Key Takeaways

• We found 22 studies reporting a connection between beef intake and cognition, most of which looked at red meat.
• Intervention studies were mostly conducted on children from Africa and Europe, and assessed school-related abilities.
• Observational studies were largely conducted on adult and senior populations in Asia, Europe and North America, and assessed cognitive decline, intelligence, memory and related abilities.
• The majority of observational studies reported beef and red meat intakes far below their respective regional averages.
• Most studies were not primarily designed to measure beef and cognitive outcomes, resulting in high or serious risk of bias.

Conclusion (TLDR)

Given the low quality of data and high heterogeneity of available studies, it’s too early to tell if beef impacts cognition. See for yourself using the interactive visualization below.

 

Our systematic review

We evaluated evidence from 22 studies from 2003 to 2021, including nine trials and 13 observational studies on beef or red meat intake and cognitive outcomes. We included studies that were performed on humans of all ages and health status (excluding those with brain injury, neurodegenerative disease, or considerable cognitive deficits beyond mild impairment), reported and quantified red meat or beef intake, and measured respective cognitive outcomes. After extracting the data on dietary variables and cognitive domains, we assessed risk of bias using the RoB 2.0 tool for trials and the RoB-NoBs tool for observational studies. Study details can be further explored under the “Publications Trends” tab in the visualization tool.

Our findings

• • We need to be more specific about how beef is consumed.

The terminology and exposures among the studies varied considerably and were classified into three categories: (1) beef only, (2) red meat (including beef), and (3) red meat (unspecified). Forms of beef, if specified, included a variety of cuts (e.g., eye round roast, top sirloin, short loin) along with minced, ground, and dried beef powder. Furthermore, some studies included pork, lamb, chicken and processed meats under the category of “red meat”. Cooking methods (roasting, grilling, stewing) were largely omitted and only three studies specified the meat’s fat content (10-12% fat, “lean,” and 90% lean). As we know, a food’s nutritional profile and food matrix can influence its physiological effects and subsequent health outcomes. Therefore, the heterogeneity among beef and red meat exposures remains a significant limitation in understanding its impact on cognition.

• • Different study populations make generalizations challenging.

Study designs included children (3-11 years), adults (18-64 years) and seniors (65+ years) from all over the world. Trials were conducted primarily on children with the majority of the studies occurring in Africa. Observational studies were focused on adults and seniors with the majority of the studies taking place in Asia. There were no studies on adolescents or on populations in South America or Oceania.

Furthermore, several observational studies included participants with mild cognitive impairments or risk of cognitive impairment, which raises concerns over the accuracy of the dietary recalls and food frequency questionnaires. This design limitation quickly becomes a chicken-and-egg issue when it comes to exploring beef intake and risk of cognitive impairment. Do participants recall eating more/less meat, or do they actually have a different diet?

• • Large discrepancies in beef intake raise questions.

The prescribed beef and red meat intake in intervention studies ranged from about 28 to 85 grams per day. The proximity of intake to regional averages also varied, with some studies exposing participants to intakes much higher than their national averages, some much lower and only one studied evaluated meat at a regionally representative intake level. Furthermore, many trials failed to account for red meat intake outside of the prescribed intervention, likely underestimating the estimates of total beef intake.

Beef and red meat intake from the observational studies ranged from about 0.5 to 153 grams per day. Beyond the variability in both red meat intake as well as precision, all the studies reported intakes below respective country averages, particularly in China. This may in part be explained by the inclusion of poultry in national average estimates as well as the age of these populations (mainly adults and seniors). Therefore, either the study data is more reliable than national averages or the food frequency questionnaires are inaccurate due to participants underestimating red meat intake.

Details on intakes relative to regional averages are displayed on the “How much beef was consumed?” tab of the visualization tool.

• • Moving beyond basic cognitive tests is necessary.

For cognitive outcomes, there was a wide range of domains assessed (memory, executive function, language and verbal function, etc.), measurement tools utilized (MMSE, MoCA, etc.), and respective interpretations. Assessment tools were classified into two categories: Domain-specific and Global. Domain-specific tools offer more in-depth evaluations of targeted sub-domains or tasks while global tools offer a more broad and wide-range assessment of cognitive abilities (read more on this topic in our post here). Both tools have their own benefits and limitations, however it’s important to recognize the value of domain-specific tools for measuring explicit cognitive tasks to more accurately assess improvements or decline. In this review, many of the studies evaluating language and verbal function and all the studies measuring numeric cognition utilized global tools, thereby undermining the quality of the respective interpretations.

Using the visualization tool, under the study outcome tabs, you can see that most observational studies used global tools whereas the intervention studies used both global and domain-specific tools. These inconsistencies among the cognitive tools make it difficult to draw accurate conclusions on the effects of beef and red meat intake.

• • Future studies will need to improve their design to reduce the risk of bias.

Lastly, the available evidence on beef and cognition is limited by risk of bias. The visualization tool provides a color-coded risk category to each studying using either the RoB-NoBs (observational studies) or the RoB 2.0 (trial studies) assessment tools. Over half of the intervention trials were rated with high risk and over three quarters of the observational studies were rated with critical or serious risk of bias. Future trials can reduce this risk by implementing blinding procedures to the randomization process and providing a pre-analysis plan. Observational studies can improve by adjusting for confounding factors, clearly defining the exposure (beef type, cut, fat %, grade, etc.), and pre-registering study protocols.

Brain health is an emerging priority in functional foods.

This review is timely for both consumer and public health interests. While the impact of nutrition on cognition is nothing new, there’s a growing awareness and interest among consumers on the role of food in supporting brain health. In fact, the 2023 IFIC Health & Wellness report found that a quarter of adults surveyed sought “brain function” benefits from their diet. For parents, this may mean incorporating brain-boosting foods that could give their child an edge. For older adults, this may mean prioritizing nutrition to stay sharp, preserve memory and fight cognitive decline. Motivation may vary by life stage, but this pursuit of functional foods for brain health will likely continue to grow, especially with an aging population worldwide.

So, what’s next?

Our systematic review highlights the limitations of the evidence on beef intake and cognition, however it also identifies gaps for future research and provides recommendations to bring significant progress to this field. The visualization tool offers a unique way to review and interact with the data, explore the results and share findings. Research on nutrition for brain health will continue to be relevant from a public health and consumer perspective. Therein lies an exciting opportunity for researchers to explore and improve our understanding of beef as it relates to cognition.

Looking for a similar analysis or deep dive? Our team can support you with your research question, whether through a discovery phase or a more structured review.

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