Tutorial 1 - interpreting nutrition PDF

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Interpreting types of nutrition research studies...

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University of Melbourne Faculty of Veterinary and Agricultural Sciences

NUTR20001 Food Nutrition and Health: 2020 Tutorial 1 activity Interpreting Nutrition Research

NAME:

Zoe Lim

STUDENT ID: 1084289

The aim of this activity is to begin to get a feel of what information to look for when reading nutrition research, recognising the main points, or ‘the big picture’. Task: Students are to read the 6 attached research publication abstracts and make brief notes about the specific questions outlined for each. Note: Students are not expected to understand all of the fine detail contained in the abstracts (all of the measurements or biomarkers for example), nor are you expected to research what they are.

For each of the abstracts, while you are reading the content also think about: 1. What are the outcomes showing? 2. Do they show improved or decreased health outcomes? 3. What do the overall health outcomes mean addressing the aim of the study.

Abstract #1

Wade, AT., et al., 2017

Note, this abstract is based on a protocol (an example of methodology), ie. How the study will be carried out. There are no results or main findings. Q1. What is the aim? - to assess the cardiovascular and cognitive benefits of an altered Mediterranean diet that includes lean pork as a protein source Q2. What is the study design? - Randomized controlled trial (RCT) and cross-over design Q3. What are the groups/diets being compared? -

at-risk men and women taking modified Mediterranean diet at-risk men and women taking low-fat control diet

Q4. How long was the study? - 24 weeks Q5. Express the study design as a schematic (drawing) outlining the groups and when they are exposed to the diet(s)

Including pork in the Mediterranean diet for an Australian population: Protocol for a randomised controlled trial assessing cardiovascular risk and cognitive function.  Wade AT1 , Davis CR1 , Dyer KA1 , Hodgson JM2,3  , Woodman RJ4 , Keage HAD5 , Murphy KJ6 . Nutr J. 2017 Dec 22;16(1):84. doi: 10.1186/s12937-017-0306-x.

Abstract BACKGROUND:

The Mediterranean diet is characterised by the high consumption of extra virgin olive oil, fruits, vegetables, grains, legumes and nuts; moderate consumption of fish, poultry, eggs and dairy; and low consumption of red meat and sweets. Cross sectional, longitudinal and intervention studies indicate that a Mediterranean diet may be effective for the prevention of cardiovascular disease and dementia. However, previous research suggests that an Australian population may find red meat restrictions difficult, which could affect long term sustainability of the diet. METHODS:

This paper outlines the protocol for a randomised controlled trial that will assess the cardiovascular and cognitive benefits of a Mediterranean diet modified to include 2-3 weekly serves of fresh, lean pork. A 24-week cross-over design trial will compare a modified Mediterranean diet with a low-fat control diet in at-risk men and women. Participants will follow each of the two diets for 8 weeks, with an 8-week washout period separating interventions. Home measured systolic blood pressure will be the primary outcome measure. Secondary outcomes will include body mass index, body composition, fasting blood lipids, C-reactive protein, fasting plasma glucose, fasting serum insulin, erythrocyte fatty acids, cognitive function, psychological health and well-being, and dementia risk.

DISCUSSION:

To our knowledge this research is the first to investigate whether an alternate source of protein can be included in the Mediterranean diet to increase sustainability and feasibility for a non-Mediterranean population. Findings will be significant for the prevention of cardiovascular disease and age-related decline, and may inform individuals, clinicians and public health policy. TRIAL REGISTRATION:

ACTRN12616001046493 . Registered 5 August 2016.

Abstract # 2

Parvaresh Rizi, E., et al., 2018

Q1. What is the aim? -

to determine the satiety response of obese, insulin-sensitive Chinese men based on different macronutrient intakes (high fat, high protein or high carbohydrate)

Q2. What is the study design? - randomised cross-over study (but could also be a case-control study) Q3. How long was the study? - quick study Q4. What are the groups being compared? -

9 lean, insulin-sensitive men 9 obese, insulin-resistant men

(Note that both groups are normoglycemic) Q5. What are the meals being compared? - High protein, high fat, high carbohydrate Q6. What are the main finding(s)? -

Greater satiety and more favourable appetite hormone response with either high protein or high fat diet compared to high carbohydrate diet in the obese, insulin-resistant men.

A high carbohydrate, but not fat or protein meal attenuates postprandial ghrelin, PYY and GLP-1 responses in Chinese men. Parvaresh Rizi E1,2, Loh TP3 , Baig S1 , Chhay V1 , Huang S4 , Caleb Quek J1 , Tai ES1,2,5  , Toh SA1,2,5,6  , Khoo CM1,2  .    PLoS One. 2018 Jan 31;13(1):e0191609. doi: 10.1371/journal.pone.0191609. eCollection 2018.

Abstract It is known that the macronutrient content of a meal has different impacts on the postprandial satiety and appetite hormonal responses. Whether obesity interacts with such nutrient-dependent responses is not well characterized. We examined the postprandial appetite and satiety hormonal responses after a high-protein (HP), high-carbohydrate (HC), or high-fat (HF) mixed meal. This was a randomized cross-over study of 9 lean insulin-sensitive (mean±SEM HOMA-IR 0.83±0.10) and 9 obese insulin-resistant (HOMA-IR 4.34±0.41) young (age 21-40 years), normoglycaemic Chinese men. We measured fasting and postprandial plasma concentration of glucose, insulin, active glucagon-like peptide-1 (GLP-1), total peptide-YY (PYY), and acyl-ghrelin in response to HP, HF, or HC meals. Overall postprandial plasma insulin response was more robust in the lean compared to obese subjects. The postprandial GLP-1 response after HF or HP meal was higher than HC meal in both lean and obese subjects. In obese subjects, HF meal induced higher response in postprandial PYY compared to HC meal. HP and HF meals also suppressed ghrelin greater compared to HC meal in the obese than lean subjects. In conclusion, a high-protein or high-fat meal induces a more favorable postprandial satiety and appetite hormonal response than a high-carbohydrate meal in obese insulin-resistant subjects.

Abstract # 3 .

Weech, M,. et al.

Q1. What is the study design? What does each part of this description mean? -

Randomised controlled trial (RCT), single blind (subjects don’t know what they are receiving but researchers know), parallel group study (all carried out at the same time)

Q2. How long was the study? - 16 weeks Q3. What are the diet variables being compared? Which group is the control? - SFA-rich diet (control) - MUFA-rich diet - PUFA-rich diet Q4. Express the study design as a schematic (drawing)

Q5. What are the main finding(s)? Consider what the P-values and state if the difference between the groups is real.

-

MUFA and PUFA decreased EMP by 47.3% and 44.9% respectively MUFA and PUFA decreased PMP by 36.8% and 39.1% respectively MUFA increased EPC by 28.4% P < 0.01 which implies that results are significant (99.9% probability)

Replacement of dietary saturated fat with unsaturated fats increases numbers of circulating endothelial progenitor cells and decreases numbers of microparticles: findings from the randomized, controlled Dietary Intervention and VAScular function (DIVAS) study.  Weech M1, Altowaijri H1 , Mayneris-Perxachs J1 , Vafeiadou K1 , Madden J1 , Todd S2 , Jackson KG1 , Lovegrove JA1, Y  aqoob P1. Am J Clin Nutr. 2018 Jun 1;107(6):876-882. doi: 10.1093/ajcn/nqy018.

Abstract BACKGROUND:

Endothelial progenitor cells (EPCs) and microparticles are emerging as novel markers of cardiovascular disease (CVD) risk, which could potentially be modified by dietary fat. We have previously shown that replacing dietary saturated fatty acids (SFAs) with monounsaturated or n-6 (ω-6) polyunsaturated fatty acids (MUFAs or PUFAs, respectively) improved lipid biomarkers, blood pressure, and markers of endothelial activation, but their effects on circulating EPCs and microparticles are unclear. OBJECTIVE:

The Dietary Intervention and VAScular function (DIVAS) Study investigated the replacement of 9.5-9.6% of total energy (%TE) contributed by SFAs with MUFAs or n-6 PUFAs for 16 wk on EPC and microparticle numbers in United Kingdom adults with moderate CVD risk. DESIGN:

In this randomized, controlled, single-blind, parallel-group dietary intervention, men and women aged 21-60 y (n = 190) with moderate CVD risk (≥50% above the population mean) consumed 1 of three 16-wk isoenergetic diets. Target compositions for total fat, SFAs, MUFAs, and n-6 PUFAs (%TE) were as follows: SFA-rich diet (36:17:11:4; n = 64), MUFA-rich diet (36:9:19:4; n = 62), and n-6 PUFA-rich diet(36:9:13:10; n = 66). Circulating EPC, endothelial

microparticle (EMP), and platelet microparticle (PMP) numbers were analyzed by flow cytometry. Dietary intake, vascular function, and other cardiometabolic risk factors were determined at baseline. RESULTS:

Relative to the SFA-rich diet, MUFA- and n-6 PUFA-rich diets decreased EMP (-47.3%, -44.9%) respectively and PMP (-36.8%, -39.1%) numbers (overall diet effects, P < 0.01). The MUFA-rich diet increased EPC numbers (+28.4%; P = 0.023). Additional analyses that used stepwise regression models identified the augmentation index (measuring arterial stiffness determined by pulse-wave analysis) as an independent predictor of baseline EPC and microparticle numbers. CONCLUSIONS:

Replacement of 9.5-9.6%TE dietary SFAs with MUFAs increased EPC numbers, and replacement with either MUFAs or n-6 PUFAs decreased microparticle numbers, suggesting beneficial effects on endothelial repair and maintenance. Further studies are warranted to determine the mechanisms underlying the favorable effects on EPC and microparticle numbers after SFA replacement. This trial was registered at www.clinicaltrials.gov as NCT01478958.

Abstract # 4 Sakurai, M., et al,. 2018 Q1. What is the aim? - to investigate the relationship between macronutrient intake and socioeconomic status Q2. What is the study design? - cohort study, cross-sectional (exposure and outcome both measured at the same point in time) Q3. What type of study is this design? - epidemiological (cross-sectional study) Q4. What data is being compared? -

SES (equivalent household expenditure) macronutrient intake

Q5. What outcomes can be determined? - higher household income associated with greater fat intake and lower carbohydrate intake Q6. What are the main finding(s)? - those of older age were found to consume more carbohydrates and less fat

Macronutrient Intake and Socioeconomic Status: NIPPON DATA2010.  Sakurai M1 , Nakagawa H2 , Kadota A3,4  , Yoshita K5 , Nakamura Y6 , Okuda N7 , Nishi N8 , Miyamoto Y9 , Arima  kayama A13, Miura K3,4. H10, Ohkubo T11, Okamura T12, Ueshima H3,4, O J Epidemiol. 2018;28 Suppl 3:S17-S22. doi: 10.2188/jea.JE20170250.

Abstract BACKGROUND:

This study examined the relationships among household income, other SES indicators, and macronutrient intake in a cross-sectional study of a representative Japanese population. METHODS:

In 2010, we established a cohort of participants in the National Health and Nutrition Survey (NHNS) from 300 randomly selected areas throughout Japan. A total of 2,637 participants (1,145 men and 1,492 women) were included in the study. Data from NHNS2010 and the Comprehensive Survey of Living Conditions 2010 (CSCL2010) were merged, and relationships among macronutrient intake and SES were evaluated. Additionally, socioeconomic factors associated with a risk of a higher carbohydrate/lower fat intake beyond dietary recommendations were evaluated. RESULTS:

Household income was positively associated with fat intake (P = 0.001 for men and...