Harvard's aging study's dark surprise
And a color-coded food & beverage chart showing the best and worst longevity foods.
On Monday, Harvard’s School of Public Health announced new research that reveals — are you sitting down? — that healthy eating in midlife is linked to healthy aging.
Yes. Several media sites ran with this mind-blowing news while failing, in a stark example of how rote health journalism is nowadays, to notice the disturbingly unhealthy aging revelations that lay further down in the researcher’s findings.
What the new Harvard research says
Before I get to those, some quick context:
In a paper published in Nature Medicine, 13 researchers from Harvard and the universities of Montréal and Copenhagen concluded that people who maintain diets that includes more plant-rich foods have a greater chance of living into their 70s than people who eat more ultra-processed foods and red meat.
The research does include several genuinely interesting insights into the diets, and specific foods and beverages, that it associated with greater or lesser chances of remaining healthy after 70. (See chart below for more detail on those foods.)
The study examined data from 105,000 Americans, aged 39 to 69 (two-thirds women and ~95% white) who self-reported detailed dietary consumption every 4 years over the course of 30 years, from 1986 to 2016. This is a significant longitudinal data set, spanning decades, though one lacking demographic variety.
Researchers categorized participants’ self-reported eating and drinking regimens into eight healthy dietary regimens that included large amounts of fruits, vegetables, whole grains, unsaturated fats, nuts and legumes. All the dietary regimes, except for the vegetarian diet, also included meat, fish and certain amounts of ultra-processed food and red meat.
The dietary regime that was most greatly associated with “healthy aging,” which the study defined as reaching age 70 with no cognitive, mental or physical problems or chronic disease, was the Alternative Healthy Eating Index (AHEI).
The strictly vegetarian diet had the weakest association with “healthy aging.”
Also: All 105k study participants were nurses and other health professionals.
For further details on the study, here’s a servicable Washington Post article.
What The Post, NBC News and the rest of the media missed
So here’s the dark surprise in this Harvard study that hasn’t been reported elsewhere, as far as I can tell: Though this research purports to show which dietary regimen promotes healthy aging, the vast majority of this massive cohort of 105,000 health professionals did not age well and, in fact, hit age 70 in demonstrably poor health (see screenshot below):
Only 9.3% made it to 70 with “intact” cognitive, mental and physical function and no chronic diseases. (There’s a pronounced gender gap: though 11% of women in the study hit 70 in all-around good health; only 6% of men did.)
Only 38% — barely a third — managed to survive to 70
Fewer than 1 out of 4 managed to avoid contracting a chronic disease
Only a third reached 70 with full cognitive function; fewer than a third had “intact physical function”
Only about 1 in 4 study participants had a clean bill of mental health by 70
Here’s the upshot:
A study of a huge number of healthcare professionals from the 1980s, 1990s, 2000s and 2010s who ate mostly plant-based diets reveals that few of them made to 70 in good health. Nearly two-thirds didn’t even make it 70, though cohort life expectancy1 for men and women of that generation was 73 and 79, respectively. Maybe healthcare workers are more likely to be unhealthy (due to stress and compensatory behaviors like smoking and drinking, say, or to exposure to illnesses). The published study is silent that topic.
But consider the implications: If the contemporary average life expectancy2 for a white American woman and man is 80 and 75, respectively (the study participants were overwhelmingly white), is it reasonable to assume that most Americans still breathing at 70 are not, and will not be in the future, in particularly good health?
AUTHOR’S EDIT: As an AGING with STRENGTH reader pointed out after this article first published, mine may be an “apples to oranges” comparison, because life expectancy for white American women and men between 1947 (when the oldest people in this study would have been born) and today has increased by 14% and 17%, respectively. However, what is known as “cohort life expectancy,” explained in Footnote 1 below, shows that these 105,000 health professionals would have a life expectancy well above 70 years. Moreover, two-thirds of the people in this study cohort were women, who, if you believe the Social Security Administration’s life tables, would have had a life expectancy of 78.
What do these numbers say about the prospects of people now in midlife reaching, or living beyond, the rather young age of 70 without a chronic disease or significant cognitive, emotional and physical problems? During the ~75 years since many of the people in this study were born, American obesity rates for white men and women have exploded at least 4x, from under 10% at mid-century to 38% today. These rates, as well as those for severe obesity, have gotten only worse since 2016, when the data for this study concluded.
A “healthy aging” food and beverage chart worth reading
The Harvard study also includes a chart (see below) of foods and beverages that illustrates the associations between individual dietary factors and the researchers’ definition of “healthy aging.”
Some of this information is intuitive. For instance, larger consumption of fruits, whole grains, vegetables, added unsaturated fats, nuts, legumes and low-fat dairy were associated with greater odds of healthy aging. Likewise, greater consumption of trans fats, sodium, total meats, including red and processed meats, were associated with lower odds. But then there are some counterintuitive results as well.
Below the chart is a simple explanation of how to read it.
Interpreting the chart’s colors
Green squares show foods that are good for healthy aging — they increase your odds of aging well. Pink/red squares show foods that are bad for healthy aging — they decrease your odds of aging well. Darker colors (either green or pink) mean stronger effects. Lighter colors mean weaker effects. White/blank spaces mean no significant relationship was found. Asterisks (*) indicate findings that are statistically significant.
The chart’s main takeaways
This chart suggests that a primarily plant-based diet with moderate amounts of select animal products (like fish and low-fat dairy), healthy fats and minimal processed foods, red meat and added sugar would provide the best chance for healthy aging.
Several other findings that may strike you as either interesting, affirming, counterintuitive or utter crapspackle:
Fast food is…sorta healthy? There are several possible explanations why the "Fast and fried foods" row in this chart are green. The study’s authors suggest that people who occasionally eat out might have stronger social connections, which are known to positively influence longevity and health.
Eggs show mixed effects. Eggs appear to have a neutral to slightly positive effect on physical function and mental health, despite years of concern about their cholesterol content. This aligns with more recent research suggesting eggs may be healthier than previously thought.
Coffee has varied effects. Coffee shows a negative association with cognitive function but positive associations with mental health and survival to 70 years of age. This mixed pattern might explain conflicting findings about coffee in previous research.
Pizza shows some positive associations. Similar to fast foods, pizza has some green squares (particularly for healthy aging overall), which seems counterintuitive for what's often considered an unhealthy food.
Potatoes have mixed effects. Potatoes show negative associations with some aspects of healthy aging but positive associations with others, despite often being grouped with other vegetables.
Snacks have positive associations. The "Snacks" category shows several green associations, particularly with survival to age 70 — unexpected for what most people would consider less healthy foods.
Dietary pattern effects were stronger in women. The study found that the associations between dietary patterns and healthy aging were consistently stronger in women than in men.
Stronger benefits in higher-risk groups. Dietary patterns showed stronger associations with healthy aging among smokers, overweight individuals, and those with lower physical activity levels, suggesting diet may have more impact in higher-risk populations.
Dairy products show mixed effects. Low-fat dairy shows positive associations while high-fat dairy (including butter) shows negative associations, reinforcing the importance of distinguishing between different types of the same food group.
Participants in the highest quintile for the the following diets — the Alternative Healthy Eating Index (AHEI); the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND); the healthful plant-based diet(hPDI); and the Planetary Health Diet Index (PHDI) — consumed more alcohol than those in the highest quintile for the Dietary Approaches to Stop Hypertension (DASH) and Alternative Mediterranean Index (aMED).
Altogether, the research highlights the complexity of nutrition research and reinforce that the relationships between foods and health outcomes aren't always as straightforward as commonly believed.
Building nutritional strength for yourself: pick and choose
The study authors said their findings, and this chart, are best used not as a set of rigid rules but as guidance that people can use to build a dietary plan that fits their specific goals. I plan to reach out to them, to follow up on the “dark surprise” statistics surrounding the paucity of participants who managed to get to 70 in good health.
I’ll let you know what the researchers tell me, if they respond. But let’s also keep sight of the practical wisdom here.
As Anne-Julie Tessier, an assistant professor of nutrition at the University of Montréal and the lead author of this study told the WaPo: “This suggests what you eat in midlife can play a big role in how well you age.”
Let’s hope so. But if the low “healthy aging” success rate indicated in this research is accurate, just getting to 70 clinically “intact” may be a bigger challenge, with a lower likelihood, than any of us had thought.
What are your expectations for “healthy aging”? Leave a comment.
Life expectancy is calculated using a tool called a life table, which shows, for each age, what the probability is that a person will die before his or her next birthday.
There are two different types of life table: cohort and period. The cohort life table takes into account observed and projected improvements in mortality for the cohort throughout its lifetime. Cohort figures are therefore regarded as a more appropriate measure of how long a person of a given age would be expected to live on average than the alternative measure, known as period life expectancy.
Period life expectancies use mortality rates from a single year (or group of years) and assume that those rates apply throughout the remainder of a person's life. This means that any future changes to mortality rates would not be taken into account.
My wife and I are almost 10 years into our n=2 study of eating a high-fat, low-carbohydrate lifestyle. The major changes made were to eliminate sugar as much as possible, stop consuming seed oils, and go for full-fat instead of low-fat whenever possible. Lots of grass-fed beef as well. We fall exactly into the age range of this study. At 77 and 78 we are the healthiest we've ever been. However it's not all about the diet. Every morning we walk 5k (3.1 miles) before doing anything else. We have none of the usual problems of old people, and have only one prescription between us for blood pressure. In the ages between 39 and 69 we were raising 3 kids, operating our own businesses, and eating the "Standard American Diet" with all its processed food miseries. If you make it to 70, it's not too late to fix the damage done.
I think you might be misunderstanding the study’s findings. These people were born in or around 1947, so the relevant life expectancy measure is life expectancy at birth (LEB) in 1947. Using 2020 LEB measures is comparing apples to oranges, becuase the study participants were not born in 2020. The LEB for people born in 1947 in the US is approx. 65 and 70 years for men and women respectively. So a priori it is unsurprising that a majority of the study’s participants passed away before their 70th birthday.
Similarly, you need to interpret the healthy aging results conditional on having survived to the end of the study. For example, it is not accurate to claim that “two-thirds did not retain full cognitive function”—a majority of those two-thirds did not retain any cognitive function whatsoever because they were dead (again, as reasonably expected in accordance with relevant LEB measures). In reality, 89% of those who lived to the end of the study retained full cognitive function. The same applies to retaining intact physical function (74% did), being free of chronic diseases (60%) and maintaining intact mental health (70%).