The Most Important Risk Factor for Mortality Globally

Having a good diet not only helps you maintain a healthy weight, it can also prolong your life. A new study in Lancet has found that one in five deaths in the world is linked to bad diet, particularly eating too much salt and not enough fruit and whole grains.

‘The Global Burden of Disease’ in Lancet paper reported that bad diets are behind deaths caused by heart disease, type 2 diabetes and cancer. The paper is the most comprehensive analysis on the health effects of diet ever carried out.

The researchers behind the research believe that bad diet caused as many as 11 million deaths globally in 2017. More than five million of those were connected with too much salt and a lack of whole grains and fruit and vegetables. 

According to the study, bad diet kills more people each year than tobacco consumption. Seven million people die from smoking related diseases every year compared to 11 million from bad diet.

“Poor diet–related risk factors affect people independent of their age, gender, or socioeconomic background, while the magnitude of the problem varies, people in all countries are affected” said lead researcher, Dr Ashkan Afshin, from the University of Washington’s Institute for Health Metrics and Evaluation in Seattle. 

A team of researchers collected and analysed information on early death and disability from more than 350 diseases and injuries in 195 countries. Drawing from many sources (for example national nutrition surveys), the researchers reviewed information on adults age 25 and older, covering 27 years from 1990 to 2017.

15 dietary elements were examined: fruits, vegetables, legumes, whole grains, nuts and seeds, milk, fibre, calcium, omega-3 fatty acids from seafood, polyunsaturated fats, and diets high in red meat, processed meat, sugar-sweetened beverages, trans-fatty acids, and sodium.

Dr Afshin said the researchers cross-examined deaths and the 15 dietary elements and also looked at risk factors like high blood pressure, smoking, drinking, low physical activity and being overweight.

“When we ranked all of these risk factors — poor dietary factors overall ranked as the most important risk factor for mortality globally, causing more deaths than any other risk factor, including tobacco use, high systolic blood pressure, and alcohol use,” Dr Afshin said.

The Lancet paper also came up with a recommended daily intake for each dietary factor by estimating the intake needed to lower the chances of death.

The paper also found that people are not consuming enough nuts, seeds, and milk. On the other hand, they overconsumed sugar-sweetened beverages and processed meats. Ideally we should be drinking two cups of milk a day. We should also be eating about 125g of whole grains daily. Meanwhile we are eating almost double the amount of processed meat and salt than we should be.

The data reveals that in the same year, around 255 million years of healthy life were lost due to disability, illness or early death (disability-adjusted life-years) because of what people ate day-to-day.

The basic message for us is that rather than focussing on cutting down on junk food, aim to increase your consumption of good food.

“Historically, most of the attention in nutrition has been focused on decreasing the intake of unhealthy food,” Dr Afshin said. “This study suggests that the major problem is not the high intake of unhealthy food, but the low intake of healthy food.

“Generally in real life, people do substitution. When they increase the consumption of something, they decrease the consumption of other things,”

But the biggest barrier to following this advice may be a lack of good food in some countries.

“In many countries, there is not sufficient food available to actually meet the recommendations,” he said.

The world’s highest rate of diet-related deaths was in Uzbekistan, one of the poorest countries of the world; meanwhile the people of Israel have the healthiest diet, followed by France, Spain, Japan, and Andorra.

The research ranked countries according to the number of deaths related to poor diet. Australia ranked in the top 30 for lowest rates of dietary-related deaths.

The paper’s authors found that there was no region in the world which practiced a perfect diet, featuring all the right levels of healthy foods.

Some regions lead when it comes to eating specific healthy foods:

• People in central Asia ate the most vegetables.
• People living in high-income Asia Pacific countries eat enough seafood omega-3 fatty acids.
• In the Caribbean, tropical Latin America, south Asia, western sub-Saharan Africa, and eastern sub-Saharan Africa, people ate enough legumes.

Countries that have a mainly Mediterranean diet eat more fruit, vegetables, nuts and legumes, said Dr Afshin, naming Lebanon, Israel and Iran among the better performers. “But no country has an optimal level of consumption of all the health foods. Even in countries that have a Mediterranean diet, the current intake of many other dietary factors is not optimal.”

Dr Afshin said one of the weaknesses of the study was a lack of consistent data from some countries. Much of the dietary information came from self-reported nutritional surveys when people tend to overestimate or underestimate what and how much they ate.

Dr Afshin said the findings also demonstrate that national campaigns to get people to eat better are not working.  He says governments should become more interventionist when it comes to national diet.

Another author Dr Christopher Murray said the 11 million deaths included about 10 million from cardiovascular disease, 913,000 from cancer and almost 339,000 from type 2 diabetes.

“This study affirms what many have thought for several years – that poor diet is responsible for more deaths than any other risk factor in the world,” Dr Murray said.

“The paper also highlights the need for comprehensive interventions to promote the production, distribution, and consumption of healthy foods across all nations,” 

Another co-author of the study, Prof Walter Willett from Harvard University, said that the findings were consistent with a recent analysis of the benefits of going vegetarian.

“Adoption of diets emphasising soy foods, beans and other healthy plant sources of protein will have important benefits for both human and planetary health,” he said.

The study was funded by the Bill & Melinda Gates Foundation.