How eating can take off or add years to our life


Driven by health and environmental concerns, an increasing number of people are adopting a more plant-based diet. But what can we really hope to gain? We met with Professor Olivier Jolliet from the University of Michigan, who has developed a tool to provide clear answers to this question.


Who is Olivier Jolliet?

Olivier Jolliet is a professor at the University of Michigan and a founding member of the Risk Science Center. He works on the environmental risk and impact of chemicals and innovative technologies. He co-initiated the United Nations Environment Program (UNEP)/SETAC Life Cycle Initiative, and is the scientific lead for the life cycle impact assessment programme. He is a reviewer for several scientific journals.

How significant is diet among health risk factors?

O.J. ‘Food, like tobacco, is the most important factor that we can control to improve our health. What we eat has direct and indirect effects on our quality of life and our life expectancy, especially if we are overweight. It is also an important factor for the environment. This is what we wanted to quantify in our research.’

What was your approach?

O.J. ‘We started off with data from the Global Burden of Disease (GBD), which lists the top 15 dietary and nutritional risk factors for health. We calculated these effects for over 5,800 types of food and translated them into minutes of life gained or lost.’

Can you give us some examples? 

O.J. ‘Take a hot dog: its 61 g of processed meat translate into 27 minutes of life lost; the gram of salt in the hot dog costs you an additional seven minutes of life, the trans fatty acid content another three minutes. This is only partially compensated by the one minute of life gained by the presence of fibre and polyunsaturated fats. The result: 36 minutes of life lost for a hot dog… Conversely, by eating 23 g of nuts and seeds, we can gain 25 minutes of life.’

Is what is good for our health also good for the planet? 

O.J. ‘We analysed the same set of foods on the basis of 18 environmental criteria. Often there is a correlation, but not always. Salmon, for example, is quite good for your health, but not so good for the environment. In the case of pizza, its environmental impact matches its nutritional impact: the more meat and the fewer vegetables it contains, the worse it is for the environment and our health.’

What can we hope to gain health and environment wise by moving towards a more plant-based diet? 

O.J. ‘Our study found that an average American can gain up to 48 minutes of life per day and reduce their carbon footprint by a third by replacing 210 kcal of beef and processed meats with a mix of whole grains, fruits, vegetables, nuts, pulses, and certain types of seafood.’

What are the priorities?

O.J. ‘First of all, we have to do everything in our power to offer a variety of good-quality fruits and vegetables at affordable prices. I think this can be achieved through sustainable rather than purely organic production, and through agricultural subsidies that are better distributed according to the environmental impact of different crops and farms. On an individual level, we can eat seasonal fruit and vegetables; in winter, opt for canned or frozen food. Eating seasonally is even more important for the environment than eating locally, especially if the local production is in greenhouses. When it comes to replacing certain foods in our diet, the priority is to cut down on beef and processed meats, and replace them with plant-based foods.’

How do you get people to buy into these changes?

O.J. ‘Our message is positive and simple, and encourages action. There was a huge public response as soon as we published the results of our research: the message that every hot dog could shorten your life by 36 minutes was an immediate and global viral success. I often repeat what I was told children began to say: they started asking their parents for “a few minutes of life”, rather than asking for an apple. This shows that the message has been understood and accepted, and that it is being used in a fun way, even by children.’