Evidence for 5 a day

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 USA had the 5-a-day campaign, which was softened to "Fruit and Veggies - More Matters" in 2007, although the 2015-2020 guidelines for Americans suggests 2 1/2 servings of vegetables and 2 servings of fruit per day.

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

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

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

These guidelines are based on nutrition research into overall mortality, and 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 (Circulation 2021;143:00-00. doi:10.1161/circulationaha.120.048996)

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 half-cup of fruits and vegetables (separately) from never to over 6 times per 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) per day, so the authors grouped intake into five 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 two 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 passed away 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.

When the authors compared the lowest level of combined fruits and vegetables intake with each increasing quintile of intake - up to 7.3 servings per 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 per day. Consuming more then 5 servings of fruits and vegetables per 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 per day, the greatest reduction in risk of death - again about 12% - was at 1.8 servings of fruit per day.

The reference level for vegetables in this study was higher, at 1.4 servings per day, but just 3.6 servings per 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 this means for you

Remember the phrase, "on average." If you're getting enough fruits and vegetables, whole grains, etc., most days per 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, and they'll fill you up - and you're likely to live longer.

First posted: March 24, 2021