Forget the Mediterranean! The Japanese Diet is the new nutrition plan that could beat dementia, according to new research

Move over Mediterranean diet! A meal plan from a different region of the world is garnering a lot of buzz for its health benefits.

The Japanese diet – rich in fish, tea and soybeans – can protect the brain from shrinking and therefore may reduce the risk of dementia, according to a new study.

Researchers from Japan’s National Center for Geriatrics and Gerontology performed brain scans on two groups of Japanese people eating different diets.

One group ate a traditional Japanese diet while the other ate a Western diet, full of high fat foods like red meat, alcohol and pasta. 

Scans were performed twice over the course of two years, with the goal of determining how much brain tissue each group lost over time. 

They found that women in the Japanese diet group had, on average, lower levels of brain atrophy, or shrinkage, that is characteristic of dementia than the women who ate a Westernized diet. 

This finding comes after an increased focus on Japan’s lifestyle, since it was revealed to contain one of the world’s five ‘blue zones’– regions with lower rates of chronic disease and higher life expectancies than the rest of the world. 

Only 6.7 percent of people over 65 that live within the Okinawa prefecture of Japan develop dementia according to Dan Buettner, author of ‘The Blue Zones Solution’.

That’s close to half of the rate in the United states, which is around 11.3 percent. 

What sets blue zones apart from the rest of the world is the lifestyles that the people within them lead- which includes their diet. Other regions that were highlighted were in Greece, Costa Rica and Italy. 

‘Following a traditional Japanese diet may also be beneficial for brain health – and better for it than the typical western diet is,’ study authors Shu Zhang, a nutritional epidemiology researcher for Japan’s National Center for Geriatrics and Gerontology and Giovanni Sala, a psychology lecturer at the University of Liverpool wrote for the Conversation. It was posted in the Nutrition Journal in March. 

As a whole, Japan actually has a higher rate of dementia than the United States, despite the Okinawan bright spot. 

For instance, as of the last official measure in 2014, the national rate of dementia in people over 65 was 15 percent in Japan, and 11 percent in the US. 

This could have to do with the fact that Japan has the largest proportion of elderly people in the world- they represent about 29.1 percent of the country’s total population. In the US, elderly people comprise roughly 17.3 percent of the population.

The study authors defined a traditional Japanese diet as being based in fish, shellfish, rice, soybeans, green tea, citrus, pickles, mushrooms and seaweed. The western diet, by comparison, contained refined carbs like noodles, high fat-foods, soft drinks and alcohol. 

Generally, the Japanese diet is thought to be protective because its high in vitamins, polyphenols, phytochemicals and good fatty acids, all of which can help the body fight against inflammation. 

Staving off long term inflammation can help lubricate the brain, and keep its neurons working in the long run, the study authors wrote. 

In order to investigate those affects against other diets, the study examined at 1636 Japanese adults between age 40 to 89. The authors gave them a disposable camera to take pictures of their meals and asked them to keep a food diary documenting everything the ate and drank.

They also took down a genetic history, and noted other lifestyle factors, like smoking habits, physical activity and existing health conditions. This way, they could adjust the data to make sure whatever differences they observed at the end of the study were caused by diet changes, not other factors. 

Over the two year period, 589 participants followed a traditional Japanese diet, 697 participants ate a traditional western diet and 350 people ate a mainly plant based diet.  

The final, and most crucial, aspect to their study was taking regular brain scans, called MRI’s, of the participants. They were monitoring each participants brain tissue loss, known clinically as age-associated brain atrophy, because it’s a marker of dementia, the authors wrote. 

At the conclusion, the authors discovered that the women who followed a Japanese diet had significantly les brain shrinkage than the women who followed a western diet. There was no difference between the two group for men.

‘Interestingly, this effect was only apparent in women,’ Zhu wrote.

The authors provide two potential explanations for this effect. One, that the Japanese diet is full of magnesium and phytoestrogens, which have more of a protective effect on women than men. 

Phytoestrogens are compounds similar to the female sex hormone estrogen, found primarily in plants, and sometimes called plant estrogens. 

Previous research from the Institute for Aging and Alzheimer’s Disease Research supports this idea, saying that increasing intake of plant estrogens could help women fight of the cumulative effects of stress in the body. 

Two, the authors found that men were more likely to stray from the traditional Japanese diet than women. So they consumed more Western foods, like noodles and sake, which could mean that they would’ve seen less protective effects from the Japanese diet. 

Regardless, there are particular parts of the Japanese diet that they recommend incorporating, that are seen in other Blue Zone diets. These include upping your veggie and fish intake and cutting back on red meat, the authors wrote.

‘Embracing elements of the traditional Japanese diet and including foods such as fish, seafood, soy, miso, seaweed and shiitake mushrooms, may not only help improve cognitive function but overall health too,’ they said.