Nutritional Pearls: Evidence For 5 a Day

Answer: Improving your consumption of fruits and vegetables can help you live longer. 

Your mother probably told you to eat your vegetables, and she was right.

The question many people have, however, is "Just how much?" In the 1990's the United States had the “5-A-Day Campaign,” which was softened to "Fruit and Veggies—More Matters" in 2007, although the 2015 to 2020 guidelines for Americans suggests 2 1/2 servings of vegetables and 2 servings of fruit a day.

Other countries have different guidelines: the National Health Service of England recommends 5 servings of fruits and vegetables a day, while Denmark prefers 6 servings a day, and the Australians 8 1/2 servings a day.

Most guidelines for the Mediterranean Diet recommend that women consume, on average, 9 ounces of vegetables a day and about 11 ounces a day for men. That's a little over a cup of vegetables a day for women and  almost 1 1/2 cups a day for men. That's one good-sized side salad, 2 large carrots, or 1 1/4 cups of broccoli.

Fruits and nuts are grouped together in the Mediterranean Diet and the guideline is for 8 ounces of fruits or nuts a day on average for women and 9 ounces a day for men. Again, that's about 1 cup a day, which is as little as 1 large apple, 2 bananas, or a couple handfuls of nuts.

The Research

These guidelines are based on nutrition research into overall mortality. In general, this type of research tends to treat fruits and vegetables as interchangeable, and the classification does not include nuts. Sometimes that classification includes grains or legumes such as corn or peas as well as fruit juices and potatoes, although sometimes it does not.

In another analysis of data acquired for the Nurses' Health Study and the Health Professionals' Follow-up Study (long-term, large-scale prospective studies of female nurses and male physicians, respectively), the authors of today's paper teased out the relative risk of death from any cause, as well as specific causes, based on the participant's intake of fruits or vegetables.¹

For their analysis the researchers excluded those diagnosed with diabetes, heart disease, or cancer, leaving a total number of participants at over 108,000 people. As part of the cohort studies, the participants responded to dietary questionnaires at least every 4 years, estimating their average yearly intake of a standard 1/2 cup of fruits and vegetables (separately) from never to over 6 times a day.

The authors chose to exclude from consideration such foods as tofu or soybeans, French fries, whole or mashed potatoes, juices, and foods consumed in small amounts such as garlic, mushrooms, or vegetable sauces, like chili sauces.

The vast majority of participants consumed at least 2 servings of fruits and vegetables (assessed together) a day, so the authors grouped intake into 5 increasing levels, with 2.1 servings as the comparison point.

In a similar way, they found that most people consumed at least 0.4 servings of fruits and 1.4 servings of vegetables. Accordingly, the 2 categories use those amounts as the comparison point, with total intakes ranged across 5 increasing levels of consumption.

Thus, the authors compared the fruit and vegetable intakes of those who died over the course of the study with those who did not.

You might expect that more fruits and vegetables, or either food group alone, would mean lower risk of death, with the highest levels of consumption being the most protective.

Not so.

The Results

When the authors compared the lowest level of combined fruits and vegetables intake with each increasing quintile of intake––up to 7.3 servings a day at the highest level––they found that the greatest reduction in risk of death––about 12%––was at just a little over 5 servings a day. Consuming more than 5 servings of fruits and vegetables a day didn't appear to be any more protective.

For fruits alone, compared to the lowest level of customary intake at just under 1/2 serving of fruit a day, the greatest reduction in risk of death––again about 12%––was at 1.8 servings of fruit a day.

The reference level for vegetables in this study was higher, at 1.4 servings a day, but just 3.6 servings a day was the most protective, with a comparatively small, reduced risk of just 6%.

Separate analyses of starchy vegetables such as corn, peas, or potatoes showed no association with a lower risk of mortality.

What’s the Take Home?

One of the things I like to emphasize to my patients is that you don't have to consume a perfect diet every single day. Remember the phrase, "on average." If you're getting enough fruits and vegetables, whole grains, etc., most days a week, you're probably doing just fine.

This study is particularly helpful because it shows that improving your consumption of fruits and vegetables just a little bit can have a significant impact on your health. Snack on a piece of fruit every day. Have an extra helping of a vegetable side at dinner and load your sandwich with lettuce, spinach, sprouts, grated carrots, tomatoes, avocado, or leftover roasted vegetables. They're tasty, low in calories, they'll fill you up, and you're likely to live longer.

Reference:

1. Wang DD, Li Y, Bhupathiraju SN, et al. Fruit and vegetable intake and mortality: results from 2 prospective cohort studies of US men and women and a meta-analysis of 26 cohort studies. Circulation. 2021;143(17):1642-1654. https://doi.org/10.1161/circulationaha.120.048996

Dr. Gourmet is the definitive health and nutrition web resource for both physicians and patients with evidence-based resources including special diets for warfarin users, patients with GERD/acid reflux, celiac disease, type 2 diabetes, low-sodium diets (1500 mg/d), and lactose intolerance.

Timothy S. Harlan, MD, is a board-certified internist and professional chef who translates the Mediterranean diet for the American kitchen with familiar, healthy recipes. He is an assistant dean for clinical services, executive director of The Goldring Center for Culinary Medicine, associate professor of medicine at Tulane University in New Orleans, and faculty chair of the Certified Culinary Medicine Specialist program.