December 6, 2018
Credit: Sony Salzman
In Hollywood, ultra-low-carb diet fads come and go. A trendy new diet called the ketogenic diet, or "keto" for short, has been embraced as a weight-loss strategy by superstars like Kim Kardashian and Melissa McCarthy. But now, new scientific evidence suggests that the celebrity-backed diet may have significant cognitive benefits for older people living with HIV.
Keto involves cutting out carbs and instead eating almost entirely protein and fat. This diet triggers the body to start burning ketone bodies instead of carbohydrates as fuel -- and scientists think this alternative metabolism process may somehow impact the body's inflammatory response.
The keto diet has been used for years as a treatment for certain types of epilepsy and is now being studied in other diseases that involve inflammation, such as diabetes, cancer, and Alzheimer's disease.
New research presented at the Association of Nurses in AIDS Care (ANAC) conference in Denver suggests that the keto diet may be beneficial for older people living with HIV who experience cognitive decline. This research is supported by similar findings among older adults without HIV.
Though it's not exactly clear why older people living with HIV are likely to experience more severe cognitive impairment compared to HIV-negative people, researchers think it might have something to do with the body's inflammatory response to the infection.
The team includes Shannon Morrison, Ph.D., CRNP, Pariya Fazeli, Ph.D., Barbra Gower, Ph.D., Amanda Willig, Ph.D., RDN, Jarred Younger, Ph.D., N. Markie Sneed, M.S.N., CRNP, and David Vance, Ph.D. -- based at University of Alabama at Birmingham's School of Nursing.
They evaluated the keto diet's effect by studying 14 HIV-positive older adults with cognitive impairment, splitting them into two groups. The first group ate a normal diet, and the second ate a combination of high-fat proteins and nuts, plus low-carb veggies.
After 12 weeks, the keto group saw a significant improvement in executive function, meaning they scored better on tests meant to evaluate memory, processing speed, and ability to switch tasks quickly. They also scored better on other cognitive measures, like attention span and spatial recognition.
In particular, the seven patients on keto scored significantly better on two tests designed to measure improvement in dementia patients, called "Trials A" and "Trials B."
The Trials A test evaluates psychomotor speed, visuospatial tracking, and attention. At baseline, the keto group scored an average of 41.6 points, and after 12 weeks, their average score jumped to 44.6 points. The control group, meanwhile, declined from an average of 50 points at baseline to 48.3 points 12 weeks later.
Trials B is a test that evaluates executive function, task switching, and working memory. The keto group had an average score of 39.7 at baseline and jumped to 49.7 after 12 weeks, while the control group declined from 48.4 to 44.7.
However, these positive effects wore off quickly when patients resumed their normal diet after week 12, with cognitive scores averaging out again after 18 weeks.
All of the participants in the study were taking antiretrovirals -- and, interestingly, there were no differences between the two groups in terms of body composition, lipid count, or metabolic measures throughout the study.
The researchers concluded that the ketogenic diet might offer a non-pharmacological approach to treating cognitive decline in older adults with HIV, which could in turn help ease pill burden for older people who are already taking several medications.
Still, there are caveats to the ketogenic diet. The first caveat is that the diet is extremely difficult to follow long-term, requiring a food intake comprised of 75% fat, 20% protein, and only 5% carbs. The average American gets about half of their daily food from carbs.
Second, and most importantly, more studies are still needed to understand how the diet influences inflammation and other important health metrics. While promising, the recently presented ANAC study is one of about two dozen studies that evaluate the diet's effect in a small handful of patients.
We'll have to wait for larger studies to determine whether the benefits outweigh the risks for people living with HIV. Until then, most doctors are still recommending a balanced diet full of fruits and vegetables -- and yes, carbohydrates.
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