When it comes to the search for the fountain of youth, it seems most people assume the answer lies in food. From green smoothies to coconut oil in your coffee, new food solutions for staying healthy, fit, and young have been such a hot topic in the media that you may be shocked to learn that most of these things make little difference when it comes to aging well.
Don't get me wrong: What you consume is terribly important, but it's not because drinking green tea instead of coffee will cause you to live longer.
Here's why: To figure out how a specific food affects our bodies over time, we have to take into consideration all of the other lifestyle behaviors influencing our health simultaneously over a long period of time. And if you already realized it, the people who "eat well" tend to be the same people who engage in other healthy behaviors. So, how can we figure out whether the organic broccoli that you ate this week was more important to your living and staying healthy until 100 than the Zumba class you took? We can’t—and we won't. (Besides, almost certainly both were useful.)
Nutrition scientists usually focus on how certain diets (not particular foods per se) compare to others and attempt to evaluate "the best" ones. But very few studies about nutrition are able to show significant effects on the overall aging process once taking into consideration things like how much people exercise, how much sleep they get, their mental health, and so on. Although some have declared certainty about the best diet based on large cross-sectional studies about nutrition (specifically, the China Study), in the end, those studies provide trends in health outcomes in groups of people who share similar diets and other lifestyle behaviors. It’s not possible to make a causal connection between specific foods or diets and specific health outcomes with such correlational data.
But there are some good studies out there that do give us insight about nutrition and some guidance about what to eat. Here’s one that’s notable: The National Institute on Aging funded one of the most valuable studies for examining lifestyle factors, including diet, that increase our ability to live a long, healthy life. The InCHIANTI studies began in 1998 with participants located in the Chianti region of Italy. Unlike many other studies on health and aging, these researchers collected very detailed information, including a range of biomarkers, on a relatively large number of people, and have collected data at regular intervals over time.
What have they discovered? Lots of things, but a few that are particularly noteworthy when it comes to nutrition and aging. Like others (1), they have showed that adherence to the Mediterranean diet is related to superior outcomes relative to other diets (2). But the most compelling result from the research may explain the value of the Mediterranean diet—that better health and longevity is strongly associated with maintaining high carotenoid levels (3,4). Carotenoids are a blood-level indicator of fruit and vegetable consumption. The higher one’s carotenoid levels, the better that individual maintains her health, and the lower her risk of mortality. Further, the benefits associated with high carotenoid levels are on par (though not quite as significant) as regular exercise (4,5). While other studies have shown a positive relationship between fruits and vegetables and health, this one shows that, independent of any other dietary factors, long-term fruit and vegetable consumption, regardless of the other foods being consumed, impacts the aging process in a profound way.
And what about all the other studies out there? Prospective, case control, longitudinal studies are the only way to learn the effects of long-term lifestyle behaviors and aging. But these are terribly expensive, and in order to figure out what is worth spending the money and time to study, we first need to know some basic relationships—for example, why embark on a large study about the benefits of green tea if people who drink green tea don’t seem to have significantly better health than anyone else? And yet the media is sprinkled with reports based on these kinds of studies, making claims of benefits for one food or another, which are then countered by other studies that show an opposite effect only months later. These kinds of studies get lots of attention. They do help people at least pay more attention to nutrition, and they can help scientists make significant incremental discoveries. But they have limitations and are not designed to provide prescriptive advice. Remember when we used to think that margarine was better for us than butter?
When some people hear a finding from one study, and the opposite finding from another, they may either choose to believe the more convenient outcome ("I like coffee so I'm going to assume that the study that shows drinking lots of coffee is accurate") or throw up their arms and assume that none of it matters.
Neither is a good choice.
We don't yet know, for example, whether broccoli or Brussels sprouts have a more potent benefit to our health and longevity, but we do know enough about lifestyle behaviors to make better decisions than most of us are currently making when it comes to nutrition. In fact, if everyone did the one thing we know for certain with regard to nutrition, the health of our entire nation would be remarkably different.
What we KNOW you should do:
Eat more fruits and vegetables. The recommendation is 9 servings of fruits and vegetables (at least 5 of which are vegetables) each day. A serving is a half-cup. Is 9 enough? What about 6? Should it be steamed or raw? Green or orange? It may be years before we know for certain what the perfect number and mix of fruits and vegetables is if we want to get the biggest bang for our buck, so to speak, but there doesn't seem to be any harm in eating too many vegetables unless you're just eating one type and nothing else. Here's a good way to pick: Do you like it? Eat it. Try vegetables and fruits you've never tried. If you don’t like vegetables, figure out a way to like them. Cook them differently. Ask people for recipes. The more variability, the more different types of good things you'll get. Only a sliver of us eat anywhere near 9 servings a day on a regular basis, and it's really the only thing we know for sure when it comes to nutrition and long-term health outcomes.
What you SHOULDN'T do:
Eating foods that cause you to gain lots of weight is bad. Eating foods that cause your blood pressure to be too high is bad. Eating foods that have lots of sugar so that your blood tests indicate diabetes or pre-diabetes is bad. Which foods are these for YOU? Who knows? We're all different, so pay attention to how what you eat influences how you feel and how your body responds. But keep in mind, there are long-lived, very healthy people all over the world with lots of different types of diets, but in none of those groups of people do they eat mostly stuff that comes in a box, a can, a wrapper, or something you can get at a drive-through window. Besides, if you’re eating 9 fruits and vegetables a day, you won’t have enough appetite left to eat junk.
Lifestyle is the medicine of the future, and the big task for nutrition research moving forward is figuring out the doses to maximize the best outcomes. In the meantime, eat more fruits and vegetables, exercise more, and do things that make you happy. You'll be better off than searching the internet for information about whether to cook your eggs in coconut oil or butter.
(1) Knoops K, de Groot L, Kromhout D, Perrin AE, Moreiras-Varela O, Menotti A, van Ataveren WA. Mediterranean diet, lifestyle factors, and 10-year mortality in elderly European men and women: the hale project. JAMA. 2004; 292(12): 1433-1439. Doi:10.1001/jama.292.12.1433.
(2) Milaneschi Y, Bandinelli S, Corsi AM, et al. Mediterranean diet and mobility decline in older persons. Exp Gerontol 2011;46:303-308. Doi: 10.1016/j.exger.2010.11.030.
(3) Laurentani F, Semba RD, Bandinelli S, Dayhoff-Brannigan M, Laurentan F, Corsi AM, Guralnik JM, Ferrucci L. Carotenoids as protection against disability in older persons. Rejuvenation Research. 2008, 11(3); 557-563. Doi:10.1089/rej.2007.0581.
(4) Laurentani Fl, Semba RD, Dayhoff-Brannigan M, Corsi AM, Di Iorio A, Buiatti E, Bandinelli S, Guralnik JM, Ferrucci L. Low total plasma carotenoids are independent predictors of mortality among older persons: the InCHIANTI study. Eur J Nutr. 2008; 47; 335-340. Doi:10.1007/s00394-008-0732-9.
(5) Nicklett EJ, Semba RD, Xue Q, Tian J, Sun K, Cappola AR, Simonsick EM, Ferrucci L, Fried LP. Fruit and vegetable intake, physical activity, and mortality in older community-dwelling women. J Amer Ger Soc. 2012; 60(5): 862-868. Doi:10.1111/j.1532-5415.2012.03924.x