Tuesday, October 19, 2021

Low-sodium diets: What are the ‘Blue Zones’ diet?

What is the Blue Zones diet?

It’s a radical approach to eating that’s gaining ground on popular weight-loss plans.

Looking more in the vein of The Master Cleanse and Dukan, it’s a weight-management programme that has found success in the Mediterranean region.

Writing in The Lancet, researchers announced they have used three years of tracking data on the composition of the diets of more than 30,000 people in seven diverse “Blue Zones”: Okinawa, Japan; Sardinia, Italy; and the Northern Mariana Islands, Micronesia, and the Marshall Islands, all located in the Pacific Ocean. And what they found was that when it came to managing their weight, those whose diets followed this simple list of “five Blue Zones” fared better.

In their analysis, the researchers compared three approaches to nutrition: 1) eating foods high in fibre and whole grains, 2) eating low-sodium (low sodium) foods, and 3) an eat-clean diet, which is calorie-restricted while being rich in a mix of the fruit, vegetables, nuts, dairy, legumes, and seeds for which most of the seven countries in the Blue Zones are known.

The Blue Zones diets are all based on ancient Mediterranean diets that the researchers believe align with how humans should eat to have a longer life.

Why is this the case?

Basically, low sodium is associated with improved health. There is a human body function called what researchers call “satiety”, which depends on the ratio of water- to salt-to-content ratio of a food. A standard Mediterranean diet with a high ratio of water-to-salt-content has been linked to less hunger, less sodium cravings, and people usually eat less of a particular food as a result. And it is also recommended in the EU Health guidelines.

Fiber is associated with lowering blood sugar levels, making people feel full longer and reducing the risk of obesity and diabetes.

“Our results suggest that a healthier diet with a reduced intake of sodium in adults improves health, while a lower fat diet and more plant-based and whole grain options can have the opposite effect,” wrote the lead researchers, Suraya Shukla and Stephen Halbrook.

How did they measure diets?

To evaluate whether the Blue Zones diets worked, researchers gathered diet records for more than 35,000 adults and children who were part of a national diabetes study (UCL). They compared the diets to those on the UK’s Weight Watchers plan.

The researchers tracked the participants’ intake of either 1,200 calories a day (with just the fat, meat, potatoes, and milk products of the Blue Zones diet), 1,500 calories a day (with the UK Weight Watchers plan) or a compromise. This mimicked what the diets would deliver to US and French adults.

This latter group could make up to 2,000 or 2,300 calories by swapping the Blue Zones diet for the UK Weight Watchers’ diet and eating 1,600 or 1,800 calories of fats, meat, and potatoes, respectively. These diets had to all have whole grains, fruits, vegetables, nuts, legumes, and seeds, and a reduction in sodium or one of the health-promoting foods.

What else did they find?

Low-sodium diets didn’t appear to lead to lower weight, cholesterol, or blood sugar levels. And the six diets that have been shown to succeed in obesity prevention fail to deliver the full Blue Zones package.

The Blue Zones diets are all based on ancient Mediterranean diets that the researchers believe align with how humans should eat to have a longer life. The most common advice the researchers heard was to eat a Blue Zones-style diet.

Why eat low-sodium diets?

One thing that struck the researchers was how large a difference there was in how much participants eat of certain foods. “Eating salt is not necessary, but it is common to eat too much,” said Mr Halbrook. “Some (Blue Zones) people eat 12 grams of salt a day.”

In the UK, salt is classified as 4.5 grams per kilogramme of body weight; in Britain, the maximum salt allowed is 4.8 grams. A diet of 1,200 calories a day (the Blue Zones) can still have 7 grams of salt, as can diets of 1,500 or 2,000 calories daily.

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