Saturated Fat and Heart Disease

This page contains information taken from Dr. Peter Attia’s presentation entitled Readdressing Dietary Guidelines given on January 28, 2015.

The available evidence from cohort and randomized controlled trials is unsatisfactory and unreliable to make judgment about and substantiate the effects of dietary fat on risk of CHD.

FAO/WHO Expert Consultation background paper, 2009

Meta-analysis written by a group from Oakland Children’s Hospital under Ron Krauss, who is one of the three biggest thought-leaders on cardiovascular disease…

A meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD.

Siri-Tarino et al. American Journal of Clinical Nutrition, 2010

A very large meta-analysis of 49 observational trials with about half a million subjects and 27 randomized controlled trials with more than 100,000 patients…

Current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of total saturated fats.

Chowdhury et al. Annals of Internal Medicine, 2014

Important studies

United States Senate Select Committee on Nutrition and Human Needs

This was a select committee of the United States Senate between 1968 and 1977. It was sometimes referred to as the McGovern committee, after its only chairman, Senator George McGovern of South Dakota.

Recommendation #1 –

Increase carbohydrate consumption to 55-60% of calories.

Recommendation #2 –

Reduce fat consumption to 30% of calories.

The Framingham Heart Study is a long-term, ongoing cardiovascular cohort study of residents of the city of Framingham, Massachusetts. The study began in 1948 with 5,209 adult subjects from Framingham, and is now on its third generation of participants. Prior to the study almost nothing was known about the epidemiology of hypertensive or arteriosclerotic cardiovascular disease. Much of the now-common knowledge concerning heart disease, such as the effects of diet, exercise, and common medications such as aspirin, is based on this longitudinal study. It is a project of the National Heart, Lung, and Blood Institute, in collaboration with (since 1971) Boston University.

Minnesota Coronary Study (1973),

Frantz, Principal Investigator

• Well-designed study.

• Studied 9,000 men and women in 6 mental institutions (where diet was controlled) over 4 1/2 years.

• Treatment group:

  • 9% SF intake (treatment group),

  • Total cholesterol in treatment group went from 207 to 175

  • 269 deaths

• Control group:

  • 18% SF intake (control group)

  • Total cholesterol in control group went from 207 to 203

  • 206 deaths

• After 4 1/2 years, cholesterol decreased significantly in the treatment group, but there was no difference at all in heart disease or overall mortality.

• NOTE: The results weren’t published until 16 years later because they were “disappointing.”

Jerry Reaven from Stanford University observed something in the mid 1990’s. There is a cluster of metabolic findings that predict heart disease, diabetes, stroke, cancer, and Alzheimer’s disease far better than anything else.

• Truncal obesity

• Elevated blood pressure

• Elevated glucose

• Low HDL

• High triglyceride

This was called Syndrome X and is known today as metabolic syndrome. If you have 3 of the 5 findings in the list, your risk for metabolic diseases goes through the roof.

The Multiple Risk Factor Intervention Trial (MRFIT), 1982

• Dietary intervention study

• Cost: $115,000,000

• 13,000 high risk men age 35-57

• Two groups

• Intervention/treatment group:

  • Stop smoking

  • Given medicine to control blood pressure

  • Told to consume a low fat, low cholesterol diet

• Control group: no changes

• 7 year mortality:

  • 41.2/1,000 (intervention) vs. 40.4/1,000 (control)

• No significant difference

The Lipid Research Clinics Coronary Primary Prevention Trial (LRC-CPPT), 1984

• Cost: $150,000,000

• 3,800 men with elevated cholesterol, asymptomatic

• Two groups (double blind study)

• Intervention/treatment group:

  • Eat low fat, low cholesterol diet

  • Given medicine: bile acid sequestrant

• Control group: placebo

• 10 year mortality:

  • 35.8/1,000 (intervention) vs. 37.3/1,000 (control)

• Results were statistically significant, but clinically insignificant.

• Hailed as “Sorry, it’s true. Cholesterol really is a killer” by Time Magazine.

• The NIH consensus conference concluded –

  • There is “no doubt” that a low-fat diet “will afford significant protection against coronary heart disease” to every American over the age of two.

1989 – National Academy of Sciences Diet and Health: Implications for Reducing Chronic Disease Risk (1,300 pages)

“Highest priority is given to reducing fat intake, because the scientific evidence concerning dietary fats and other lipids and human health is strongest and the likely impact on public health the greatest.”

Evidence, Post-consensus

1990 – today

Meta-Analyses (2001)

Cochrane Colalboration: “Reduced or modified dietary fat for preventing cardiovascular disease”

• 27 well-controlled randomized trials

• 10,000 subjects

• Followed for an average of 3 years each

• No effect on longevity.

• No “significant effet on cardiovascular events.”

Meta-Analyses (2006)

Cochrane Colalboration: “Multiple risk factor interventions for primary prevention for coronary heart disease”

• Multiple interventions include lowering blood pressure and cholesterol

• 10 well-controlled trials

• 900,000 patient years of observation

• “The pooled effects suggest multiple risk factor intervention has no effect on mortality.”

Meta-Analyses (2011)

Cochrane Colalboration: “Multiple risk factor interventions for primary prevention for coronary heart disease” [updated]

• Multiple interventions include lowering blood pressure and cholesterol

• 55 trials of 6 to 12 month duration

• “Contrary to expectations, multiple risk factor interventions had little or no impact on the risk of coronary heart disease mortality or morbidity.”

Women’s Health Initiative (2006)

• 48,835 post-menopausal women randomized to a low-fat diet or a control diet (60/40)

• After six years, total fat consumption was reduced by 8.2%; saturated fat was reduced by 2.9%

• “Modest” increases in fruits, vegetables and whole grains

• Average follow-up was 5 1/2 to 7 years

• “The intervention did not reduce risk of CHD or stroke.”

• “A low-fat dietary pattern did not result in a statistically significant reduction in the risk of invasive breast cancer…”

• “There is no evidence that a low-fat dietary pattern intervention reduces colorectal cancer risk…”

• “A low-fat dietary pattern among generally healthy postmenopausal women showed no evidence of reducing diabetes risk…”

Caveat

Drugs and diets are not comparable.

Drugs have multiple actions as do diets.

Saying that statins reduce heart disease risk by lowering cholesterol, is like saying that aspirin reduces heart disease risk by reducing headaches.

Richard Kronmal, University of Washington