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Morrison Diet-Heart Study

Reduction of Mortality Rate in Coronary Atherosclerosis by a low Cholesterol-low Fat Diet. (1951) Am. Heart J. 42: 538-545.

Type Diet/Drug (Stage): Diet (2º)
Study Category: The Prevention Trials (1946-1973)
Year Begun: 1946
Location: Los Angeles, California
Principal Investigator: Morrison, Lester M.

Background/Question:

Lester M. Morrison, a practitioner in Los Angeles, was one of the earliest to explore, among his patient population, the effects of a low-cholesterol, low-fat diet on coronary mortality rates. He had taken seriously the Anitschkow animal diet experiments.

Population/Methods:

His description of the design is ambiguous but it appears that he assigned 100 cases within 6 months post-infarction who appeared sequentially in his practice to either a low-cholesterol, low-fat diet or alternately to a control not intervened upon. The population ranged in age from 32 to 70, 86 men and 14 women; hypertensives were excluded. The control group maintained their usual high-cholesterol, high-fat diet with daily fat intake ranging from 80 to 160 gm and a daily cholesterol intake between 200 and 1,800 mg. The test group maintained daily fat intake levels between 20 and 25 gm, and cholesterol intake between 50 to 70 mg per day. Vitamin supplements were given to the low-cholesterol, low-fat diet group. The groups were followed for 3 years and again at the 8th year.

Results:

After three years the test group showed a mean weight decrease from 166 lbs in men and 141 lbs in women, to 145 lbs and 124 lbs. Weight in the control group was not significantly altered. Mean serum cholesterol fell from 312 mg % to 220 in the diet group. (controls not reported). After three years the mortality rate in the control group was 30% , and in the test group 14%. After eight years the mortality rate in the test group still remained lower than in the control group, 44 % vs. 76% mortality. Patients in the treatment group described a sense of optimism, feelings of well-being and good spirits, increased exercise tolerance, increased working capacity, and decreased anginal symptoms.

Conclusions/Discussion:

While the study group was small, the randomization was flawed, and the study group not blinded, it was the first experimental test of diet and coronary experience in a substantial group of humans. Clearly, the study design was inadequate, but Morrison gets credit for innovation and priority. The study results were largely dismissed by the scientific community. (FB/HB)

References

Morrison, L.M. “Reduction of Mortality Rate in Coronary Atherosclerosis by a Low Cholesterol-Low Fat Diet.” (1951) American Heart Journal 42(4): 538-545.

Morrison, L.M. “A Nutritional Program for Prolongation of Life in Coronary Atherosclerosis.” (1955) Journal of the American Medical Association 159(15): 1425-1428.