How many processed meats, sugary drinks, and foods containing trans fatty acids are safe to eat? According to a new analysis, not very much.
The paper, published in Nature Medicine, found that consuming even less than a strip of bacon or a can of soda per day was linked to a higher risk of type 2 diabetes, colon cancer, or ischemic heart disease.
Several studies suggest that processed meats, sugar-sweetened beverages, and trans fats contribute to chronic disease, but few have investigated how much of these substances is safe to consume.
The researchers determined that minimizing your intake of each of these food groups can significantly reduce your risk of life-threatening illness.
“It is important to not eat these types of foods regularly, and certainly not daily,” McKale Montgomery, PhD, RD, LD, a registered dietitian and assistant professor of nutritional sciences at Texas Christian University, told Health.
To assess how much these items contribute to disease risk, researchers evaluated over 60 studies that previously investigated the relationship between the three food categories and a person’s risk of type 2 diabetes, colorectal cancer, and ischemic heart disease. A higher intake of each group was consistently linked to a significantly increased risk of chronic disease.
More specifically, consuming very little amounts of processed foods and drinks upped the risk, and the more you eat, the greater your risk.
- When it came to processed meat, consuming as little as .6 grams to 57 grams (about five slices of bacon) a day was associated with an 11% and 7% greater risk of type 2 diabetes and colorectal cancer, respectively. Eating 50 grams a day (roughly one hot dog) was linked to a 30% higher risk of type 2 diabetes and 26% increased chances of colon cancer.
- Consuming between 1.5 grams and 390 grams of sugar-sweetened drinks a day (about a 12-ounce soda) was linked to an 8% higher risk of type 2 diabetes and a slightly heightened risk of ischemic heart disease.
- Meanwhile, trans fats comprising 0.25 to 2.56% of daily calories was associated with a 3% greater risk of ischemic heart disease.
It’s still unclear why processed foods seem to contribute to chronic diseases, but scientists have a handful of theories, Montgomery said. For example, these items have been linked to increased inflammation and oxidative stress, both of which are known to contribute to diabetes and heart disease.
But there are likely multiple other factors at play, too:
Processed Meats
Meats like hot dogs, sausages, and cold cuts are high in fat, saturated fat, and sodium. Eating too much can affect your lipid levels, raise cholesterol, and increase blood pressure, respectively, Montgomery said. The techniques used to make processed meats—think: smoking, curing, and cooking at high temperatures—can also lead to the formation of harmful compounds that are carcinogenic and damage DNA.
Not to mention, processed meats are also packed with nitrates and nitrites—additives linked to colorectal and other cancers. Meanwhile, heme iron, which is found in red meat, can potentially lead to colon cancer by damaging the lining of the colon, some research suggests.
Sugary Drinks
Consuming sugary beverages regularly can contribute to obesity or excess weight, which are leading factors for heart disease. “The calories folks consume from liquids do not contribute to a sense of satiety,” said Rebecca Blake, RD, MS, CDN, a registered dietitian based in New York City. By drinking sodas and fruit juices, we tend to consume more calories than we need to feel full, added Blake.
Furthermore, research shows that added sugars may disrupt the gut microbiome and decrease the diversity of gut bacteria. This can impair the body’s ability to absorb nutrients, trigger inflammation, and lead to metabolic dysregulation, Ashley Koff, RD, the nutrition director for UC-Irvine’s Susan Samueli Integrative and Functional Medicine Fellowship, told Health.
Trans Fatty Acids
Too many trans fats—inserted into packaged goods like cakes, cookies, frozen pizza, and crackers to enhance taste and texture—can boost LDL levels (the “bad” cholesterol) and decrease HDL levels ( the “good” cholesterol). “Each of these by themselves are strongly associated with heart disease, but of course both increase heart disease risk even further,” Montgomery said.
Scientists are only just beginning to understand how many processed foods may be safe to consume regularly. In general, however, it’s best to limit your consumption of them. “Too much of any one thing is generally a bad thing,” Montgomery said.
In fact, the World Health Organization recommends that “people who eat meat should moderate the consumption of processed meat to reduce the risk of colorectal cancer.” According to Blake, a realistic approach if you really want to eat them is to limit consumption to only once or twice a month. The same goes for sugar-sweetened beverages. “Once in a while is okay,” she told Health.
“If you are consuming enough fiber and protein, eating within your calorie needs, and limiting your fat and sugar intake most days, then an occasional hotdog or sugar sweetened beverage is okay,” Montgomery agreed.
As for trans fats, they’ve been banned in the U.S. since 2018, making them easier to avoid—though trace amounts can still be found in some processed foods.
In general, you can mitigate the risks of occasional snacking on processed foods by eating a healthy diet. Prioritize fruits, vegetables, whole grains, poultry, fish, and nuts over processed meats and snacks, the AHA advises.
Instead of sodas or sweetened coffee drinks, opt for water with a lemon or a seltzer. “The desire for the sugar tends to decrease with less consumption,” Blake said.
