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(CNN) — What does it take to reach age 70 and not have any chronic diseases?

A team of researchers led by scientists from the Harvard T.H. Chan School of Public Health sought to answer this question by following over 100,000 Americans in their 40s, 50s and 60s for up to three decades.

The results, published March 24 in the journal Nature Medicine, found that healthy diets earlier in life were associated with a higher likelihood of healthy aging, even after accounting for other lifestyle factors, such as physical activity and smoking status.

I wanted to better understand which diets could lead to higher odds of healthy aging. How might these study findings affect people’s nutrition choices during midlife and other periods in their lives?

To learn more, I spoke with CNN wellness expert Dr. Leana Wen. Wen is an emergency physician and adjunct associate professor at George Washington University. She previously served as Baltimore’s health commissioner.

CNN: How long did researchers spend looking at people’s eating habits? What did they learn?

Dr. Leana Wen: This is a longitudinal observational study, meaning that researchers followed the same group over time and studied self-reported habits and health outcomes. Researchers asked study participants for their nutrition habits over up to three decades, until they reached age 70. Participants regularly and extensively documented their food consumption, reporting how often they ate more than 130 different foods.

The study team then classified the food consumption by measuring how close the consumption pattern was to eight types of healthy diets and to the consumption of unhealthy ultraprocessed food.

At the end of the study period three decades later, researchers found that 9,771 out of 105,015 participants, or about 9.3%, achieved what they defined as healthy aging, which is living to 70 years of age free of chronic diseases such as diabetes, hypertension and heart disease, and not having cognitive, physical or mental health impairments. The study team found that for each of the eight healthy diets, higher adherence was associated with greater likelihood of healthy aging.

In addition, the researchers found that higher consumption of fruits, vegetables, whole grains, nuts, legumes, unsaturated fats and low-fat dairy products was linked with greater odds of healthy aging. On the other hand, higher consumption of trans fats, sodium, sugary beverages, and red or processed meats was associated with lower odds of healthy aging.

In my view, this was a sound study that demonstrates quite convincingly that following a healthy diet earlier in life is a key factor involved in healthy aging. This research is consistent with other studies that have found people can gain years in life expectancy by eating more vegetables, fruits, whole grains and nuts and avoiding sugary drinks and processed food.

CNN: What are the eight types of diets that were included in this study?

Wen: The study participants did not self-identify that they were following a particular diet. They reported their food consumption, and researchers correlated their long-term adherence to dietary patterns that are considered to be healthy.

The eight diets were the Alternative Healthy Eating Index (AHEI), the Alternative Mediterranean Index (aMED), the Dietary Approaches to Stop Hypertension (DASH), the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND), the healthful plant-based diet (hPDI), the Planetary Health Diet Index (PHDI), the empirically inflammatory dietary pattern (EDIP), and the empirical dietary index for hyperinsulinemia (EDIH).

These diet patterns share numerous commonalities. For instance, aMED and MIND are based on the Mediterranean diet, rich in plant-based foods, lean proteins and healthy fats. PHDI and hPDI maximize the consumption of fruits, vegetables, nuts and legumes. There are some differences — for example, DASH emphasizes reduced sodium, EDIP uses an inflammatory index for foods, and EDIH scores food by anticipated insulin secretion.

CNN: How could these results affect people’s nutrition choices during midlife?

Wen: These findings should prompt people to think about a nutritious diet as a key component of healthy aging. When making nutrition choices, everyone should aim for whole foods that are minimally processed, such as leafy green vegetables, fresh fruits and whole grains. This study and others consistently show the benefits of nuts as well as legumes, such as beans and lentils.

Fish and lean meat can also be part of a healthy diet. On the other hand, highly processed meats, such as deli cold cuts and fried chicken, are associated with worse health outcomes.

CNN: What about younger individuals? Do their diet habits matter?

Wen: This study examined dietary habits of people through their 40s, 50s and 60s. It didn’t look at nutrition habits earlier in life. But based on other studies, it’s reasonable to recommend that everyone, no matter their age, should aim for a healthy diet, while also keeping in mind that it’s never too late to start developing healthier habits.

CNN: It may be obvious, but what did the study suggest we should not be eating?

Wen: While much of the focus of the study is on types of diet and food that are positively associated with healthy aging, there are also items that are negatively associated. Notably, these include sugar-sweetened beverages, such as sodas and fruit drinks with added sugar, as well as ultraprocessed foods and items with high levels of sodium and trans fats.

Everyone can make a conscious effort to reduce their consumption of sodas, fruit drinks and other sugar-sweetened beverages. They can also try to cut their consumption of ultraprocessed food, which has been linked in numerous other studies to higher risk of mortality.

Looking at the packaging label is always a good way to assess whether the food may be ultraprocessed. If it has a long list of ingredients with many additives, the item is probably ultraprocessed and is best replaced with a similar food that has minimal processing. Labels can also provide information on levels of sodium and trans fats.

All this said, I think we must also acknowledge the role of policy in helping people to make nutrition choices. In many communities, ultraprocessed food is cheaper and more readily accessible than fresh fruits and vegetables.

Studies like this one can help make the case that optimizing people’s diets and helping them to access nutritious food can reduce chronic disease, which is essential to ensuring a healthy workforce and reducing health care costs down the line. Policymakers should look at the important role that food has in determining people’s well-being and help make the food environment one that is most conducive to long-term health.