Why Mediterranean diet is good for you - it's all in the gut

Switching in old age from a bland, unvaried diet to a Mediterranean mix of fresh vegetables, fruit and fish restores a balance of intestinal bacteria linked to good health, researchers say.

In a clinical trial with 612 volunteers aged 65 to 79 across five European countries, those who adopted a typical Mediterranean diet for a year showed more "good" microbes linked to better brain function, and a net drop in gut flora thought to trigger inflammation and increased frailty.

The results held true regardless of age or weight, both of which influence the community of bacteria species - numbering up to 1,000 - that make up the human microbiome, the scientists reported in the journal Gut.

"This diet might act on gut bacteria in such a way as to help curb the advance of physical frailty and cognitive decline in older age," said lead author Paul O'Toole, head of the School of Microbiology at University College Cork in Ireland.

In the later stages of life there is a natural decline of bodily functions and a tendency for the immune system to overreact, leading to a clinical condition known as frailty.

"In an older person, the immune system is striking at shadows," O'Toole explained.

"It is constantly turned on and firing into deep space."

Cognitive function - especially short-term memory - also "goes downhill as we get older", he added.

Previous research has suggested that the restricted diet common among older people, especially those living alone or in institutions, sharply reduces the range and types of bacteria found in the gut, which helps to speed the onset of these conditions.

"At the same time, we have long known the Mediterranean diet" - rich in fresh produce and olive oil, and fish rather than red meat - "is good for you," O'Toole noted.

This style of cuisine correlates with less frailty and inflammation, and better cognitive function, he added. But researchers did not know why.

O'Toole and his colleagues were part of a European project that set up an experiment to see if gut microbes might play a role.

Coordinating with teams in Poland, Italy, France and the Netherlands, they compared elderly subjects eating a narrow range of mostly prepared foods with those who had switched to eating fresh, Mediterranean diet ingredients delivered to their doorstep every week.

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In the second group, the good diet helped good bacteria flourish, while microbes associated with poor health were reduced in number.

But the strongest evidence of the Mediterranean diet's impact came in looking at who adhered to the new regimen most closely.

"We interviewed everyone in detail to measure compliance," O'Toole said.

A year was long enough to see a measurable change in mix of microbes, but elderly people would have to stick to the diet far longer to see "clinically significant" changes in inflammation and frailty scores, the study found.

"I would recommend this diet to anyone in that age group, but at the same time I'm realistic," he said.

"My priority is to find a supplements that contains all the ingredients of a Mediterranean diet to replace the missing microbes in frail and older people."

It is never too soon to start eating more healthily, either.

"If you have been on a bad diet for a really long time … it's like the World Wildlife Fund says: 'extinction is forever', and it may not be possible to bring the microbes back even with a good diet."

Start your Mediterranean diet now with these recipes:

FALAFEL

Most people make falafel from a ready-mix packet - just stir in water, shape and fry. But fresh falafel, made from scratch, can be a revelation. It's lighter and has more texture and flavour than the instant variety.

With the following recipe, you may not need to add flour if your food processor is able to grind the chickpeas finely.

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I like to form the falafel mixture into the shape of small (3-4cm long) rugby balls.

This allows them to be crunchy outside but moist inside. Flat patties are very crunchy and fit best into pita bread but they can be dry, while round balls can be difficult to cook through.

Serve the falafel with tahini (from a jar; stir in enough warm water to thin it out), harissa (chilli paste; in the supermarket it is usually in the section that has couscous), sliced tomatoes, cabbage or lettuce and onions, and with dishes of hummus, tzatziki and grilled aubergine.

200 grams dried chickpeas
2-3 large garlic cloves
1/2 tsp cumin seeds
3-4 spring onions, chopped
15 grams fresh parsley
15 grams fresh coriander
1 tsp fine sea salt, or to taste
1/4 tsp ground cayenne
3/4 tsp baking powder
About 30 grams plain flour, breadcrumbs or matzoh meal
Oil, for frying

1. Soak the chickpeas overnight in plenty of water. Drain them and grind in a food processor.
2. Toast the cumin seeds and crush them in a mortar.
3. Add the cumin, garlic cloves, spring onions, parsley, coriander, salt, cayenne and baking powder to the chickpeas and process until finely ground but not completely smooth; there should be some texture.
4. Transfer to a bowl and mix thoroughly, taste and adjust seasonings if necessary.
5. Squeeze some of the mixture in your hand - if it's too crumbly, add flour, breadcrumbs or matzoh meal until it binds.
6. Shape the mixture into rugby-ball shapes (or patties or spheres, if you prefer) - you should get about 30.
7. Place them on a plastic wrap-lined baking tray.
8. Pour cooking oil into a skillet to a depth of about 1.5cm.
9. Heat the oil to 180 degrees Celsius. To test the temperature, drop a little of the falafel mixture into the oil - it should sizzle vigorously and turn pale golden in 10 seconds.
10. Start frying the balls - cook them in batches and don't crowd the pan.
11. Cook for about three minutes in total so they're medium brown on the outside but still moist within.
12. Drain on paper towels. Guests can stuff the falafel into warm pita bread with tzatziki, hummus, vegetables and other condiments.

TZATZIKI

If you use a large, watery cucumber, peel it, cut it in half, scoop out and discard the seeds and use only the flesh.
200 grams whole-milk plain yogurt, preferably Greek-style
200 grams cucumbers, preferably the slim Chinese or Japanese variety
2-4 garlic cloves

Dice the cucumber and mince the garlic. Mix the ingredients together and refrigerate until ready to use.

HUMMUS

Soaking the chickpeas not only reduces the cooking time, but helps them cook more evenly.

200 grams dried chickpeas
4 garlic cloves, divided, or to taste
50 grams tahini, or to taste
50ml fresh lemon juice, or to taste
30ml extra-virgin olive oil
Fine sea salt, to taste
To serve: paprika and extra-virgin olive oil

1. Soak the chickpeas for several hours or overnight.
2. Drain them, put them in a saucepan and add enough fresh water to cover by about 3cm. Add two peeled garlic cloves and bring to the boil. Lower the heat, cover the pot partially with the lid and simmer until the chickpeas are tender.
3. Discarding the garlic, use a slotted spoon to scoop the chickpeas into the bowl of a food processor.
4. Add two fresh garlic cloves and a ladleful of the cooking water and process to a rough paste.
5. Add the tahini, lemon juice and salt - and more cooking water if necessary - then process until smooth.
6. While the food processor is running, add the olive oil. Taste for seasonings and add more garlic, tahini, lemon juice and salt if necessary.
7. If the mixture is too thick, add more cooking water.
8. Transfer to a bowl, sprinkle with paprika and drizzle with olive oil.

ALSO READ: Mediterranean diet may be good for leg arteries, too

GRILLED AUBERGINE

The cooks at L'As du Fallafel use large, Italian aubergines but in Hong Kong, Chinese and Japanese aubergines are cheaper and much easier to find.

You can cook the aubergine under a gas grill, on a barbecue or on the stove using a ridged grill-pan.

2-3 thick Chinese or Japanese aubergines
Oil, for brushing

1. Slice the aubergines on the diagonal about 5mm thick.
2. Brush with oil and cook on a medium-high heat, turning the slices to give them the classic criss-cross grill marks.
3. If necessary, brush with more oil to stop them from sticking to the pan. Cook until tender.