‘Closer monitoring needed’
“Our results have shown, I think for the first time, that there is an association between this increasingly popular dietary pattern and high LDL cholesterol and an increased future risk of cardiovascular events,” senior author Liam Brunham, MD, of the University of British Columbia, said in an interview. “This is concerning as there are many people out there following this type of diet, and I think it suggests there is a need for closer monitoring of these people.”
He explained that while it would be expected for cholesterol levels to rise on a high-fat diet, “there has been a perception by some that this is not worrisome as it is reflecting certain metabolic changes. What we’ve shown in this study is that if your cholesterol does increase significantly on this diet then you should not assume that this is not a problem.
“For some people with diabetes this diet can help lower blood sugar and some people can lose weight on it,” he noted, “but what our data show is that there is a subgroup of people who experience high levels of LDL and ApoB and that seems to be driving the risk.”
He pointed out that overall the mean level of LDL was only slightly increased in the individuals on the low-carb/high-fat diet but severe high cholesterol (more than 5 mmol/L or 190 mg/dL) was about doubled in that group (10% vs. 5%). And these patients had a sixfold increase in risk of cardiovascular disease (P < .001).
“This suggests that there is a subgroup of people who are susceptible to this exacerbation of hypercholesterolemia in response to a low-carb/high-fat diet.”
Dr. Brunham said his advice would be that if people choose to follow this diet, they should have their cholesterol monitored, and manage their cardiovascular risk factors.
“I wouldn’t say it is not appropriate to follow this diet based on this study,” he added. “This is just an observational study. It is not definitive. But if people do want to follow this dietary pattern because they feel there would be some benefits, then they should be aware of the potential risks and take steps to mitigate those risks.”
Jury still out
Dr. Nissen said in his view “the jury was still out” on this type of diet. “I’m open to the possibility that, particularly in the short run, a ‘keto-like’ diet may help some people lose weight and that’s a good thing. But I do not generally recommend this type of diet.”
Rather, he advises patients to follow a Mediterranean diet, which has been proven to reduce cardiovascular events in a randomized study, the PREDIMED trial.
“We can’t make decisions on what type of diet to recommend to patients based on observational studies like this where there is a lot of subtlety missing. But when studies like this are reported, the mass media seize on it. That’s not the way the public needs to be educated,” Dr. Nissen said.
“We refer to this type of study as hypothesis-generating. It raises a hypothesis. It doesn’t answer the question. It is worth looking at the question of whether a ketogenic-like diet is harmful. We don’t know at present, and I don’t think we know any more after this study,” he added.
The authors of the study reported no relevant financial relationships.
A version of this article originally appeared on Medscape.com.