Best diet for longevity

I previously discussed in Insight 8 that severe caloric restriction retards the onset of many diseases and increases longevity in animal models of aging (including the monkey).  I subsequently presented the status of the future caloric-mimetic drugs. These drugs are predicted to offer the same benefits (health and longevity) of caloric restriction minus the pain of caloric restriction (Insight 9).  However, in the interim until the advent of efficacious caloric-mimetic drugs, the question remains as to what is the best diet for longevity building.  The best answer to date is the Mediterranean diet.  It is the diet with the most convincing scientific support.  Most importantly, adherence to this diet is associated with a decrease in the incidence of cardiovascular disease, the major cause of death in our society.  As a result, disease reduction indirectly increases lifespan.  

Components of the Mediterranean Diet

The Mediterranean diet entails consumption of whole grains, legumes, fruits, vegetables, nuts, fish and olive oil, wine in moderation, and a low-moderate intake of meat, dairy products, processed foods and sweets (Vitale et al., 2018).  This ~2000 calorie/day diet derives more calories from plant based foods than from meat based foods and fat consumption is largely from mono- and polyunsaturated fats.  More details are presented in the adjacent table.  This table is the result of an extensive systemic review (59 studies) of the health effects of the Mediterranean diet (D’Alessandro et al., 2019).  The authors were able to assess the effect of each food group on disease prevention. From that, they developed the frequency and serving size of the components of this diet needed to achieve these health benefits.      

Origin of the Mediterranean diet

A study called Seven Countries Study of Cardiovascular Diseases began in the late 1950s and continued for some 50 years.  This seminal study tracked over 12,000 middle-aged men in North America, Northern Europe, and Southern Europe. It correlated dietary patterns with the incidence and mortality rates for coronary heart disease (CHD) and overall mortality (Menotti  and Puddu, 2015).  The striking findings showed that the incidence of CHD, other cardiovascular diseases and overall mortality was lower in southern Europe (Mediterranean countries and Japan) than anywhere else.  This improved health and longevity significantly correlated with decreased saturated fat consumption (low levels of serum cholesterol) and increased calorie intake from plant foods relative to animal meats.  In other words, this became known as the Mediterranean diet.

Proven benefits of the Mediterranean diet

There are numerous observational studies and clinical trials on the effects of adherence to the Mediterranean diet to health outcomes.  To make sense of the wealth of data, meta-analysis combines results from the  most rigorous studies to yield what are considered substantiated and valid conclusions.  The most recent of these meta analysis (Sofi et al., 2008; Dinu et al., 2018) evaluated 13 observational studies and 16 randomized clinical trials with regard to 37 different health outcomes. The results show adherence to the Mediterranean diet yields lower mortality for:

1. Cardiovascular disease, Coronary heart disease, Heart attack
2. Neurodegenerative diseases
3. Cancers
4. Diabetes
5. All causes

However, there are limitations to studies assessing dietary patterns since they rely on validation of dietary questionnaires.  Hence, the need for the meta analysis that shows with a high degree of confidence that adherence to the Mediterranean diet compared to a non Mediterranean diet e.g. western diet, consistently yields valuable health benefits. 

Future – how the Mediterranean diet works

Several studies have endeavored to probe the underlying mechanism(s) of the Mediterranean diet on health benefits.  As a result, it has been shown, albeit in small studies, that the adherence to the Mediterranean diet for 6 months to one year lowers blood pressure (Davis et al., 2017; Jennings et al., 2019), improves dynamic blood flow (Davis et al., 2017), decreases proinflammatory mediators (Dyer et al., 2017) and reduces arterial stiffness (Jennings et al., 2019).

Other diets e.g. Okinawa, DASH and Portfolio will be discussed in my next blog.