Food, glorious food
We're anxious to try it
Three banquets a day
Our favourite diet
Just picture a great big steak
Fried, roasted or stewed
We can all identify with those classic lyrics from the musical Oliver. Just think about how much of our lives revolve around food. A lot! Consider how often conversations drift to when to eat, what to eat, what not to eat, where to eat, how much to eat, and with whom to eat. To be sure, eating is one of the great pleasures of life, and so is talking about it. We debate where the best pizza, best bagel, best croissant, best hummus, best burger, or best smoked meat can be found. (Actually, there is no debate about the latter…just ask anyone from Montreal.) And of course, with the current onslaught of nutritional information, discussions often gravitate towards the link between food and health. Vegetarian, vegan, carnivore, keto, Mediterranean, gluten-free, dairy-free, and intermittent-fasting diets all have their devotees and critics.
The attention paid to nutrition is well warranted. After all, besides water, food is the only raw material that enters our body. We are therefore constructed of what we eat! Our body breaks down food into its components and then reassembles these in various ways to form our tissues, bones, and the myriad molecules involved in the reactions that together constitute life. There can be no question that we really are what we eat, and that our health and, in turn, our life expectancy, is a function of what we put into our body.
Of course, food is not the only determinant of health. Genetics, activity level, exposure to microbes and to environmental toxins all play a role. But at least with food, we have some control over what we dig into. And therein lies a problem. What do we choose, and how much? There is no lack of nutritional research to consider. Since 2017, roughly 250,000 research papers have been published dealing with every aspect of nutrition. Many of these have explored the link between health and the major food groups, namely fruits, vegetables, whole or refined grains, nuts, legumes, dairy, sweeteners, eggs, fish, red and processed meat. As one might expect, given the large number of studies, diverse methodologies used, different populations examined, and researchers sometimes having vested interests, there is a fair degree of disagreement about the advice that should be offered to the public.
Now a team of Norwegian researchers has made a gallant attempt to quantify the risks and benefits of various dietary components in terms of modifying life expectancy. They have drawn on data available from the Global Burden of Disease (GBD) study, a collaborative ongoing effort by some 3500 researchers around the world who assess risk factors for mortality and disability from major diseases in some 204 countries. Combining life expectancy information from the GBD with a PubMed search for meta-analyses studies that examined dose-response data on the impact of various food groups on mortality allowed the researchers to estimate the change in life expectancy based on dietary choices. The result is a tabulation of the number of years lost or gained by altering the amounts of specific foods eaten.
It turns out that making dietary changes is worthwhile. A twenty-year-old man or woman who makes appropriate changes can increase their life expectancy by an astounding 10-13 years! If the change is made at age 60, the increase is somewhat less, 8-9 years, but even at age 80, life can be extended by about 3 years.
What dietary changes can bring about such an impressive lengthening of life? Luckily, you don’t have to starve yourself, you don’t have to guzzle supplements or develop a taste for some esoteric fruit or plant that grows in a remote rainforest. The proposed dietary changes as described in the paper published in the peer-reviewed journal, PLOS Medicine, are quite manageable. Let’s have a look.
Adding 200 grams of legumes a day will get you two extra years, as will increasing whole grain intake from 50 to 225 grams. Eating a handful of nuts (25 grams) will get you an extra 1.7 years, while 200 grams of fish will net half a year, as will 400 grams of fruit (an apple is about 200 grams, a half a cup of blueberries around 100). Adding 150 grams of vegetables adds a third of a year (cup and a half of broccoli), while dairy and white meat seem not to have any effect on longevity. Decreasing refined grains from 150 to 50 grams (a slice of white bread is 40 grams) will get you a year, as will cutting out sugar-sweetened beverages. Giving up red and processed meat will result in a gain of 3 years in life expectancy.
Remember though that statistics apply to populations, not to individuals whose longevity is determined by numerous factors other than diet, ranging from inherited traits and body weight to activity level and any chronic disease that may be present. While the specific number of years mentioned in the study may not be applicable to an individual, everyone is likely to benefit from paying attention to the data laboriously gathered and analyzed by the Norwegian scientists. Increase your intake of legumes, whole grains, nuts, vegetables, and fish while you cut back on sugar and red and processed meat. That is likely to give you more years and more occasions to debate the merits of this study.