Blue Zones: How Much Does Food Affect Life Expectancy?

Over the last couple of centuries, world life expectancy has doubled. In the quest to live a long and healthy life, to what extent do our diets really play a role?

What are Blue Zones?

Blue Zones are regions of the world where people are reported to live longer than average. As of today, there are five well-known blue zones in the world: Okinawa Prefecture in Japan; Nuoro Province, Sardinia, Italy; Nicoya Peninsula in Costa Rica; Icaria in Greece, and Loma Linda in California.¹

The idea of the Blue Zone has captivated the public imagination since the Netflix docuseries Live to 100: Secrets of the Blue Zones, but it’s an idea that’s been around for a long time. It was coined in 2000 but first appeared in an academic paper by longevity researchers Dr Michel Poulain and Dr Giovanni Pes in 2004. A study by the pair identified Nuoro province of Sardinia as the place in the world with the most men over 100 years old and labelled the area a Blue Zone.²

But what does this term really mean, and can the research behind Blue Zones help the average person live longer?

Can we trust the Blue Zone label?

The idea of a secret to longevity might appeal to the masses, but even the researchers behind the term Blue Zone advise caution. “There is something of a myth around the term because some people think it hides the secret to eternal youth”, co-author of the 2004 study, Dr Poulain, told FoodUnfolded.

Another problem is that verifying the ages of some of the world's longest-lived is almost impossible. This is because verifiable records rarely exist, forcing scientists to rely on the memory of the local community, which is often inexact.³

This has led to controversies over whether certain areas are genuine Blue Zones and has made it difficult to identify new ones.

“I travelled to Cuba three times, and each time, I visited an area with lots of centenarians, where I expected to find a Blue Zone,” Dr Poulain said. “But getting the administrative data, such as birth certificates, was impossible. I was in one municipality for five minutes before the police came to throw me out. Without the data, I could not confidently identify a new Blue Zone.”

Already established Blue Zones are also under scrutiny. Over 20 years ago, Okinawa Province was considered an area of exceptional longevity, but a more recent study showed that men in the area do not live as long as men in other regions of Japan.^{4, 17} The more recent study stated that current data suggests that “the remarkable Okinawan longevity is now a phenomenon of the past” due to the Westernisation of diet and the spread of cardiovascular diseases.⁴

Questions have also been raised about whether affluent areas, such as Loma Linda, California, are inherently more likely to be Blue Zones. Wealth is the biggest socioeconomic advantage to longevity, meaning richer people tend to live longer, but this isn’t exactly a secret to living long.⁵

Irrespective of the questions around the term, do the five “Blue Zones” hold clues on how we can engineer our diet to help us live longer?

Masa Narita, a centenarian, gets her hair set by a hairdresser at a beauty salon near her house in Osaka, Japan. "Taking things easy is the key to longevity," Narita said. According to the Japanese Ministry of Health, Labor and Welfare nearly 90 percent of centenarians in Japan are women. Photo by Yuriko Nakao via Getty Images.

The Blue Zone diet

Most Blue Zones have a predominantly plant-based diet rich in fruit, vegetables, nuts, beans, grains and pulses, as well as moderate amounts of seafood and small quantities of dairy and red meat.⁶ This framework follows much of the conventional advice for a healthy diet - whole foods over processed foods, red meat and dairy in moderation, and plenty of fruit, vegetables, grains and pulses.⁷

Even if the theory behind “Blue Zones” is controversial, it’s no secret that healthy diets matter greatly. Poor diets kill more people globally every year than smoking, high blood pressure, or any other health risk.⁸ At the same time, there are variations in diet among the Blue Zones, so we can’t confidently say that “if you want to live until you’re 100, just eat like they do in Sardinia”.

For example, the average diet in Okinawa, Japan, is low in calories, based largely on root vegetables, including purple sweet potato, and contains fish and lean meat.⁶

“The diet also includes a modest intake of Westernised products, such as lean meat, milk and other dairy products,” Dr Shoichiro Tsugane, Director of the National Institutes of Biomedical Innovation, Health and Nutrition, told FoodUnfolded. “Many of the non-alcoholic beverages people in Japan drink on a daily basis are sugar-free beverages such as green tea.”

By comparison, the average diet in Loma Linda, California, is predominantly vegan and rich in leafy greens, nuts and legumes.⁶ It’s therefore difficult to pinpoint a single ideal diet for longevity - raising valid questions about whether certain foods will really help us live longer than others.

How much does food affect life expectancy?

Unfortunately, science doesn’t yet have precise answers to questions like this one, Dr Daniel Belsky, Associate Professor of Epidemiology at Columbia University Mailman School of Public Health, told FoodUnfolded.

“But what we eat certainly affects how we age and our chances of living a long, healthy life.”

For example, eating a diet of whole foods rich in nutrients may increase the chance of living a long life more than a diet that frequently includes ultra processed or fast foods might.

A recent study found that a healthy diet can increase lifespan. People who consistently eat healthily had a 9-14% lower risk of death from any cause than people with poor diets.⁹ The study also found that people can increase their life expectancy by altering their diet at any age - people who improved their diet over the more than two-decade-long experiment were significantly associated with an eight per cent reduction in mortality during the study period.^9, 19

The study suggested that the Mediterranean diet is “optimal” for all people, but other studies have shown that no one diet is perfect for everyone owing to individual differences in gut microbes, lifestyle, genes and environment.^{10, 11} Even identical twins process food differently, likely due to the difference in gut microbes, and this means that one set of diet advice isn’t perfect for everyone.¹¹

The study’s author, Tim Spector, told CNBC that each person should work out what diet works best for them based on “trial and error”.¹² An argument against this might be that we should all be eating specific foods such as garlic, purple sweet potato, soya beans, and olive oil, which may have properties that promote longevity.¹³

However, this idea of superfoods may also be misleading as the term has no scientific or regulated definition, leaving it open to interpretation and overuse. For now, there is no scientific evidence that eating more of any one food will make you live longer.¹⁸ That doesn’t mean that so-called superfoods aren’t nutritious - they generally are - but many have similar nutrient makeups and benefits to comparable food, so they aren’t necessarily better than an alternative.

Antonio Vassallo, 100 years-old, and his wife Amina Fedollo, 93, pose in their house in Acciaroli, southern Italy. Their town is renowned for its low rates of heart disease and Alzheimer's, and has a disproportionately high number of centenarians in its population of about 2,000. Photo by Salvatore Laporta via Getty Images.

What about lifestyle?

The reality is that the secret to longevity may be as much about lifestyle as about diet. The 2004 study that coined the term Blue Zone stated that the reasons for the longevity of men in Nuoro Province were unclear.² But it noted that most longevity hotspots identified globally were in mountainous regions, showing how factors other than food may contribute to longevity.²

Many cultural similarities exist across the five Blue Zones today. In addition to a healthy diet, residents in all five Blue Zones consume only small amounts of tobacco and alcohol and restrict their calorie intake.¹⁴ Residents typically value family life, community, caregiving and social engagement and participate in daily exercise.

In the original Blue Zone study, the following factors are listed as the Power 9 principles that help ensure a longer and happier life:^14,15

• Moderate, regular physical activity

• Life purpose

• Stress reduction

• Moderate caloric intake

• Predominantly plant-based diet

• Moderate alcohol intake

• Engagement in spirituality or religion

• Engagement in family life, and

• Engagement in social life
  
  Even though we have this list, much of the information we rely on is anecdotal rather than scientific. So it’s difficult to determine how important diet and lifestyle individually are to longevity. But the power principles remind us that living longer doesn’t necessarily equate to well-being, and there are many social aspects to a long and happy life. And while no single diet can make us happier, food does play an essential role in healthy brain function and emotional regulation.

102-year-old marathon runner Fauja Singh at his house on March 20, 2014 in Jalandhar, India. Fauja Singh is an Indian centenarian marathon runner of Punjabi Sikh descent. He is a world record holder in his age bracket. Photo by Priyanka Parashar via Getty Images.

Does a good diet lead to well-being?

Some parts of the average Blue Zone diet contain foods that help with mental well-being, such as nuts and seeds, which contain fatty acids such as omega-3 that support brain function.¹⁶ Similarly, eating enough protein can support mental health because our brains use amino acids in protein to produce chemicals called neurotransmitters, which help regulate thoughts and feelings.¹⁶

Food is clearly an important part of our well-being, but it is part of a complex web of other factors - financial security, enough sleep, a fulfilling career, friends, and an intimate relationship with a partner.

The bottom line

People have been searching for ways to elongate their lives for centuries, but nobody has found the one thing that allows you to live forever. Ask your friend, and they might tell you the secret is walking three miles a day. Ask someone else, and they could prescribe a daily glass of whisky.

I asked my 91-year-old Gran, and she told me: “Have a dog and go out walking, keep your mind active and live life to the full as you want it.”

The truth is that nobody knows the definitive answer to living a long life. And the problem with relying on Blue Zones as the perfect example to live by is that it is impossible to replicate one location's environmental, social or dietary factors in another. Eating a healthy diet, getting enough movement, and social factors like community all play an essential part in longer, happier lives.