‘100 per cent’ diet linked to ’12 per cent lower Alzheimer’s risk’

Switching to a diet praised by scientists could dramatically slash the risk of developing dementia, according to landmark new research. They insist it is never too late to make the change, as the advantages of a 100 per cent plant-based diet are evident even in those who alter their eating habits in their sixties.

However, the study, published in the journal Neurology, found that simply eliminating meat entirely is not sufficient, as an unhealthy plant-based diet is actually associated with a heightened risk of Alzheimer’s disease and other forms of dementia. The American research team found that participants whose diets deteriorated over a 10-year period faced a greater risk of dementia, while those who improved their diets experienced a reduced risk.

Researchers concluded that adopting a plant-based diet – even beyond the age of 60 – and steering clear of poor-quality plant-based food choices are both linked to a lower risk of all forms of dementia , reports the Mirror.

The team assessed three distinct types of plant-based diets:

• The overall plant-based diet involves consuming more plant foods than animal products such as meat, milk and eggs, without considering nutritional quality.
• The healthy plant-based diet focuses on nutritious plant foods including whole grains, fruits, vegetables, vegetable oils, nuts, legumes and tea and coffee.
• The unhealthy plant-based diet has fewer nutritious plant foods such as refined grains, fruit juices, potatoes and added sugars.

Vegetarian or vegan diets were not included as part of the research. Researchers warn that the study does not prove that consuming a higher quality plant-based diet directly causes a lower risk of dementia, merely highlighting an association between the two.

Study author Dr Song-Yi Park said: « Plant-based diets have been shown to be beneficial in reducing the risk of diseases like diabetes and high blood pressure, but less is known about the risk of Alzheimer’s disease and other dementias. Our study found that the quality of a plant-based diet mattered, with a higher quality diet associated with a reduced risk, and a lower quality diet associated with an increased risk. »

The research involved 92,849 participants with an average age of 59 at the start, including white, African American, Japanese American, Latino and Native Hawaiian individuals. Participants were tracked over an average span of 11 years, during which 21,478 developed Alzheimer’s disease or another related dementia.

At the study’s outset, all participants completed comprehensive food questionnaires. Researchers then evaluated how closely each individual’s diet aligned with an overall plant-based diet, a healthy plant-based diet, or an unhealthy plant-based diet, by analysing their intake of both nutritious and less nutritious plant foods, together with animal fats, meat, dairy, eggs, fish and seafood.

Each participant was subsequently assigned three separate scores indicating how closely they followed the three plant-based diet types, before being categorised into five distinct subgroups for each of the three diet scores.

How much dementia risk was lowered in those who ate the most plant foods

After adjusting for factors including age, physical activity and diabetes, the findings showed that when comparing individuals based on their overall plant-based diet score, those in the highest category who ate the most plant foods had a 12% lower risk of developing dementia compared to those in the lowest category.

When participants were evaluated on their healthy plant-based diet score, the highest category demonstrated a 7% lower risk compared to the lowest category. Meanwhile, when ranked by their unhealthy plant-based diet score, the highest category who consumed the most unhealthy plant foods faced a 6% higher risk of dementia than those in the lowest category.

Within a smaller cohort of 45,065 participants who reported their dietary habits again after 10 years, 8,360 subsequently developed dementia. Researchers also examined how dietary patterns evolved over time.

Compared to those whose eating habits remained stable, participants whose diets shifted most towards unhealthy choices had a 25% higher risk of dementia, while those who moved furthest away from an unhealthy diet had an 11% lower risk.

Dr Park, from the University of Hawaii, Honolulu, said: « We found that adopting a plant-based diet, even starting at an older age, and refraining from low-quality plant-based diets were associated with a lower risk of Alzheimer’s and other dementias.

« Our findings highlight that it is important not only to follow a plant-based diet, but also to ensure that the diet is of high quality. »