, P=.005). The flavored kefir had an intermediate response (156+/-26 ppm x h). The yogurts and kefirs all similarly reduced the perceived severity of flatulence by 54% to 71% relative to milk. Abdominal pain and diarrhea symptoms were negligible among the five treatments. APPLICATIONS/CONCLUSION: Because kefir improved lactose digestion and tolerance in this study, its use may be another potential strategy for overcoming lactose intolerance. Further studies of other types of kefir for improving lactose digestion are warranted.

Glycemic and insulinemic responses to energy bars of differing macronutrient composition in healthy adults.

BACKGROUND: This study investigated how energy bars of differing macronutrient composition affect postprandial glycemia and insulinemia in normal subjects compared with white bread and chicken breast controls. MATERIAL/METHODS: A total of 20 healthy adult subjects were recruited to participate in this randomized block protocol. After an overnight fast, subjects were fed 60-g portions of one of 5 meals, which were as follows: low carbohydrate bar (Atkins Advantage Bar, LC), moderate carbohydrate bar (Balance Bar, MC), high carbohydrate bar (Power Bar, HC), white bread (WB), and chicken breast (CHI). Capillary fingerstick and venous blood samples were analyzed for glucose and insulin concentrations, respectively, at baseline and at 15, 30, 45, 60, 90 and 120 minutes after start of the test meal. RESULTS: Compared with WB, plasma glucose area under the curve (AUC) for the meals was: 71% (P<0.001) lower for the LC bar, 50% (P<0.001) lower for MC bar, 4% (P=0.996) higher for the HC bar, and 83% (P<0.001) lower for the CHI. Serum insulin AUC, again compared with WB, was: 26% (P=0.497) lower for the LC bar, 35% (P=0.210) higher for the MC bar, 73% (P<0.001) higher for the HC bar, and 78% (P<0.001) lower for the CHI. CONCLUSIONS: This study demonstrated that substitution of other macronutrients for carbohydrate is effective for reducing postprandial glycemia. However, the insulin response may not decrease to the same degree and, for some bars, may actually be elevated compared with white bread.

Fructose prefeeding reduces the glycemic response to a high-glycemic index, starchy food in humans.

The study objective was to determine whether a small dose of fructose administered before or simultaneously with a high glycemic index, starchy food decreases postprandial glycemic response. Nondiabetic healthy adults (n = 31; mean +/- SEM: age, 26 +/- 1 y; weight, 66.1 +/- 2.6 kg; body mass index, 23.3 +/- 0.6 kg/m(2)) were studied in a randomized crossover design. Treatments consisted of 50 g available carbohydrate from instant mashed potatoes fed alone (control) or with 10 g fructose fed 60, 30 or 0 min before the potato meal. Capillary finger-stick blood samples were analyzed for glucose concentration at -60, -30, 0, 15, 30, 45, 60, 90 and 120 min relative to the ingestion of the potato meal. Compared with the control, the positive incremental area under the glucose curve was reduced 25 and 27% (P < 0.01) when fructose was fed either 60 or 30 min before the meal, respectively. In contrast to previous studies demonstrating that immediate administration of a small amount of fructose lowers the glycemic response to a glucose solution, we found that fructose must be consumed before a starchy food to reduce postprandial glycemia.