by Marion Nestle
Aug 8 2010

Why public health matters

I received a couple of requests to define “public health” last week from readers Anthro and MA.  As MA puts it,

Maybe…we need a definition of “public health.”  I view my health as a private matter, my food choices as a private matter, and an expression of my freedom.  To me, public health is not an individual concern, it’s a corporate (group) concern – government, schools, companies, farms, etc.  Public health includes things like properly working sewer systems, sanitation, water quality, and air quality.   Marion – can we get a definition of ‘public health’ from you, as Anthro suggested?

My definition of public health isn’t much different from mainstream definitions.  But to me, public health is a critically important expression of democracy, and the antithesis of  a “corporate” concern.  Public health approaches promote good health for everyone, not just those who can afford it or are educated enough to make appropriate choices.

A standard definition such as the one given in Wikipedia, says that public health is about promoting health and preventing disease through societal choices and efforts.   Public health deals with health at the population level, rather than at the level of individual personal responsibility, and it emphasizes prevention rather than treatment.

In my experience teaching public health nutrition, the concept of public health is sometimes hard for people to grasp, especially since populations are made up of individuals. I like to explain it this way: public health makes it easier for individuals to make healthful food choices for themselves and their families. Or to put it another way, public health makes better food choices the default.

The classic example of a public health intervention is water chlorination.  As individuals, we could all boil our own drinking water to kill harmful organisms but this requires us to have stoves, pots, and fuel, and to know how to boil water.  For many people, having to do this would be an intolerable burden and responsibility.  Instead, some societies choose to take public health measures to ensure that drinking water is safe at the tap for everyone.

Other food examples: milk Pasteurization, banning of trans fats, food labeling.

The particular example that elicited the question has to do with food safety.   We, as a society, could insist that food producers take measures to ensure that their products are free of harmful microorganisms (public health), or we could teach individuals how to manage food safety in the home or restaurants and cook foods properly (personal responsibility).

Preventing obesity is another example: We could, as a society, take measures to make it easier for people to eat more healthfully and be more active (public health) or leave it up to individuals to do this for themselves (personal responsibility). Many of the arguments about suggested public health measures to prevent obesity are about how best to balance society’s needs with individual rights.  But as I see it, the proposals aim to tweak societal choices that have already been made: which crops receive farm subsidies, for example.

An exceptionally clear example is how to avoid toxic levels of methylmercury in fish.   We can teach pregnant women to recognize which fish are high in methylmercury and hope this works well enough so they will avoid buying such fish (personal responsibility) or we could–as a society–require coal-burning power plants to scrub their emissions so mercury doesn’t get into ocean or lake waters in the first place (public health).

Obviously, both public health and individual approaches are necessary, but the overall objective of public health is to make it much, much easier for individuals to make better health choices without having to think about them.

Because public health applies to everyone, it is essentially democratic.   And that’s one of the reasons why I think it matters so much.

  • Pete

    Roxanne – I agree with you that the meat in the US is substandard, but not because it’s “fat heavy” There’s nothing wrong with fat, even saturated fat, if there were it wouldn’t be the main component in breast milk – the perfect food. The antibiotics and hormones however are another story. Many small meat producers feed their cattle flax seed in addition to grazing to make the meat a bit more marbled. It also adds some omega 3 fats which doesn’t hurt. You should check out the link Uncle H provided in his next to last post.

    Also, after I myself lost 125lbs of fat eating in more of a paleo fashion I have advised numerous individuals on meeting thier personal weight loss goals. While I admit there are certainly the carb tolerant among us, in my experience about 70% do NOT fall into that category. And the ones that do ALSO benefit from this type of grain restricted diet.

    Oh and I never mentioned whole soy – just the isolate that seems to be gaining in popularity as an ingredient in processed low carb products.

  • I’ve seen Stephen’s blog. In fact I stumbled across it when I first heard about paleo-diets. I’m just going to put it simply. The thread I read drove me up the wall. He takes archaeological speculation as fact and cites certain dig sites and holds them up as if anthropologists have found a prehistoric cookbook.

    I visited his blog just now. The first post? A claim that a single study done in Japan shows that saturated fat has not been linked to CVD. In a much broader review of data, the DGAC found a strong connection between SFA intake and an increased risk of CVD. Stephen seems to pick and choose evidence that supports his views. In this case, Japanese research which probably involved a different balance of SFAs then the ones found in American diets.

    Amusingly, I studied in the department where one of Stephen’s favorite anthropologists is a faculty member. Dr. Cohen’s theories on the association between a shift from hunter-gatherer towards agriculture and the rise of diseases and malnutrition are interesting. However, they are not the endpoint of research. Malnutrition and disease and can also easily be attributed to population densities, problems with food storage, etc., all associated with a shift to a sedentary lifestyle.

    Additionally, we do not know the parasitic, bacterial, or viral make-up of our ancestors’ environments. Dr. Cohen’s work is important because it challenged the concept that societies have been on a constant, rising path of improvement. To single out the ancient diet as the primary factor leading to the rise in illnesses is taking too narrow a view. I believe it was the process of transition, not the direction that caused such problems.

    I still can’t help but wonder what the attraction to the idea that research conducted on a much broader segment of the population in the present is less valid than the research conducted on a much smaller sample of human remains.

  • Uncle Herniation

    Roxanne – right now, we know that Twinkies are not good for us, and if we ate an all-Twinkie diet, many of us would be very sick. However, some of us would likely do better than others on the all-Twinkie diet. Those of us who were able to reproduce on this diet would increase the percentage of people in future generations capable of living only on Twinkies. If Twinkies are the primary food source for the next 20 million years, humans at that future time will probably have adapted to eating Twinkies and be much more healthy relative to today’s Twinkie eaters. Same goes for meat or any other food. Whether ancient humans were “healthy” does not necessarily mean that the foods they ate are bad for us now. We have probably evolved to tolerate certain foods better than they were tolerated in the past.


    Did you also notice Stephan’s recent post on saturated fats included a link to this study?

    You say “I still can’t help but wonder what the attraction to the idea that research conducted on a much broader segment of the population in the present is less valid than the research conducted on a much smaller sample of human remains.” Do you dismiss the results of this meta-analysis, which included data from 347,747 participants? If you don’t accept these findings and you don’t accept anthropological data, how do you choose which science to believe? Are you also picking and choosing findings that support your views? Is this DGAC study published? If so, I’d appreciate a link, and your rationale as to why it’s more valid than the AJCN meta-analysis.

  • Roxanne Rieske

    Uncle Herniation: Sorry, the “logic” you used to make your twinkie analogy doesn’t make any sense me me.

  • The DGAC is the Dietary Guidelines Advisory Committee, and I am referring to the 2010 report. It can be found here:

    Try Part D, Section 3, Question 1. It is a review of 12 studies done since 2004 and contained data on hundreds of thousands of individuals as well. Further, it focused on studies regarding an “American diet”, i.e., burgers not sushi.

  • Uncle Herniation


  • Uncle Herniation

    Oops, sorry!

    Roxanne, the same principle would apply to any selective pressure that shapes evolution. For example, people of European descent have more lactase persistence than African and Asian persons. This likely evolved as people living in northern climates relied upon dairy products during winter. The first humans to live in northern Europe probably had symptoms of lactose intolerance when they first began to rely upon milk. Those who tolerated milk well enough to survive to reproduce passed down their lactose-tolerating genes; those who could not tolerate milk may have died before they could reproduce. Because they had to rely on milk doesn’t mean they were healthy – their reliance on milk might have caused very poor health. But that doesn’t mean that now, in present time, milk is unhealthy for everyone.


    Do you dismiss the results of this meta-analysis, which included data from 347,747 participants? If you don’t accept these findings and you don’t accept anthropological data, how do you choose which science to believe? Are you also picking and choosing findings that support your views? What is your rationale as to why the DGAC report is more valid than the AJCN meta-analysis?

  • For one, the DGAC isn’t paid for by the National Dairy Council, a major contributor to our intake of saturated fat. It’s in their interests to select and edit conclusions to favor SFA not being a part of CVD.

    I’d tend to trust a committee of respected professionals who are not being employed to find a favorable outcome for any entity other than the public. The 2010 DGAC reviewed data regarding SFA for only the last six years. Add that to years of research that have led us to understand the role of SFA in CVD, and you have a more convincing argument that an industry supported meta-analysis. The size of the research that has led the medical and nutritional field to recognize that SFA increases the prevalence of CVD in the public is much larger than a 300,000+ meta-analysis. (This is not to mention that 2010 DGAC conclusions were based on a 300,000+ sample size as well).

    I don’t so much pick and choose as I try to weed. I have no vested interest in whether or not SFA is to blame. I like milk. I like a well-marbled steak. I like human beings more, and I don’t want them to have heart attacks.

  • Uncle Herniation

    Yes, it’s great to be skeptical when funding sources could lead to conflicts of interest. But as a meta-analysis, this study pooled previously published results. It’s hard to argue that the authors were biased when the actual data came from other studies. They simply analyzed these data. You could do the same if you wanted to go back and look through the articles and do the math. You may disagree with the studies they chose to include or their analytic methods, but they can’t hide anything, and therefore if the results are incorrect or biased, you could decide for yourself by going back to the original sources. Both large meta-analytic studies are worthy of our consideration. Seems silly to dismiss one out of hand.

    I also don’t want people to have heart attacks. If you’re worried that saturated fat is to blame, you’d better find a way to get your body to store extra energy as something other than fat. Do you find it peculiar that the body would store its extra fuel in a form that is most likely to cause heart attacks? Is it logical to think that every time you burn any of your body fat, you’re increasing your risk of having a heart attack?

  • Marion — really liked your insightful commentary. It’s nice to be read a positive perspective on public health in the midst of heated political banter.