The foods most worth avoiding fall into a few clear categories: ultra-processed packaged foods, processed meats, items high in added sugar, and certain high-mercury fish. Some of these carry long-term risks for heart disease and cancer, while others pose more immediate food safety concerns. Here’s what the evidence says about each one and why it matters for your health.
Ultra-Processed Foods
Ultra-processed foods are products made mostly from industrial ingredients you wouldn’t find in a home kitchen: hydrogenated oils, high-fructose corn syrup, emulsifiers, artificial colors, and flavor enhancers. Think frozen dinners, packaged snack cakes, flavored chips, instant noodles, and most fast food. These aren’t just “junk food” in the vague sense. A meta-analysis of 22 large studies found that people who ate the most ultra-processed food had a 17% higher risk of cardiovascular disease, a 23% higher risk of coronary heart disease, and a 9% higher risk of stroke compared to those who ate the least.
The problem isn’t any single ingredient. It’s the combination of excess sodium, added sugars, unhealthy fats, and a near-total lack of fiber and micronutrients. These foods are also engineered to be easy to overeat, which compounds the damage over time. If your diet leans heavily on things that come in wrappers with long ingredient lists, replacing even a portion of those with whole foods makes a measurable difference.
Processed Meats
Hot dogs, bacon, sausage, deli turkey, salami, and other cured or smoked meats are in a category of their own. The World Health Organization’s cancer research agency classifies processed meat as a Group 1 carcinogen for colorectal cancer. That’s the same confidence level as tobacco, though the actual magnitude of risk is much smaller. The concern centers on chemicals that form during curing and smoking, which can damage the lining of the colon over time.
Processed meats also show up repeatedly in foodborne illness data. The CDC identifies meat and poultry as the most common sources of fatal food infections, driven largely by Salmonella and Listeria. Several large Listeria outbreaks have been traced specifically to sliced deli turkey. If you eat deli meats, heating them until steaming reduces that risk considerably.
Foods Still Hiding Trans Fats
Industrial trans fats are largely banned in the United States and many other countries, but they haven’t disappeared from the food supply. Regulatory loopholes allow small amounts to go unlabeled, and foods sold without nutrition labels (bakery items, restaurant meals, fried street food) can still contain significant levels. Pastries, cream-filled baked goods, biscuits, fast food like pizza, burgers, and fries, and packaged snack products have all been found to exceed safe trans fat limits in recent testing across multiple countries.
Trans fats raise your “bad” cholesterol while lowering your “good” cholesterol, a combination that’s uniquely damaging to blood vessels. The ingredient to watch for on labels is “partially hydrogenated oil.” If you see it listed, the product contains trans fat regardless of what the nutrition panel says. Products can legally round down to zero if they contain less than 0.5 grams per serving, so small servings can mask meaningful amounts.
High-Mercury Fish
Fish is generally healthy, but a handful of species accumulate dangerous levels of mercury, a heavy metal that damages the nervous system. This is especially important for pregnant women, nursing mothers, and young children, though everyone benefits from avoiding the highest-mercury options. The FDA places seven types of fish in its “Choices to Avoid” category for the highest mercury levels:
- King mackerel
- Marlin
- Orange roughy
- Shark
- Swordfish
- Tilefish (Gulf of Mexico)
- Bigeye tuna
These are all large, long-lived predatory fish that accumulate mercury from everything they eat over their lifespans. Canned light tuna, salmon, shrimp, and sardines are all lower-mercury choices that still give you the benefits of omega-3 fatty acids.
Foods Loaded With Added Sugar
The latest U.S. Dietary Guidelines take a harder stance on sugar than ever before, stating that “no amount of added sugars is recommended or considered part of a healthy or nutritious diet.” In practical terms, they recommend no single meal should contain more than 10 grams of added sugar. That’s a significant tightening from the previous guideline of no more than 50 grams per day on a 2,000-calorie diet.
To put that in perspective, a single can of regular soda contains about 39 grams. A flavored yogurt can have 15 to 20 grams. Bottled pasta sauce, granola bars, flavored oatmeal, and even whole wheat bread often contain more added sugar than you’d expect. The biggest sources for most people are sugary drinks (soda, sweet tea, fruit punch, energy drinks), desserts, and sweetened breakfast foods. Checking the “added sugars” line on nutrition labels is the fastest way to identify where the excess is coming from in your own diet.
Too Much Sodium
The average American eats over 3,300 milligrams of sodium per day. The American Heart Association recommends no more than 2,300 mg, with an ideal target of 1,500 mg for most adults. Simply cutting 1,000 mg from your daily intake can measurably improve blood pressure and heart health.
Most excess sodium doesn’t come from the salt shaker. It’s baked into restaurant food, canned soups, frozen meals, bread, cheese, deli meats, and condiments. A single fast food meal can easily deliver 1,500 to 2,000 mg. Reading labels helps, but the most effective strategy is cooking more meals from whole ingredients, where you control how much salt goes in.
Raw and Undercooked Poultry
Raw chicken is one of the most common vehicles for Salmonella and Campylobacter, two bacteria responsible for millions of foodborne illnesses each year. The CDC notes that poultry is a leading source of fatal food infections. A common mistake is washing raw chicken before cooking it, which doesn’t remove bacteria and actually splashes contaminated water onto nearby surfaces, utensils, and other foods. The only reliable way to kill these pathogens is cooking poultry to an internal temperature of 165°F (74°C), verified with a meat thermometer.
Charred and Deep-Fried Foods
How food is cooked matters almost as much as what the food is. High-temperature cooking methods like frying, grilling, and roasting produce compounds called advanced glycation end-products (AGEs) that promote inflammation and are linked to metabolic problems including insulin resistance. Fried chicken, bacon, and beef are among the highest AGE foods. Dry-heat snacks like chips, crackers, and cookies also rank high per gram.
Browning also produces acrylamide, a compound that forms when starchy foods hit temperatures above about 250°F (120°C). Fried potatoes, toasted bread, and breakfast cereals are the main dietary sources. The darker the browning, the higher the acrylamide content. This doesn’t mean you need to avoid all cooked food. Steaming, poaching, and stewing produce far fewer of these compounds than frying or grilling. Aiming for a golden color rather than a deep brown on starchy foods is a simple way to reduce your exposure.
What This Means in Practice
You don’t need to eliminate every item on this list to see health benefits. The biggest returns come from a few shifts: replacing ultra-processed staples with whole foods, swapping sugary drinks for water, choosing lower-mercury fish, and cooking at lower temperatures more often. Small, consistent changes to what you eat regularly matter far more than occasional indulgences. The foods that cause the most damage are the ones you eat every day without thinking about them.