Researchers at the U.S. Centers for Disease Control and Prevention (CDC) found that for every five percent increase in calories from ultra-processed foods, there is increased risk for heart attacks and strokes (presented at the American Heart Association’s Scientific Sessions in Philadelphia, November 16, 2019). Taking in 70 percent of calories from processed foods doubles heart attack risk factors, compared to eating 40 percent or less of calories from processed foods. The CDC used data from 13,446 participants who completed yearly questionnaires for five years (2011-2016) on foods eaten and their cardiovascular health. Foods were grouped by their amount of processing, with ultra-processed foods being those that are made entirely or mostly from substances extracted from foods, such as fats, starches and sugars, and additives such as artificial flavors, colors or emulsifiers. Data on cardiovascular health were collected based on AHA’s guidelines for healthful blood pressure, cholesterol and blood glucose levels, avoidance of tobacco products, good nutrition, healthy body weight and adequate physical activity.
Many earlier studies have also shown that processed foods are associated with increased risk for high blood pressure, high cholesterol, and some cancers. A study of 105,159 French adults followed for 10 years found that a 10 percent increase in processed foods was associated with a 12 percent increase in heart disease, a 13 percent increased risk for heart attacks, and an 11 percent increased risk for strokes, while an increase in unprocessed foods was associated with marked reduction in all of these diseases (Brit Med J, May 29, 2019). Another study in the same BMJ issue, of 19,899 Spanish university graduates followed for 15 years, showed that eating more than four servings per day of highly processed foods was associated with a 62 percent increased risk of death from any cause. For each additional daily serving of ultra-processed food, the death rate increased by 18 percent (BMJ, May 29, 2019).
Processed Foods and Obesity
Since 1980, the rate of obesity in North America has doubled, and the increase in ultra-processed foods appears to be a major cause (Annu Rev Public Health, 2014; 35: 83-103). Manufacturers of food products know that people will buy foods that look, taste and feel good, so they add lots of sugar, salt, artificial colorings, artificial flavorings and emulsifiers to their packaged foods. They often grind up the foods, particularly fruits (for juices and extracted sugars) or whole grains (to make flour), which markedly increases absorption and blood sugar levels to increase risk for weight gain and diabetes. They discard much or all of the beneficial fiber, and the perishable parts (such as wheat germ) that are rich sources of vitamins and other nutrients.
Reasons for the increase in processed foods include:
• They have longer shelf lives (less spoilage), so they can be sold at lower prices (Public Health Nutr, 2018; 21: 5-17).
• They taste better to many people because they have added sugars, fats and flavorings.
• They take less time and knowledge to prepare than fresh (unprocessed) foods.
• They are widely used in fast food restaurants, which have increasingly replaced home-prepared meals.
I recently reported on a study from the National Institutes of Health (NIH), which showed that eating a lot of ultra-processed foods caused people to eat more calories and gain more weight than when they ate a minimally processed diet containing the same number of calories (Cell Metab, Jul 2, 2019;30(1):67-77.e3).
• A diet high in ultra-processed foods contains more added sugar, which causes a high rise in blood sugar so your pancreas releases insulin that acts directly on your brain to make you hungry, so that you eat more food.
• Eating processed foods makes you eat faster so that you can eat more before your gut sends messages to your brain to tell you that you are full (Science, 2019; 363: 346-347). In the NIH study, subjects ate ultra-processed foods at an average rate of 37 grams and nearly 50 calories per minute. When they ate unprocessed foods, they ate an average 30 grams at 32 calories per minute.
• Ultra-processed foods are “Formulations of several ingredients which, besides salt, sugar, oils, and fats, include flavors, colors, sweeteners, emulsifiers and other additives used to imitate sensorial qualities of unprocessed or minimally processed foods, or to disguise undesirable qualities of the final product” (BMJ Open, March 9, 2016;6(3)). Ultra-processed foods include soft drinks, most dry breakfast cereals, frozen pizzas, frozen meals and entrees, breads, cakes, pies, cookies, snack bars including sports nutrition bars, diet bars and “energy” bars, candy, crackers, salty snack foods such as potato chips, corn chips and pretzels, processed meats including those made from poultry or seafood, instant soups and noodle bowls, bottled juices, salad dressings and many others.
• Minimally-processed foods are parts of plants or animals that have been factory-cleaned and packaged and may have been ground, chopped or otherwise reduced to small particles; blanched or pre-cooked; and/or frozen, canned or dried. Non-flavored dairy products including cheeses and plain yogurt, and simple prepared foods such as pastas or whole grain bread can also be considered to be minimally processed. If the package has a very short list of ingredients (1-4), the food is probably minimally processed, but check for added sugars.
• Unprocessed foods are those that are recognizable parts of fresh plants (leaves, stems, roots, fruits, seeds) or animals (cuts of meat, poultry or seafood, eggs).
Recommendations from the CDC Study
Dr. Zefeng Zhang, a CDC epidemiologist, says, “Healthy diets play an important role in maintaining a healthy heart and blood vessels. Eating ultra-processed foods often displaces healthier foods that are rich in nutrients, like fruit, vegetables, whole grains and lean protein, which are strongly linked to good heart health. In addition, ultra-processed foods are often high in salt, added sugars, saturated fat and other substances associated with increasing the risk of heart disease.”
To help prevent diseases, maintain a healthful weight and prolong your life, I recommend a plant-based, Mediterranean-style diet that includes plenty of vegetables, fruits, un-ground grains, beans, nuts and other seeds. People who are overweight or diabetic should restrict foods made from any type of ground-up grains (flour).