Dietary Incorporation of Lentils to Improve Metabolic Health
Condition: Waist, Hypertriglyceridemic
MeSH terms: Hypertriglyceridemic Waist
Study type: Interventional

Summary: 
      Approximately 40% of Americans are pre-diabetic or diabetic, mostly in the form of type 2
      diabetes (T2D), which is heavily influenced by diet. Three interrelated factors driving the
      progression of T2D are large glycemic and lipidemic responses after a meal, consumption of
      excess calories, and increased fat within the abdominal compartment, referred to as visceral
      adipose tissue (VAT). Available research suggests that these problems may be attenuated with
      pulse consumption both at the time of consumption and at the next meal, in what is referred
      to as the second meal effect. Associations between pulse consumption and metabolic health
      have been measured in observational studies; unfortunately, randomized clinical trials data
      to establish cause and effect in humans are typically short in duration (≤ 4 weeks), limited
      to a single dose of pulse consumption (none exclusively for lentils), and not designed to
      strategically exploit the well-established second meal effect. We expect the impact of lentil
      intake will be greatest if consumed at the midday meal to offset the magnitude of the
      response to the large caloric intake typical in the evening. Our overarching hypothesis is
      that midday lentil consumption in individuals at greater risk for metabolically driven
      diseases will improve metabolic health. The purpose of this proposal is to determine whether
      eight weeks of 0, 300, or 600 grams per week of lentils by individuals with elevated VAT will
      improve insulin sensitivity, hepatic insulin resistance, lipid profiles (total cholesterol,
      triglycerides, LDL and HDL lipoproteins), inflammation, appetite and satiety, body mass, body
      composition, and volume of VAT.
    

Detailed description: 
      Investigators utilized a parallel intervention of two separate dietary lentil doses versus
      control (no lentils) treatments for eight weeks in adults with elevated waist circumference.
      Enrolled participants were randomized to LOW (300 g lentils/week), HIGH (600 g lentils/week),
      or CONTROL (0 g lentils/week) treatment groups using block randomization. Outcome variables
      were assessed before and after 8 weeks of the dietary intervention.

      Procedures:

      Anthropometrics. Measurements were collected from participants before and after the
      intervention using the validated segmental multifrequency bioelectrical impedance analysis
      (SECA mBCA515, Hamburg, Germany) (cite). Fat mass (%) and estimated visceral adipose (L) were
      used for analysis.

      Glycemic Challenge. An oral glucose tolerance test (OGTT) was administered as a meal which
      contained white bread containing 75 g or available carbohydrate. Water was provided with the
      meal. Caffeinated black tea was provided for participants who identified as habitual morning
      caffeine consumers. Participants were instructed to avoid alcohol consumption and strenuous
      physical activity in the 24 hours before their visit and to complete an overnight fast (10
      -12 hours) before blood collection. Fasting blood samples were collected by venipuncture by a
      trained phlebotomist before ingestion of the glycemic challenge meal. A fingerstick was used
      to obtain blood for glucose and insulin prior to ingestion of bread and every 30 minutes in
      the 2-hour postprandial period.

      Dietary Intervention: Experimental diets were provided to participants in the form of five
      pre-made midday meals containing 0, 60, or 120 g per meal matched across treatment groups for
      total energy and protein. Midday meals were targeted in this study to exploit the second meal
      effect of lower caloric intake at the next meal, the evening meal. Participants were
      instructed to consume all of the meal provided to them at the midday meal and then
      proactively reduce portion sizes and not eat beyond fullness at the evening meal.
      Participants were instructed to eat the meals Monday through Friday, and to eat any missed
      meals on Saturday or Sunday. Compliance was checked with random emails once per week and
      verbal reporting when picking up weekly meals.

      Assessment of Satisfaction with Meal Provided: An email or text message questionnaire was
      sent to each participant for them to complete in real time at 4:00 pm one evening per week.
      Day of the week was varied so that each of the five weekdays was sampled at least once.
      Participants were asked to rate the following question "How much do you like your meal
      provided today?" on a scale from 1 (dislike extremely) to 9 (like extremely).

      Assessment of Satiety: An email or text message questionnaire was sent to each participant
      for them to complete in real time at 4:00 pm one evening per week. Day of the week was varied
      so that each of the five weekdays was sampled at least once. To assess the elements of
      satiety, participants rated each of the following questions on a scale of 0 to 10: How hungry
      are you? (0 = not at all, 10 = extremely); How full are you? (0 = not at all, 10 =
      extremely); How satisfied do you feel? (0 = not at all, 10 = extremely); How strong is your
      desire to eat? (0 = very weak, 10 = very strong); How much do you think you could (or would
      want to) eat right now? (0 = nothing, 10 = very large amount)

      Assessment of Gastrointestinal Comfort: An email or text message questionnaire was sent to
      each participant for them to complete in real time at 8:00 pm one evening per week. Day of
      the week was varied so that each of the five weekdays was sampled at least once. To assess
      gastrointestinal comfort, participants rated the following symptoms as none, mild, moderate,
      or severe: flatulence, bloating, cramping, abdominal discomfort.

      Blood analysis: Whole blood in serum separating tubes was allowed to clot for 15 minutes
      before centrifugation at 1200 RPM for 15 minutes with resulting serum aliquoted and stored at
      -80ºC until analysis.Determination of blood markers. Blood markers of metabolic syndrome as
      defined by the World Health Organization were determined from whole blood run on Picollo
      Xpress Chemistry Analyzer lipid panels (Abaxis, Union City, USA). Glycated hemoglobin (HbA1c)
      was determined using the DCA Vantage Analyzer (Siemens Medical Solutions Diagnostics,
      Cergy-Pontoise, France) performed according to manufacturer instructions. Insulin
      concentrations from fasting and postprandial samples were determined through a
      high-sensitivity insulin ELISA kit according to manufacturer instructions (ALPCO, Salem, NH,
      United States). Fasting insulin and glucose concentrations were used to calculate homeostasis
      model assessment of insulin resistance (HOMA-IR). The Matsuda Index was calculated from
      fasting and postprandial glucose and insulin concentrations. The postprandial glucose and
      insulin concentrations in response to the OGTT were input into the incremental area under the
      curved (AUC) method.
    

Intervention name(s): Dietary Lentil Intake; No Dietary Lentil CONTROL
Intervention type(s): Behavioral; Behavioral
Intervention description(s): Dietary intake of moderate or high dose of lentils at midday meals; Dietary intake of meals without lentils and matched to dietary lentil meals for total energy and protein
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: This study utilized a parallel intervention of meals with 0, 60 or 120 g of lentils 5 days per week for 8 in overweight or obese adults with elevated waist circumference.
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: glycemic control; inflammation; triglyceride; satiety; gastrointestinal comfort; pulse crop; lentil