'I'm a GP - my 33p afternoon snack can help you live longer and reduce your dementia risk'

The expert stated: "At this time of the year we’re often thinking about what things in our lives need to change. It tends to be a time of scarcity where we stop drinking and cut down on calories, but often we’re not thinking about the long-term.

"Fortunately, there are some simple and delicious foods that improve longevity and can actually reduce your risk of dementia. The added bonus is they're generally good for your waistline too."

Emphasising the importance of omega-3 fatty acids, she recommended stocking up on oily fish, nuts and seeds.

For a longevity boost and reduced risk of dementia, Dr Merrifield reaches for a handful of nuts as an afternoon snack, costing her less than 40p per day.

Omega-3 fatty acids

The expert stated: "Dietary intake of omega-3 fatty acids reduces the risk of heart disease, diabetes, depression and cancer.

"They can also improve blood flow in the brain and cognitive function."

Referencing an article published in the National Library of Medicine on the relationship between omega-3 fatty acids and cognitive decline, she said: "There is emerging evidence that eating omega-3 fatty acids can reduce the risk of developing dementia or cognitive decline by up to 20 per cent."

Oily fish

If you want to increase your intake of omega-3 fatty acids, one of the "best sources" is fish like mackerel, salmon, anchovy and tuna.

Dr Merrifield said: "The recommended intake is around two portions of oily fish a week. In general, if you're not eating around two portions of oily fish a week, I'd recommend you consider omega-3 supplements."

Nuts and seeds

For non-fish eaters, nuts and seeds are also a good source of omega-3s - not to mention versatile.

Dr Merrifield said: "These can be eaten as a snack or sprinkled onto your breakfast cereal or a bowl of yoghurt. Chia seeds, flaxseed and walnuts are some of the best options here."

The benefits of eating nuts are wide-reaching. The expert explained: "In addition to omega-3 fatty acids, nuts have a whole host of bioactive compounds such as vitamins, minerals and antioxidants."

She referenced an article published in BMC Medicine on nut consumption and the risk of cardiovascular disease, total cancer, all-cause and cause-specific mortality.

It read: "Higher nut intake is associated with reduced risk of cardiovascular disease, total cancer and all-cause mortality, and mortality from respiratory disease, diabetes, and infections."

The GP concluded: "I keep a jar of mixed nuts on my kitchen counter and a handful of nuts is my go-to afternoon snack."

Tesco Mixed Nuts 200g costs £2.65. The supermarket recommended a daily serving of 25 grams, which amounts to around 33p. Prices may vary at other supermarkets.

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Best foods for longevity and reducing your risk of dementia

1. Omega-3 fatty acids
2. Oily fish
3. Nuts and seeds
4. Polyphenols
5. Fruits and vegetables
6. Legumes
7. Whole grains

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