Page 18 - Spring2012

Six but Time nevertheless ran a cover story entitled Two of them found that vegetable oils increased
12, 14
randomized, “Hold the Eggs and Butter,” which artfully fea- the risk of heart disease, although one of these
tured a frowning face with eyes of sunnyside creatively concluded from this that “men who
controlled up eggs and a downturned mouth of a slice of have had myocardial infarction are not a good
trials fried bacon. The article declared, “cholesterol choice for testing the lipid hypothesis.” Two of
14
specifically is proved deadly, and our diet may never be the them reported no effect of vegetable oil. 13, 15 The
same.”
authors of one of these two trials, however, only
10
testing the In our own day, the American Heart As- reported the results half-way through the study. 15
effect of the sociation continues to promote the hypothesis In the final report, they pooled the two groups
substitution with vigor. In 2009, it updated its official stance, together and compared them to a new control
recommending at least 5 to 10 percent of calo-
group that had not received any dietary advice
of poly- ries as omega-6 PUFA with additional PUFA at all. As a result, we have no way of knowing
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unsaturated coming from omega-3 sources, and concluded the true effect of vegetable oil in that study. Two
vegetable oils that intakes even higher than this “appear to be of the six trials were double-blind, and deserve
safe and may be even more beneficial (as part special attention.
These are the Minnesota
16, 17
for animal of a low-saturated fat, low-cholesterol diet).” 11 Coronary Survey and the Los Angeles Veterans
fats on heart It was one thing to promote this hypothesis in Administration Hospital Study.
disease have 1961 when it had never been tested, but to throw The Minnesota Coronary Survey tested the
a PUFA party in 2009 and suggest we all wash effect of substituting vegetable oils for animal
been away our cardiovascular concerns with swigs of fats in hospital patients who were on the diets
published. soybean oil is to ignore with callow abandon all for an average duration of only one year. As
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the lessons we have learned from clinical trials shown in Figure 2, vegetable oil had no effect
published in the intervening decades. on cardiovascular disease. While its effect on
Six randomized, controlled trials spe- total mortality was not statistically significant,
cifically testing the effect of the substitution of however, total survival was nevertheless better
polyunsaturated vegetable oils for animal fats in the group eating saturated fat. We naturally
on heart disease have been published. 12-17 These must wonder what would have happened to total
trials were all published between 1965 and 1989. mortality had the subjects been on the diets for

CVD-Free Survival Total Survival
FIGuRe 2. Vegetable Oil Produced a Statistically Insignificant but Nevertheless unfavorable Trend in Total Mortality
in the Minnesota Coronary Survey. 16

The dotted line represents the survival of the group eating a diet rich in saturated fat, whereas the solid line represents
the survival of the group eating a diet rich in PuFA. Although the duration of the graphs extends up to 4.5 years, subjects
were continually entering and exiting the study, so that the average subject was on the diet for only one year. The graphs
exaggerate the difference between the two lines because the vertical axes do not begin at zero. Nevertheless, the trend for
total survival, though not statistically significant, favors the saturated fat group.
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