Lecture 38

Case Study: Health

DATA 8

Fall 2017

Slides created by John DeNero (denero@berkeley.edu) and Ani Adhikari (adhikari@berkeley.edu)

Announcements

Introduction

(Excerpt 2:45)

Malcolm Gladwell

• Author (Blink, The Tipping Point) & journalist (New Yorker)
• "Revisionist History will go back and reinterpret something from the past: an event, a person, an idea. Something overlooked. Something misunderstood."
• You should listen to the whole episode: �Season 2, Episode 10

http://revisionisthistory.com/episodes/20-the-basement-tapes

The Diet-Heart Hypothesis

Cardiovascular Disease

• Atherosclerosis narrows arteries due to plaque buildup.
• #1 cause of death and disability in the developed world.
• Cardiovascular disease (CVD) is the leading global cause of death: 17.3 million deaths per year.
• The causes are not known, but there are associations with high blood pressure, diabetes, smoking, obesity, family history, age, inactivity, and an unhealthy diet.

​

https://www.nhlbi.nih.gov/health/health-topics/topics/atherosclerosis/atrisk

Diet & Cardiovascular Disease

• 1.7M deaths worldwide are attributed to low fruit and vegetable consumption by the WHO (2011).
• High intake of salt is linked to high blood pressure.
• High intake of processed foods is linked to obesity.
• Eliminating trans fats is widely recommended.
• Added sugar is linked to high blood pressure & obesity.
• High intake of alcohol is associated with CVD risk.

http://www.who.int/cardiovascular_diseases/publications/atlas_cvd/en/

The Diet-Heart Hypothesis

Hypothesis:

• Replacing saturated fat (e.g. dairy) with polyunsaturated fat (e.g. plant-based oil) reduces risk of heart disease.

Justification:

• This replacement reduces serum cholesterol.
• Serum cholesterol is associated with heart disease.
• "Clinical trials that used polyunsaturated fat to replace saturated fat reduced the incidence of CVD." (AHA, 2017)

http://circ.ahajournals.org/content/early/2017/06/15/CIR.0000000000000510

Hypothesis Testing

Designing an Experiment

Hypothesis:

• Replacing saturated fat (e.g. dairy) with polyunsaturated fat (e.g. plant-based oil) reduces risk of heart disease.

What evidence would support this hypothesis?

Attendance

bit.ly/attend8

Minnesota Coronary Experiment�(1968-1973)

(Excerpt 11:10)

Broste Thesis Figure 6

(Demo)

(Excerpt 3:35)

http://www.psych.uic.edu/download/Broste_thesis_1981.pdf

Broste Thesis Figures

Other Clinical Trials

Controlled Experiments

• Wadsworth Hospital and Veterans Administration Center in Los Angeles evaluated a diet [using] corn, soybean, safflower, and cottonseed oils, all high in polyunsaturated linoleic acid, to replace saturated fat in the control diet (846 men; mean age of 65 years; 30% had CVD; 8 year duration).
• Oslo Diet-Heart Study evaluated changing to a low saturated, high polyunsaturated fat diet (412 men with prior MI).
• British Medical Research Council compared a diet containing soybean oil, 86 g/d, with a diet with saturated fat from animal products (393 men with prior MI).

http://circ.ahajournals.org/content/early/2017/06/15/CIR.0000000000000510

Finnish Mental Hospital Study

"The Finnish Mental Hospital Study compared a diet high in polyunsaturated fat, mainly from soybean oil, with a diet high in saturated fat in 1222 patients at 2 psychiatric hospitals. In 1 hospital, the high polyunsaturated fat diet was given first, followed by the saturated fat diet; in the other hospital, the diets were given in the reverse order (1222 patients; 6 years)."

• Non-blind & conditions evaluated at different times.
• "The amount of sugar in the diet varied by almost 50%."
• "The use of psychiatric drugs with known cardiovascular side effects differed substantially between groups."

http://circ.ahajournals.org/content/early/2017/06/15/CIR.0000000000000510�http://wholehealthsource.blogspot.com/2009/07/finnish-mental-hospital-trial.html