Longevity and macronutrients: The Connection

We’ve looked at a host of different factors that can affect our life expectancy, from dietary choices to social connections, demographics, careers, family dynamics and more. But, in a recent study published last December by the Proceedings of the National Academy of Sciences (PNAS), a link was found that connected longevity to macronutrients.

What is a macronutrient, you ask? A macronutrient is a nutrient that we need a large amount of – they are essentially the building blocks that provide us with daily energy. There are seven main categories of macronutrients: carbohydrates, fats, dietary fibre, minerals, proteins, vitamins and water. While these categories encompass a wide range of foods, what matters most is how much we eat of each of these items, as well as the stage of life we are in – our needs and the benefits of these macronutrients change, depending on age.

Last December’s study reviewed several experiments, in which it was determined that energy intake and the balance of macronutrients determine life span and patterns of age-specific mortality. Our intake of macronutrients has to be adjusted throughout our lives based on our needs: the same study put forth that early in life, equal amounts of fat and carbohydrate are predicted to improve survival but, as we age, reducing fat in exchange for carbohydrates is associated with the lowest rates of mortality.

In the last decade, scientists have been closely analyzing how macronutrients impact the health and overall life expectancies of mice. Median lifespan was greatest for animals whose intakes were low in protein and high in carbohydrates, but was not influenced by total calorie intake. Additionally, the results were consistent with reports in invertebrates showing that the ratio of proteins to carbohydrates in the diet influences lifespan (Science Direct).

According to the Oxford University Press, caloric restriction is the major nutritional intervention that historically has been shown to influence lifespan and/or health span in many animals. Studies have suggested that a reduction in protein intake can also increase lifespan, albeit not as dramatically as caloric restriction.

More recent research based on nutrition has tried to define the effects of nutrition on aging over a broad landscape of dietary macronutrients and energy content. These studies, when performed on insects and mice, indicated that animals with ad libitum access to low-protein, high-carbohydrate diets have the longest lifespans.

Remarkably, the optimum content and ratio of dietary protein to carbohydrates for aging in experimental animals are almost identical to those in the traditional diets of the people on the island of Okinawa. This area of Japan, which we have looked at before, has the most highly concentrated number of centenarians in the world. The energy from their diets was derived from 9% protein and 85% carbohydrates.

If we go back to the most recent PNAS study, it’s not just the consumption of macronutrients that increases longevity – instead, it’s the availability of macronutrients that’s a strong predictor of mortality patterns and demonstrates how the ideal balance of supplies for maximizing lifespan changes with age. This research indicates that it’s a balance of different macronutrients – not the elimination of any – that improves the chance of survival.

Cooking Light offered some great tips on how to add macronutrients to your diet:

  • If you’re hungry, add more protein as it is the most satiating nutrient. More fibre is also filling.
  • If you’re tired, add more fibrous veggies to ensure sufficient energy from carbs.
  • If you’re not losing weight, lower your carbohydrate intake, especially with dinner.
  • If you have sugar cravings, balance your blood sugar better with more protein and fibre and remove all sugar.
  • If you are losing weight too fast, add five to six bites of starch, such as sweet potato, oatmeal or squash, with one meal per day.
  • If you are losing muscle mass, add more protein – ideally, an extra five to six bites of protein per day – and add strength training to your workouts.

by Jennifer Cox