Poor diet is linked to one in five deaths worldwide, a major report has concluded.
The finding was published today, forming part of the Global Burden of Disease report, the most in-depth study of global mortality rates ever conducted.
Researchers at the University of Washington said the two extremes of inadequate nutrition in poor communities and unhealthy eating in richer populations kill a fifth of human beings.
The biggest driving factor is that millions of people are eating a diet which consists of too much salt and saturated fat, and not enough fruit, vegetables, nuts, seeds, omega 3, and whole grains, the authors warn.
"Among all forms of malnutrition, poor dietary habits - particularly low intake of healthy foods - is the leading risk factor for mortality," researchers concluded.
The studies, drawing from the input of 2,500 experts, also showed that one in seven people - 1.1 billion - are "living with mental health and substance use disorders".
Major depression ranked among the top ten causes of ill health in all but four of the 195 countries and territories covered.
Mental health services are chronically underfunded in most nations, especially in the developing world.
In China, only six percent of people coping with common mental illnesses such as depression or anxiety disorders or with substance abuse and dementia seek out a doctor, earlier research has shown.
Less than one percent of national healthcare budgets in China and India is allocated to mental health.
The global population afflicted with Alzheimer's or Parkinson's disease stood at 2.6 million worldwide in 2016, a more than 40 per cent surge from only a decade earlier.
Alcohol and drug use accounted for some 320,000 deaths, including 86,000 for opioids. Opioid abuse - mostly pharmaceutical - in the United States has reached epidemic proportions.
"We are facing a triad of trouble holding back many nations and communities - obesity, conflict and mental illness, including substance abuse disorders," said Christopher Murray, director of the Institute for Health Metrics and Evaluation at the University of Washington in Seattle, which centralized and analysed the millions of data points used the studies.
Deaths attributed to conflict and terrorism - notably in North Africa and the Middle East - exceeded 150,000 in 2016, a jump of 140 per cent compared to a decade earlier.
One bright spot was the better-than-expected health performance of several countries - including Ethiopia, the Maldives, Nepal, Niger, Portugal and Peru - that made outsized improvements in relation to national wealth, or GDP.
"These exemplar countries may provide information on successful policies that have helped to accelerate progress on health," said Murray.
In several cases, that headway stemmed in part from the rollout of antiretroviral treatments for HIV/AIDS.