There is an abundance of information on the internet about the healthiest way to eat, some of it questionable and some offering well-founded evidence-based knowledge. How is one to know who to listen to?
When it comes to eating for health, the goal is not simply about long lifespan. Even more essential is healthspan, lifelong health over many years. Let’s face it, the joy of extending lifespan only exists if good health comes along with it. Though human lifespan has increased, evidence shows that the healthspan has remained constant. This indicates that the additional years of life gained are lived in poor health. (1)
Deteriorating health during aging is rarely due to genetics; debilities largely stem from lifestyle (diet, physical activity, stress, sleep habits, alcohol use) or from the environment (community, neighbourhood, socioeconomic status). Consequently, it is important when aiming for a long healthspan to adopt habits that will lead to continued healthiness. (1)
It turns out that what we choose to eat is a key factor in the determination of both lifespan and healthspan and, fortunately, this is a variable that can be modified by anyone with the desire to do so. In April 2022, the results of comprehensive new research seeking an optimal diet for extending healthspan were published by Dr. Valter Longo and his team at the Longevity Institute and Davis School of Gerontology, University of Southern California in Los Angeles, California. These researchers have been exploring feasible nutritional strategies for delaying aging and preventing disease for many years. (2)
This review is multi-faceted and encompasses a wide range of nutritional research amassed over many decades. Included are papers examining the link between nutrients, genes and longevity in short-lived simple organisms like yeasts, worms and flies, and then carrying these links into clinical and epidemiological studies of primates and human beings, including centenarians. Many different diet types were scrutinized – high calorie diets, low calorie diets, low carbohydrate keto diets, low protein/amino acid diets, low fat diets, high fat diets, vegan diets and fasting. Specific factors that affect metabolic pathways in humans to alter longevity were investigated as well as the markers for disease risk that these interactions influence such as levels of insulin, C-reactive protein (a measure of inflammation), IGF-1 (insulin-like growth factor 1) and cholesterol. Ultimately, all this data was analyzed for its effects on longevity. The end result was a “longevity diet”, firmly based on all available evidence, and considered to offer the best way of eating for a longer and healthier life. (2)
Authors of this study emphasize that dietary patterns that promote healthy longevity are complex and cannot be elucidated through simple epidemiological comparisons of, for example, high vs low consumption focusing on one isolated macronutrient. The overall quality and source of the totality of the foods being eaten is what exerts the impact that foods exert on long-lasting health. Multi-disciplinary assessments of nutrition and healthspan through carefully controlled clinical trials are required, variables such as age, sex and metabolic status need to be taken into account as well as outcomes from studies of long-lived populations. (2)
What is a Longevity Diet (2)
In their conclusion, this research team presented a final analysis of all of the existing evidence regarding nutrition and a long and healthy life, including the multiple dietary aspects involved, and linked them to nutritional strategies. The resulting characteristics of a longevity diet are as follows;
- Moderate to high carbohydrate intake from mostly non-refined plant-based sources, including nuts, to provide 45 to 60% of calories from carbohydrates
- Low but sufficient protein from largely plant-based sources to supply 10 to 15% of calories from protein
- Enough plant-based fats to deliver about 25 to 35% of calories from fats
- The day’s meals are to be consumed within a window of 11 to 12 hours creating a daily period of fasting for 12 to 13 hours. Intermittent fasting (such as eating only within a 6- to 8-hour period every day or eating regularly on 5 days a week and consuming only 500 to 600 calories for each of the other two days) also shows benefits but is more difficult to adhere to and proven to be no better for reducing weight and body fat or risk factors associated with disease. Lengthier periods of fasting can be added if desired every 3 to 4 months.
In practical terms, a diet for longevity means eating lots of legumes, whole grains, vegetables and fruits; some nuts, seeds and dark chocolate; no red meat or processed meat; very low amounts of fish and white meat; and low amounts of sugar and refined grains.
The researchers note that these recommendations can be easily adapted to specific individuals, taking into account health status, sex, age and genetics.
How does a longevity diet affect health? (2)
The nutritional patterns of a longevity diet impact health through many different mechanisms
- They promote low insulin levels and lowered insulin resistance
Insulin resistance reduces the ability of the body to use insulin effectively as a regulator of blood sugar levels and inhibits its role in the metabolism of carbohydrates, fat and protein. Insulin resistance is the main cause of type-2 diabetes. (3)
- They lower fat levels in adipose (fat) tissue
Adipose tissue is an active organ in the endocrine system. Excess stored fat can cause problems for the immune system, the regulation of glucose and cholesterol and the maintenance of insulin sensitivity. (4)
- They moderate activity of growth hormone (GH) and insulin-like growth factor-1 (IGF-1). IGF-1 is a hormone that helps control the growth and development of body tissues. Large amounts of protein increase IGF-1 levels when it is needed early in life. However, if this continues into adulthood it can lead to serious health complications such as cancer. GH can stimulate the production of IGF-1. (5)
- They reduce mTOR signalling
mTOR accelerates the rate of cell functions and leads to early cell death, the development of diabetes and a shortened lifespan. (6)
- They increase autophagy
Autophagy is a natural, self-preservation mechanism that removes unnecessary or damaged parts of a cell and recycles other cell parts. (7)
The result of these changes are…
- Improved metabolic function
Metabolic function encompasses the complex body processes that convert foods into energy to fuel body functions. It includes circulating blood, breathing, digesting food, growing and repairing cells and managing hormones. (8)
- Reduced inflammation
Acute inflammation from sudden body damage such as a cut finger starts the healing process and is over quickly. But when inflammation becomes chronic, the body sends out inflammatory signals even when there is no danger. Chronic inflammation is associated with heart disease, cancer, type-2 diabetes, Alzheimer’s disease, rheumatoid arthritis and asthma. (9)
- Delayed immunosenescence
Immunosenescence is deterioration of the immune system.
- Reduced oxidative damage
Oxidative damage is an imbalance between free radicals and antioxidants in the body that can injure organs and tissues and result in disease. (10)
- Improved proteostasis
Proteostasis is the maintenance of proteins from their precise formation to their correct functioning through to their degradation and death. Diseases and aging cause a decline in proteostasis. (11)
All this adds up to delayed aging and reduction in the risk factors for and the incidence of age-related diseases including diabetes, cancer, cardiovascular disease and neurodegenerative diseases.
A recent study using Global Burden of Disease 2019 data from the US, China and Europe supports the longevity diet. It illustrates that a long-term change from a typical western diet to an optimal diet rich in legumes, whole grains and nuts and low in red and processed meats is linked to an increase in life expectancy of 10.7 years in females and 13 years in males if started at the age of 20. When started at the age of 60, the increase in life expectancy is over 8 years. (12)
This extensive deep dive into the anatomy of a diet for longevity is not a prescription for a calorie-restrictive eating plan. Instead, it offers a set of lifelong eating habits that promote health into old age. Its foundation is the plethora of edible plant food choices available with their rich content of vital nutrients such as vitamins, minerals, antioxidants and phytochemicals. If you are hoping to enjoy robust health throughout life, here is the evidence to show you the way. (13)
2 Longo, V.D., Anderson, R. M. Nutrition, longevity and disease: From molecular mechanisms to interventions. Cell. April 28, 2022. 185(9): 1455-1470. Doi: https://doi.org/10.1016/j.cell.2022.04.002.
6 Zoncu, R., Efeyan, A., Sabatini, D.M. mTOR: from growth signal integration to cancer, diabetes and ageing. Nat Rev Mol Cell Biol. 2011 Jan; 12(1):21-35
7 Kobayashi, S. Choose Delicately and Reuse Adequately: The Newly Revealed Process of Autophagy. Biological and Pharmaceutical Bulletin. 2015; 38(8): 1098-1103. Doi.org/10.1248/bpb.b15-00096. https://www.jstage.jst.go.jp/article/bpb/38/8/38_b15-00096/_article/-char/en,
11 Verma, K., Verma, M., Chaphalkar, A., Chakraborty, K. Recent advances in understanding the role of proteostasis. Fac Rev. 2021 Sep 15; 10:72. Doi: 10.12703/r/10-72. PMID: 34632458; PMCID: PMC8483240.
12 Fadnes, L.T., Økland J,-M., Haaland, Ø.A., Johansson, K.A. Estimating impact of food choices on life expectancy: A modeling study. 2022. PLoS Med 19, e1003889.