Science, at its best, leads to changes in policy that make everyone’s life better. But science alone cannot shape policy; policy is also influenced by politics, opinions, deeply held beliefs, and advocacy.

As surgeon general, I based all of my reports on the best available public health science, but they did not always lead to a change in policy. Sometimes that takes years. We know, for example, that even after 1964’s “Smoking and Health: Report of the Advisory Committee of the Surgeon General of the Public Health Service” documented concerns about cigarettes, it was not until 1972 that tobacco advertising was prohibited, and it was another 22 years before California became the first state to prohibit smoking in public places; as of March 2019, 28 states have such laws.

This dynamic interaction among science, policy, and practice is basic to progress in lifestyle and healthy living. In the area of smoking and health, we have perhaps had the most experience and made the most progress, but there are many other examples. It is because of science that we have vaccines that have eliminated and even eradicated diseases. It is because of science that we have reduced deaths from cardiovascular disease and cancer and diabetes. It is because of science that we can help people with “unquiet” minds, such as those with bipolar disease, lead productive lives.

What those experiences have taught us is that in the face of political or ideological influences, it is important to continue to mount the scientific data and arguments in pursuit of policy change. But understanding where science can have the most impact is equally critical. In 2009, the World Health Organization’s Commission on Social Determinants of Health, on which I served, reported after a worldwide study that social determinants of health—the conditions into which people are born, live, grow, learn, work, age, and die—had a much greater effect on health outcomes than did health care.

It is important to continue to mount the scientific data and arguments in pursuit of policy change. But understanding where science can have the most impact is equally critical.

For example, predominantly White neighborhoods have four times more supermarkets than predominantly Black neighborhoods, and we know that people who live in communities with poor access to affordable fruits and vegetables are more likely to suffer from obesity, diabetes, and other diet-related problems than those who live where healthy and nutritious food is readily available. Yet such conditions are controlled by money, power, and influence and can be changed only when policies that affect them are changed.

It is perhaps in regard to social determinants of health that science, especially when wielded by effective leadership, can be most instrumental in driving new policy and improving lives. Leadership can intervene to improve the health of individuals and communities at three key points: downstream, midstream, and upstream. Downstream is the level of individual health that can be improved through education, science, and medicine. Midstream is the community level and involves mitigating environmental threats, such as lead and other toxins; providing safe places for physical activity; and ensuring that institutions, such as schools and workplaces, promote the health of those who use them. Upstream is where policies are made that affect what happens midstream and downstream.

I always emphasize that these are not places, but functions. Policies are often made in the home or school, not just in the houses of government. And the arrow goes both ways: What happens downstream, whether science, practice, health care, or education, can lead to enhancements in policies from upstream. For instance, the Quality Parenting Program at the Satcher Health Leadership Institute at the Morehouse School of Medicine evaluates its impact on participants in the hope that the findings will influence policy and lead to investments to improve children’s well-being, development, and school readiness. And indeed, the National Institutes of Health has already responded to outcome data showing a reduction in depression among participating Black mothers by supporting the program’s replication in 12 states. Thus, a practice downstream, when properly documented, can improve policies upstream.

In particular, public health and public health science are especially important to this process of improving the health of individuals and communities and the policies that affect them. In 1988, the Institute of Medicine, now the National Academy of Medicine, defined public health as “the collective efforts of a society to create the conditions in which people can be healthy.” I have come to embrace this definition, with the understanding that “the conditions” rely on the right policies being in place. And with the newfound appreciation for the importance of social determinants of health, the definition takes on new significance. In 2005, colleagues and I published an article titled “What If We Were Equal?” in the journal Health Affairs. In it, we attempted to define the magnitude of health disparities in the United States by comparing the mortality rates of African Americans with those of White people, and we were able to show that if those rates had been equal in the 20th century, 83,500 fewer African Americans would have died in the year 2000 alone. In light of the WHO commission’s report on social determinants of health, those findings are given new focus, most notably that relative physical inactivity is virtually predetermined in communities that lack safe places to be physically active, just as the absence of grocery stores limits access to fresh fruits and vegetables.

This same broadening understanding of social determinants of health has informed significant policy agendas. Each decade, the U.S. Department of Health and Human Services releases its Healthy People goals, which outline the nation’s public health objectives and tools for measuring progress. The major difference between the goals of Healthy People 2010 and Healthy People 2020 is that the 2020 document incorporated social determinants of health in terms of problems and solutions. Similarly, WHO set the goal of “global health equity” and began working toward it. The evolution of the Healthy People initiative and of WHO’s efforts shows that, although science is not definitive and does not have the final word in policy debates, we still must continue to do the science and repeat studies. When people come together to listen to and hear each other and try to arrive at reasonable decisions, make important decisions, or invest significant resources that promote societal health, they generally want to know what the science shows.

Science is rigorous and begins by defining critical questions for pursuit. And it never ends; one set of questions generally leads to the proposition of another set of questions. Since the surgeon general’s report of 1964 showed that smoking was associated with lung cancer and heart disease, we have continued to learn more about the harmful effects of smoking, and scientific research has informed new policies and practices. In 1970, President Richard Nixon signed a law banning the advertisement of tobacco on television and radio. In 1995, California outlawed smoking in public places. Later, science determined that almost 90% of adult smokers became addicted by age 18, which eventually led to a policy forbidding the sale of tobacco to children. And between 2000, when I released the surgeon general’s report on women and smoking, and 2014, when the 50th anniversary surgeon general’s report came out, at least six new health defects associated with smoking had been reported.

And though the science never ends in any public health arena, there comes a point when the evidence is strong enough where we must insist that our practices adapt to our current science. Surgeon General Luther L. Terry did this in 1964 when he declared that the evidence of a link between smoking and lung cancer and cardiovascular disease was overwhelming. That declaration led to new policies and practices, and as a result smoking in the United States declined from 42% in 1965 to 14% in 2017.

Data Points

1994: California became the first state to prohibit smoking in public places.

Data Points

This was almost 30 years after the Surgeon General of the United States documented concerns about cigarettes, and 22 years after tobacco advertising was prohibited in the United States.

Data Points

2009: The World Health Organization reported, after a worldwide study, that social determinants of health had a much greater affect on health outcomes than did health care.

Data Points

Social determinants of health are conditions into which people are born, live, grow, learn, work, age, and die.

Data Points

4x more: The number of supermarkets in predominantly White neighborhoods versus predominantly Black neighborhoods.

Data Points

People who live in communities with poor access to affordable fruits and vegetables are more likely to suffer from obesity, diabetes, and other diet-related problems.

Today, the decline continues, not only in our country, but globally. In 2003, the WHO Framework Convention on Tobacco Control, a global tobacco control treaty, led to a worldwide policy related to exposure of children to smoking. Now, even in developing countries, smoking is declining and lives are being saved because over the years science builds on science.

Nevertheless, I am certain that there are still people who don’t agree that smoking is harmful to health. They are influenced by deeply held beliefs, by money, and certainly by the political process. The practice of smoking has not been easy to influence, despite the science. Similarly, my Surgeon General’s Prescription in 2000 was an attempt to inform Americans and urge them to be more physically active, consume more fruits and vegetables and fewer fats and sweets, and avoid toxins such as tobacco and illicit drugs. But it is clear to me now that, rather than focusing mainly on the upstream policy, the best way to deal with these behaviors is to use science to drive changes in the social determinants that directly affect decisions made downstream and midstream—to remove barriers to healthy choices; provide incentives for physical activity, good nutrition, and smoking cessation; and ensure that communities are safe and provide the facilities that individuals need to live healthy lives.

This is, appropriately, a circular process of new science, new policy, better practices, and new questions arising from observation and practice. Yet the question that gives rise to that science may begin with a practice as the basis of concern, or it may be a policy, and those concerns and questions often lead to new science. The dramatic decline in physical education in schools between 1980 and 2000 was thought to be good for academic rigor and performance. Upon closer examination, however, a commensurate increase in obesity was taking place, including a tripling among children. The science also revealed that children who were physically active and ate a good breakfast performed better academically. Thus, examination of practice and the policies behind them revealed that they were out of step with good science. In this way, the science-policy-practice cycle, though sometimes slow and rarely smooth, continues to build our knowledge and help us thrive.

Medicine is a science in the sense that we are committed to practice that which is consistent with the state of science. We never stop asking questions, and over time our practice improves. Today, we do not diagnose or treat diabetes and hypertension the way we did when I was a student. We have developed new science, and it has reshaped our practice.

One of the beauties of science is that it always welcomes new questions, debates, and challenges. The scientific process must always be open and be opening new horizons in our minds, our lives, and our environments.

The Takeaway

The dynamic interaction between science, policy, and practice is basic to progress in healthy living.

David Satcher is the founding director of the Satcher Health Leadership Institute and a professor at Morehouse School of Medicine. A former director of the Centers for Disease Control and Prevention, he was the 16th surgeon general of the United States. His essay is adapted from his book My Quest for Health Equity, published by Johns Hopkins University Press.

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