Higher-Quality Plant-Based Diet Linked to Lower Dementia Risk, Study Finds

A higher-quality plant-based diet may help reduce the risk of Alzheimer’s disease and other forms of dementia, according to new research published in Neurology, the journal of the American Academy of Neurology.

The large-scale observational study suggests that not all plant-based diets offer the same benefits, with healthier choices linked to better cognitive outcomes in later life—an important consideration for care providers supporting older residents.

Researchers examined three types of plant-based eating patterns:

• Overall plant-based diet – emphasising plant foods over animal products, regardless of quality
• Healthful plant-based diet – focusing on nutrient-rich foods such as whole grains, fruit, vegetables, nuts, legumes, and plant oils
• Unhealthful plant-based diet – including more refined grains, sugary foods, fruit juices and heavily processed options

The findings indicate that simply increasing plant-based foods is not enough; the quality of those foods plays a crucial role.

Lead researcher Song-Yi Park explained that while plant-based diets are already known to reduce the risk of conditions such as diabetes and high blood pressure, their impact on dementia risk has been less clear.

The study followed 92,849 adults with an average age of 59 over approximately 11 years. Participants came from a range of ethnic backgrounds and completed detailed dietary questionnaires at the outset.

Over the course of the study, more than 21,000 participants developed Alzheimer’s disease or another form of dementia.

After accounting for factors such as age, physical activity and existing health conditions, researchers found:

• Those with the highest intake of plant-based foods overall had a 12% lower risk of dementia compared to those with the lowest intake
• Participants following the healthiest plant-based diets had a 7% lower risk
• Those consuming the most unhealthy plant-based foods had a 6% higher risk

In a subgroup of more than 45,000 participants who provided follow-up dietary data after 10 years, changes in eating habits were also linked to dementia outcomes.
• Individuals whose diets shifted most towards unhealthy plant-based foods had a 25% higher risk of developing dementia
• Those who moved away from poorer-quality diets saw an 11% reduction in risk

Implications for Care Settings

The findings may be particularly relevant for residential and nursing care providers, where nutrition plays a key role in supporting long-term health and wellbeing.
Researchers concluded that adopting a plant-based diet—even later in life—may be beneficial, but stressed that nutritional quality is critical.

For care homes, this reinforces the importance of offering balanced menus rich in whole, minimally processed plant foods, while limiting refined and high-sugar options.

As dementia rates continue to rise across the UK, the study adds to growing evidence that dietary choices could be a modifiable factor in reducing risk and supporting healthier ageing.