Does eating meat increase dementia risk?

Studies have shown that a brain-healthy diet consists of high levels of fruits, vegetables, fish, and legumes. But what about meat intake? A recent observational study reported that people who consumed large amounts of processed meat had an elevated risk of dementia, including Alzheimer’s disease [1].

Findings come from the UK Biobank, a large cohort study of 493,888 participants who were 40-69 years old with no dementias at the start of the study. Participants answered detailed questionnaires on their dietary intakes at the beginning of the study, then every 3-4 months for four additional times. Categories of meat in the diet questionnaires included processed meat (e.g., bacon, ham, sausages, meat pies, kebabs, burgers, chicken nuggets), unprocessed beef, unprocessed poultry, unprocessed lamb/mutton, and unprocessed pork. These participants were followed for an average of eight years, at which point there were 2,896 participants with dementia, of whom 1,006 had Alzheimer’s disease. Those who were diagnosed with dementia during the follow-up were more likely to be older, a smoker, less educated, less physically active, less economically secure, and have a family history of dementia.

In terms of meat intake, each additional 25 grams (approximately a single serving) of processed meat per day was associated with a 44% increased risk for all dementias and a 52% increased risk for Alzheimer’s disease. In contrast, intake of each additional 50 grams of unprocessed red meat (total intake of unprocessed beef, lamb, and pork) per day was associated with a 19% lower risk of all dementias and a 30% lower risk for Alzheimer’s disease, after controlling for many factors such as age, socioeconomic status, educational level, body mass index, physical activity level, smoking status, stroke history, family history of dementia, and dietary patterns. These same associations between meat intake and dementia risk were also observed in people with APOE4, the genetic risk factor for Alzheimer’s disease.

Why is there a difference between processed meat and unprocessed meat? Processed meat contains preservatives that are not present in fresh meat, such as nitrite which can turn into harmful compounds, increasing oxidative stress and inflammation [2]. Also, processed meat is often high in sodium levels, which could lead to high blood pressure, a risk factor for dementia [3].

While this was a large study with almost a half a million people, it was an observational study and not a randomized controlled clinical trial. Therefore, this study could identify associations, but it was not designed to prove cause and effect. In other words, this study does not prove that eating large amounts of processed meats directly increases dementia risk, or that eating more unprocessed meats could protect against dementia. Further research is needed as findings from this study is not entirely consistent with previous studies, some of which showing a lack of association between meat intake and dementia risk [4; 5], or an increased risk for dementia associated with low meat intake (once weekly or less) compared with regular meat intake (4+ times per week) [6]. But based on available research, a healthy diet rich in fruits, vegetables, legumes, fish, and nuts and low in processed foods appears to be most beneficial for brain health.

1. Zhang H, Greenwood DC, Risch HA et al. (2021) Meat consumption and risk of incident dementia: cohort study of 493,888 UK Biobank participants. The American journal of clinical nutrition.
2. Turesky RJ (2018) Mechanistic Evidence for Red Meat and Processed Meat Intake and Cancer Risk: A Follow-up on the International Agency for Research on Cancer Evaluation of 2015. Chimia  72, 718-724.
3. Abell JG, Kivimaki M, Dugravot A et al. (2018) Association between systolic blood pressure and dementia in the Whitehall II cohort study: role of age, duration, and threshold used to define hypertension. European heart journal  39, 3119-3125.
4. Barberger-Gateau P, Letenneur L, Deschamps V et al. (2002) Fish, meat, and risk of dementia: cohort study. Bmj  325, 932-933
5. Fischer K, Melo van Lent D, Wolfsgruber S et al. (2018) Prospective Associations between Single Foods, Alzheimer's Dementia and Memory Decline in the Elderly. Nutrients  10.
6. Ngabirano L, Samieri C, Feart C et al. (2019) Intake of Meat, Fish, Fruits, and Vegetables and Long-Term Risk of Dementia and Alzheimer's Disease. Journal of Alzheimer's disease : JAD  68, 711-722.

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