The Effect of Dairy and Non-dairy Breakfasts on Satiety and Post-meal Glycemia in Healthy Older Adults

Regular consumption of dairy is associated with better body composition and lower incidences of type 2 diabetes and obesity. This may be due to dairy's ability to increase satiety and decrease post-prandial glycemia. However, most clinical studies have only investigated isolated dairy proteins (whey and casein) and the effects of whole dairy products, consumed as part of a meal, remain unclear. Additionally, the effect of dairy type and form remain to be further investigated. Therefore, this study will test the effects of dairy products when consumed with a high glycemic index breakfast on satiety and post-prandial glycemia.

Thirty healthy older males and females (60-70 years, BMI 18.5-30.0 kg/m2) will be recruited for the randomized, unblinded, crossover study. Participants will fast overnight, and at baseline will consume 1) 2% milk (250 mL), 2) soy beverage (250 mL), 3) plain 2% Greek yogurt (175 g), 4) cheddar cheese (30 g), or 5) water (250 mL - control). Treatments will be consumed along with 2 pieces of white toast with strawberry jam, except for the water control which will be consumed alone. All breakfast meals will be isocaloric and water will be given with the yogurt (75 mL) and cheese (220 mL) to compensate for fluid content. At 0 (baseline), 15, 30, 45, 60, 90, 120, 150, 180, (pre-meal period) and 210 minutes (post-meal period) blood will be collected for glucose analysis and subjective appetite ratings completed. Insulin will be analyzed every 30 minutes. Between 180-200 minutes, an ad libitum lunch will be provided to assess food intake.

Inclusion criteria

• Healthy BMI (18.5-30.0 kg/m2)
• Regular breakfast consumers
• Menopausal for at least 1 year (females)

Exclusion criteria

• Smoking
• Diabetes
• Fasting blood glucose equal to or higher than 6.0 mmol/L
• Cardiovascular disease
• Medication affecting appetite or metabolism
• Trying to lose or gain weight through a diet or exercise regime
• Lactose intolerance or allergies to study foods
• Score equal to or higher than 11 on Eating Habits Questionnaire