A Varied Diet Could Lead to Health Problems, Research Suggests

The advice that a varied diet is a healthy one risks encouraging people to eat unhealthy foods, raising their chances of disease, experts have warned.

The American Heart Association (AHA) arrived at this conclusion following a review of scientific literature published between January 2000 and December 2017. The resulting advisory was published in the journal American Heart Association journal Circulation.

Researchers concluded there is no evidence to suggest eating a varied diet helps an individual maintain a healthy weight or consume the most beneficial foods.

But the meta-analysis did link eating a wider variety of food with a delay in satiation, which could lead an individual to eat more. Limited evidence backed the idea that a diverse diet makes individuals eat more calories, adopt unhealthy eating behaviors or gain weight.

Is the evidence regarding low-carb and high-carb diets really that contradictory? Getty Images

Dr. Marcia C. de Oliveira Otto, lead author of the statement published in the American Heart Association journal Circulation, commented in a statement: "Eating a more diverse diet might be associated with eating a greater variety of both healthy and unhealthy foods."

"Combined, such an eating pattern may lead to increased food consumption and obesity," said Otto, who is assistant professor of epidemiology, human genetics and environmental science at The University of Texas Health Science Center at Houston.

For decades, health officials, including those in the U.S., have recommended the public eat a variety of foods. For instance, the current Centers for Disease Control and Prevention Dietary Guidelines for Americans suggests a diet should center around fruits, vegetables, whole grains and fat-free or low-fat milk and milk products; supplemented with lean meats, poultry, fish, beans, eggs, and nuts with the occasional consumption of saturated fats, trans fats, cholesterol, salt and added sugars.

Commenting generally on the advice to eat a variety of foods, Otto said: "There is little consensus about what so-called dietary diversity is, how it is measured and whether it is a healthy dietary goal."

Read more: Drinking This Much Coffee Could Help Keep Your Heart Healthy, Study Suggests

Better advice, the authors of the statement argued, would be to eat more plant-based foods like fruits, whole grains, vegetables and beans, as well as low-fat dairy products, non-tropical vegetable oils, nuts, poultry and fish. Foods like red meat, sweets and sugary drinks should be minimized, they said. It would be wise to follow The American Heart Association and the Dietary Recommendations or The Dietary Approaches to Stop Hypertension (DASH) diets.

"Selecting a range of healthy foods, which fits one's budget or taste, and sticking with them, is potentially better at helping people maintain a healthy weight than choosing a greater range of foods that may include less healthy items such as donuts, chips, fries and cheeseburgers, even in moderation," said Otto.

Dr. Amanda Squire, qualified dietitian at Cardiff Metropolitan University, U.K. and spokesperson for the British Dietetic Association, told Newsweek healthcare professionals should remember the importance of framing health messages as specifically as possible.

The take home message for the general public, she said, is "to make sensible choices and look at the frequency of high sugar, fat and salt containing foods. Everyone should take greater care to balance a treat food with a lot more healthier options and to reduce the intake of these treat foods to an occasional treat rather than a daily staple."

Tracy Parker, senior dietitian at the British Heart Foundation, agreed. She told Newsweek: "It's true that eating a variety of foods doesn't necessarily mean you are eating a healthy diet. If you're choosing a range of unhealthy foods, such as processed meats, cakes or sugary drinks, you're not giving your body what it needs."

This article has been updated with comment from Dr. Amanda Squire and Tracy Parker.