Rainbow Diet

Low-cal Mediterranean diet rejuvenates the immune system

Professor Valter Longo has shown that using a fast or a low-calorie Mediterranean Diet for five days a month improves the immune system, the response to vaccination, and reduces weight, fat levels, fasting blood sugar and blood pressure, encouraging longevity.

In an old and damaged immune system, fasting encourages stem cell production of new white immune cells. 

Professor Valter Longo, a biochemist and director of the University of Southern California Longevity Institute, has been investigating exactly how fasting (and diets that mimic fasting’s effects) can help immune function. This obviously has implications on longevity, on diseases from cardiovascular to cancer, and even on the body’s ability to deal with viral infections including Govid-19 and vaccinations.

“Fasting, and fasting-mimicking diets, appear to get rid of damaged or misguided cells and replace them with younger and more effective immune cells,” said Longo. 

Intermittent fasting

At the onset of fasting, the weaker, older white cells die off, being replaced with healthy infection-fighting cells when the fast ends and ‘normal’ eating recommences. With older people and weaker immune systems, other studies have shown that there may only be a 50 per cent level of antibody production when using a vaccine. Not only do the studies show that fasting improves these figures, but the body seems more able to respond to infection when actually on a fast!

“We also want to see if certain dietary interventions can make a virus less infectious or cause fewer negative effects,” Longo says.

Longo also uses a ‘fasting-mimicking’ diet – a low calorie Mediterranean diet – and early trials have shown that this diet reduces waistlines and weight, total body fat, blood pressure, inflammation (C-Reactive protein), IGF-1 and fasting blood glucose. The Rainbow diet also appeared to sensitize patients’ cancer cells to chemotherapy and reduce side-effects. 

This is not ‘time-restricted fasting’, where you don’t eat between, say, 6 pm and 10 am. This is Intermittent Fasting. The big difference is that time restricted fasting is essentially a weight loss program with resulting health benefits, whereas when people fast for more than 24 hours, hormonal changes occur. For example, after 24 hours the brain produces Sirtuin 1, which a health and longevity promoter, and helps condition healthy cells to a lower calorie environment, reducing insulin levels and inflammation in the body.

How long do these fasting periods last? Just five days each month seems to be enough. Rather than using a restrictive low calorie diet, Longo plumps for a low-calorie Mediterranean diet or a ‘balanced pescatarian diet’.

Research on monkeys has shown that simply reducing calories without malnutrition, can extend healthy life spans. Both cancer and cardiovascular disease in calorie-restricted monkeys run at about 50 per cent of normal levels. Sirtuin 1 plays a big role in this.

Go to: Fasting, calorie restriction and cancer 


  1. Medical Express, April 2020; USC: 

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