Dietary Fat Guidelines Deemed Unsubstantiated


While national recommendations on fat consumption might have influenced patients' dietary habits, a new study found insufficient evidence to support those guidelines.

While national recommendations on fat consumption might have influenced patients’ dietary habits, a new study found insufficient evidence to support those guidelines.

The dietary recommendations were introduced by the United States in 1977 and the United Kingdom in 1983 in an effort to combat coronary heart disease (CHD). Both guidelines advised patients to reduce their saturated fat consumption to 10% of total energy intake and their overall fat consumption to 30% of total energy intake.

Of note, the US and UK governments acknowledged that the evidence supporting these recommendations was inconclusive.

Seeking to review this evidence, a recent Open Heart study described a meta-analysis of the randomized control trial (RCT) data that would have been available to US and US regulatory committees during the creation of their respective guidelines.

The research team identified 6 trials published prior to 1983 that examined the relationships among dietary fat, serum cholesterol, and CHD. After evaluating the results of these trials, the researchers made the following observations:

  • The 6 studies enrolled a total of 2467 participants, all of whom were men.
  • Only 1 of those RCTs took the overall or saturated fat recommendations into consideration.
  • 5 of the trials focused on secondary prevention of CHD.
  • There were 740 total deaths, 423 of which resulted from CHD.
  • There were an equal number of deaths in the treatment and control groups, with 370 reported in each.
  • There was no significant difference in the number of deaths from CHD, with 207 in the treatment groups and 216 in the control groups.
  • Patients in the treatment groups experienced a significant reduction in serum cholesterol compared with patients in the control groups, but this did not seem to impact the death rates from all causes or CHD.

None of the trials tested the dietary recommendations or suggested the establishment of fat consumption guidelines, according to the research team.

Practice Points

Given this study’s challenges to commonly accepted dietary guidelines, patients might have questions regarding their fat consumption and other eating habits. In an exclusive interview with Pharmacy Times, study co-author James J. DiNicolantonio, PharmD, of Saint Luke's Mid America Heart Institute, offered the following counseling recommendations:

  • Do not demonize any macronutrient—including saturated fat—that comes from whole food.
  • Patients who are reducing their animal fat intake should be careful about what replaces that fat; while replacing it with vegetable oils or refined carbs will likely lead to worse health outcomes, replacing it with omega-3s or olive oil may provide an overall health benefit.
  • Patients should not be overly focused on “surrogate markers” such as their cholesterol level or low-density lipoprotein (LDL) level, as these numbers are not enough to tell a complete story about the patient’s health. For example, while saturated fats seem to raise large buoyant LDL, they are also likely lower small dense LDL and reduce oxidized LDL.

Dr. DiNicolantonio summed up his dietary advice in 3 words: “Eat real food.”

“From the literature available, it is clear that at the time dietary advice was introduced…no women had been studied; no primary prevention study had been undertaken; no RCT had tested the dietary fat recommendations; no RCT concluded that dietary guidelines should be introduced,” the study authors wrote. “It seems incomprehensible that dietary advice was introduced for 220 million Americans and 56 million UK citizens, given the contrary results from a small number of unhealthy men.”

The authors also pointed to a 1977 conversation between Dr. Robert Olson of St. Louis University and Senator George McGovern (D-SD), chair of the Dietary Committee. When Dr. Olson emphasized that additional research must be conducted before dietary recommendations can be introduced, Sen. McGovern responded with, “Senators don’t have the luxury that the research scientist does of waiting until every last shred of evidence is in.”

“There was best practice, RCT evidence available to the dietary committees, which was not considered and should have been,” the authors wrote. “The results of the present meta-analysis support the hypothesis that the available RCTs did not support the introduction of dietary fat recommendations in order to reduce CHD risk or related mortality.”

The study authors ultimately concluded that “dietary advice not merely needs review; it should not have been introduced.”

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