Nutritional biomarkers comparing a healthy versus a typical Australian diet: a Feeding Study in Australian Adults.

INTERVENTION: The Healthy Australian Diet (HAD) will provide foods to adequately meet the recommended servings of the 5 core food groups according to the current Australian Dietary Guidelines for adults e.g., 5.5 servings of grains/cereals; 5 servings of vegetables/legumes/beans; 2 servings of fruit; 3 servings of milk/yoghurt/cheese/alternatives and 2.5 servings of lean meats/alternatives. The diet aims to meet the Acceptable Macronutrient Distribution Ranges (AMDR) e.g., 15‐25% energy from protein, 45‐65% energy from carbohydrates, 20‐35% energy from fat; less than or equal to 10% energy from saturated fat and less than or equal to 1% energy from trans fat. Some emphasis will be given to specific nutrient targets such as fibre, free sugars, and sodium. Fruits and vegetables that are rich in beta‐carotene (e.g., carrots, pumpkin, tomatoes, red capsicum, and sweet potato) will be emphasized during this dietary pattern. Characteristics of the food choices will reflect a high diet quality consistent with recommendations in the Australian Dietary Guidelines. All meals and snacks are provided to participants for the duration of both 2‐week diet intervention phases. This includes pre‐prepared main meals (e.g., ready made fresh meals or frozen meals), fresh produce, cereals and snacks. Study investigators calorie‐match the foods (to the participants baseline usual calorie intake) to be provided which are placed as a grocery order by the study investigators during the final appointment with the participants at the preceding phase. Participants collect the pre‐ordered and pre‐paid grocery items at their nearest allocated supermarket chain. The dietary intervention has been designed by and will be monitored by study coordinators who are also accredited practising dietitians. Partici CONDITION: Cardiovascular ‐ Other cardiovascular diseases Diet and Nutrition ‐ Other diet and nutrition disorders Diet‐related cardiovascular disease; ; Diet‐related cardiovascular disease PRIMARY OUTCOME: Plasma metabolites (exploratory outcome)[Baseline (end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] Urinary metabolites (exploratory outcome)[Baseline (end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] SECONDARY OUTCOME: % body fat using bioelectrical impedance will be measured by study coordinators (research Dietitians)[Baseline (Week 2, end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] Appetite and hunger scale (Visual Analogue Scale, VAS)[Weekly. ; Baseline (Week 1 & Week 2 ‐ Run‐in phase), Week 3 & 4 (diet phase 1), Week 5&6 (end of washout) and Week 7 & 8 (end of diet phase 2).] Arterial stiffness measured using Cardioscope[Baseline (Week 2, end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] Blood pressure (Systolic/diastolic) using an automatic blood pressure monitor[Baseline (Week 2, end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] Body weight using bioelectrical impedance will be measured by study coordinators (research Dietitians) in weeks 2, 4, 6 and 8 and by participants at home using their own set of scales in weeks 3, 5 and 7.[Weekly. ; Baseline (Week 1 & Week 2 ‐ Run‐in phase), Week 3 & 4 (diet phase 1), Week 5&6 (end of washout) and Week 7 & 8 (end of diet phase 2).] Faecal flora measured via faecal sample culture (exploratory outcome)[Baseline (Week 2, end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] Fasting blood glucose[Baseline (end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] Fasting lipid profile (total cholesterol, LDL‐cholesterol, HDL‐cholesterol, triglycerides, total choleserol:to:HDL cholesterol ratio) in blood.[Baseline (end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] Fat free mass using bioelectrical impedance will be measured by study coordinators (research Dietitians)[Baseline (Week 2, end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] Fat mass using bioelectrical impedance will be measured by study coordinators (research Dietitians)[Baseline (Week 2, end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] Genetic risk score quantified from blood samples which will have their DNA extracted to be genotyped[Baseline (end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] Physical activity (Active Australia Survey)[Baseline (Week 2, end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] Plasma carotenoids[Baseline (end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] Plasma fatty acids[Baseline (end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] Qualitative dietary intake (Australian Eating Survey)[Baseline (end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] Quantitative dietary intake (24‐hr recall)[Weekly. ; Baseline (Week 1 & Week 2 ‐ Run‐in phase), Week 3 & 4 (diet phase 1), Week 5&6 (end of washout) and Week 7 & 8 (end of diet phase 2).] Skeletal muscle mass using bioelectrical impedance will be measured by study coordinators (research Dietitians)[Baseline (Week 2, end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] Skin carotenoids will be measured using a CM700D spectrophotometer (Konica Minolta) with an 8‐mm diameter aperture, 2‐degree observer angle, and illuminant D65. Skin colour (CIE L*a*b* values, where positive L*, a* and b* values represent lightness, redness, and yellowness, respectively) will be recorded for each participant on the waist or arm and repeated 3 times at each site.[Baseline (Week 2, end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] Waist circumference using a tensible tape measure[Baseline (Week 2, end of run‐in phase), Week 4 (end diet phase 1), Week 6 (end of washout) and Week 8 (end of diet phase 2).] INCLUSION CRITERIA: • Healthy adults (aged 18 years and older) • Currently taking no medications or are on stable medication therapy for the last 3 months • Willing to adhere to strict diet protocol for 8 weeks • Access to a smart phone or tablet with access to the internet • In the Newcastle region for at least the entirety of the two feeding intervention periods