Jeffrey Sachs is a professor and director of the Center for Sustainable Development at Columbia University. The opinions expressed in this commentary are his.

(CNN) America's powerful corporations made a killing with the passage of the Republican tax cuts. The tax cuts will hand trillions of dollars to the companies and their moneyed owners following a massive corporate lobbying campaign .

Yet the US government announced this month an even graver corporate killing. According to the Centers for Disease Control and Prevention (CDC), US life expectancy fell again last year for the second straight year, declining 0.1 year between 2015 and 2016.

And make no mistake -- America's health crisis is the result of greedy corporations and their reckless practices.

The US life expectancy is slipping further and further behind other high-income countries. According to the most recent comparative data of the Organization for Economic Cooperation and Development, US life expectancy in 2015 (at 78.7 years) ranked 27th out of 35 OECD countries, more than five years behind the leader, Japan (83.9 years), and roughly four years behind the next three countries, Spain (83.0), Switzerland (83.0) and Italy (82.6).

Yet Americans pay on average almost $10,000 per person per year for health care -- twice or even three times the cost in Canada and many European countries. So, then, what accounts for America's shorter life span?

One problem is the low value for money in America's healthcare spending. Unlike the highly regulated health systems abroad, America leaves much more of the pricing for drugs, procedures and hospital stays in the hands of the private sector, which exploits its market power by charging outrageous prices and leaving millions of Americans without coverage.

Another cause of America's lagging life expectancy is the nation's rising inequality of income. America's poor die much younger on average than America's rich, with a discrepancy of up to 10-15 years on average. The combination of overpriced American health care and poverty is lethal.

Two corporate-caused US epidemics -- obesity and opioid addictions -- add to the misery.

America's obesity epidemic is shortening the lives of Americans and burdening them with a range of chronic diseases, including coronary heart disease, type-II diabetes, hypertension and certain cancers. Obesity is also a risk factor for the onset of depression, while depression, in turn, contributes to the onset of obesity.

America's opioid epidemic is leading to soaring deaths from drug overdoses, and substance abuse more generally is contributing to soaring rates of suicide, addiction and suffering. The CDC calculates that there were 63,600 deaths from drug overdoses in 2016, and more than a tripling in the age-adjusted rate of drug-overdose deaths from 1999 to 2016.

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While the obesity and opioid epidemics are sometimes written off as "bad life choices," these epidemics are largely the handiworks of an irresponsible corporate sector. As University of California pediatric endocrinologist and neuroscientist Dr. Robert Lustig describes in his remarkable book, The Hacking of the American Mind, America's soaring obesity reflects a fast-food diet that has been deliberately stuffed with high-fructose corn syrup and various processed meats and grains that cause obesity.

American are being killed slowly and painfully by their own food industry. Yet instead of taking responsibility for the epidemic and doing something about it, most of the leaders of the food industry actively resist a change of direction and the needed changes in public-health regulation. The beverage industry, for example, is fighting strenuously against public health measures aimed at cutting America's deadly over-consumption of sugar-packed sodas. Sad to say, things -- human health, for one -- do not go better with soft drinks.

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The corporate hidden-hand is also present in the opioid epidemic. A recent expose in the New Yorker and lawsuits filed against Purdue Pharma, the maker of OxyContin, allege that the company pursued a marketing campaign that pushed OxyContin onto doctors. According to the article, Purdue allegedly did not adequately study the risks of OxyContin, paid off doctors to ignore them and pushed aggressive advertising despite growing concerns and evidence of an addiction crisis. While the company rejects this characterization and denies the allegations, drug makers -- at the very least -- failed to respond adequately to the growing alarm bells as the opioid epidemic soared. (Purdue has since issued a statement saying it is committed to helping in the fight against prescription opioid abuse and to supporting the recommendations of the Food and Drug Administration's Opioid Action Plan.)

Corporate power has run amok in American politics. Yet the mortality crisis is even worse. The health of the American people depends on restoring democratic oversight and regulation over powerful food and drug companies blinded by greed and arrogance.