Eating red meat and processed meat hikes heart disease and death risk, study finds

Processed meats (stock image).

After a controversial study last fall recommending that it was not necessary for people to change their diet in terms of red meat and processed meat, a large, carefully analyzed new study links red and processed meat consumption with slightly higher risk of heart disease and death, according to a new study from Northwestern Medicine and Cornell University.

Eating two servings of red meat, processed meat or poultry -- but not fish -- per week was linked to a 3 to 7% higher risk of cardiovascular disease, the study found. Eating two servings of red meat or processed meat -- but not poultry or fish -- per week was associated with a 3% higher risk of all causes of death.

"It's a small difference, but it's worth trying to reduce red meat and processed meat like pepperoni, bologna and deli meats," said senior study author Norrina Allen, associate professor of preventive medicine at Northwestern University Feinberg School of Medicine. "Red meat consumption also is consistently linked to other health problems like cancer."

"Modifying intake of these animal protein foods may be an important strategy to help reduce the risk of cardiovascular disease and premature death at a population level," said lead study author Victor Zhong, assistant professor of nutritional sciences at Cornell, who did the research when he was a postdoctoral fellow in Allen's lab.

The paper will be published Feb. 3 in JAMA Internal Medicine.

The new findings come on the heels of a controversial meta-analysis published last November that recommended people not reduce the amount of red meat and processed meat they eat. "Everyone interpreted that it was OK to eat red meat, but I don't think that is what the science supports," Allen said.

"Our study shows the link to cardiovascular disease and mortality was robust," Zhong said.

What should we eat?

"Fish, seafood and plant-based sources of protein such as nuts and legumes, including beans and peas, are excellent alternatives to meat and are under-consumed in the U.S.," said study coauthor Linda Van Horn, professor of preventive medicine at Feinberg who also is a member of the 2020 U.S. Dietary Guidelines Advisory committee.

The study found a positive association between poultry intake and cardiovascular disease, but the evidence so far isn't sufficient to make a clear recommendation about poultry intake, Zhong said. Still, fried chicken is not recommended.

The new study pooled together a large diverse sample from six cohorts, included long follow-up data up to three decades, harmonized diet data to reduce heterogeneity, adjusted a comprehensive set of confounders and conducted multiple sensitivity analyses. The study included 29,682 participants (mean age of 53.7 years at baseline, 44.4% men and 30.7% non-white). Diet data were self-reported by participants, who were asked a long list of what they ate for the previous year or month.

Key findings:

• A 3 to 7% higher risk of cardiovascular disease and premature death for people who ate red meat and processed meat two servings a week.
• A 4% higher risk of cardiovascular disease for people who ate two servings per week of poultry, but the evidence so far is not sufficient to make a clear recommendation about poultry intake. And the relationship may be related to the method of cooking the chicken and consumption of the skin rather than the chicken meat itself.
• No association between eating fish and cardiovascular disease or mortality.

Limitations of the study are participants' dietary intake was assessed once, and dietary behaviors may have changed over time. In addition, cooking methods were not considered. Fried chicken, especially deep fat-fried sources that contribute trans-fatty acids, and fried fish intake have been positively linked to chronic diseases, Zhong said.

Other Northwestern authors are Dr. Philip Greenland, Dr. Mercedes R. Carnethon, Dr. Hongyan Ning, Dr. John T. Wilkins and Dr. Donald M. Lloyd-Jones.

The study was funded by National Institutes of Health/National Heart, Lung, and Blood Institute (R21 HL085375), American Heart Association Strategically Focused Research Networks and the Feinberg School of Medicine.

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Materials provided by Northwestern University. Original written by Marla Paul. Note: Content may be edited for style and length.

Researchers reconstruct spoken words as processed in nonhuman primate brains

Rhesus macaque

A team of Brown University researchers has used a brain-computer interface to reconstruct English words from neural signals recorded in the brains of nonhuman primates. The research, published in the journal Nature Communications Biology, could be a step toward developing brain implants that may help people with hearing loss, the researchers say.

"What we've done is to record the complex patterns of neural excitation in the secondary auditory cortex associated with primates' hearing specific words," said Arto Nurmikko, a professor in Brown's School of Engineering, a research associate in Brown's Carney Institute for Brain Science and senior author of the study. "We then use that neural data to reconstruct the sound of those words with high fidelity.

"The overarching goal is to better understand how sound is processed in the primate brain," Nurmikko added, "which could ultimately lead to new types of neural prosthetics."

The brain systems involved in the initial processing of sound are similar in humans and non-human primates. The first level of processing, which happens in what's called the primary auditory cortex, sorts sounds according to attributes like pitch or tone. The signal then moves to the secondary auditory cortex, where it's processed further. When someone is listening to spoken words, for example, this is where the sounds are classified by phonemes -- the simplest features that enable us to distinguish one word from another. After that, the information is sent to other parts of the brain for the processing that enables human comprehension of speech.

But because that early-stage processing of sound is similar in humans and non-human primates, learning how primates process the words they hear is useful, even though they likely don't understand what those words mean.

For the study, two pea-sized implants with 96-channel microelectrode arrays recorded the activity of neurons while rhesus macaques listened to recordings of individual English words and macaque calls. In this case, the macaques heard fairly simple one- or two-syllable words -- "tree," "good," "north," "cricket" and "program."

The researchers processed the neural recordings using computer algorithms specifically developed to recognize neural patterns associated with particular words. From there, the neural data could be translated back into computer-generated speech. Finally, the team used several metrics to evaluate how closely the reconstructed speech matched the original spoken word that the macaque heard. The research showed the recorded neural data produced high-fidelity reconstructions that were clear to a human listener.

The use of multielectrode arrays to record such complex auditory information was a first, the researchers say.

"Previously, work had gathered data from the secondary auditory cortex with single electrodes, but as far as we know this is the first multielectrode recording from this part of the brain," Nurmikko said. "Essentially we have nearly 200 microscopic listening posts that can give us the richness and higher resolution of data which is required."

One of the goals of the study, for which doctoral student Jihun Lee led the experiments, was to test whether any particular decoding model algorithm performed better than others. The research, in collaboration with Wilson Truccolo, a computational neuroscience expert, showed that recurrent neural networks (RNNs) -- a type of machine learning algorithm often used in computerized language translation -- produced the highest-fidelity reconstructions. The RNNs substantially outperformed more traditional algorithms that have been shown to be effective in decoding neural data from other parts of the brain.

Christopher Heelan, a research associate at Brown and co-lead author of the study, thinks the success of the RNNs comes from their flexibility, which is important in decoding complex auditory information.

"More traditional algorithms used for neural decoding make strong assumptions about how the brain encodes information, and that limits the ability of those algorithms to model the neural data," said Heelan, who developed the computational toolkit for the study. "Neural networks make weaker assumptions and have more parameters allowing them to learn complicated relationships between the neural data and the experimental task."

Ultimately, the researchers hope, this kind of research could aid in developing neural implants the may aid in restoring peoples' hearing.

"The aspirational scenario is that we develop systems that bypass much of the auditory apparatus and go directly into the brain," Nurmikko said. "The same microelectrodes we used to record neural activity in this study may one day be used to deliver small amounts of electrical current in patterns that give people the perception of having heard specific sounds."

The research was supported by the U.S. Defense Advanced Research Projects Agency (N66001-17-C-4013) and a private gift to Brown.

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Materials provided by Brown University. Note: Content may be edited for style and length.