As more people learn about the health benefits of eating plant-based foods, “Meatless Mondays” have grown in popularity. Now, nutrition experts and doctors promote expanding this dietary recommendation to at least two days a week. Researchers have found that men and women who eat red meats only five times a week are statistically less likely to get certain cancers.
Does red meat cause cancer?
Eating meat raises the risk of certain cancers because of the increased consumption of carcinogens (cancer-causing agents). “By reducing the amount of meat consumed, one naturally reduces the number of potential carcinogens in the diet, which may reduce the risk of cancer,” says Anna Gonzalez, RDN, LDN, oncology dietitian with Sylvester Comprehensive Cancer Center.
What are carcinogens?
Carcinogens are substances capable of causing cancer in living tissue. The International Agency for Research on Cancer uses a classification system to rank the risk to humans from carcinogenic compounds.
Red meats are classified as a group 2A carcinogen (probably carcinogenic to humans) based on limited evidence showing links to cancer. Along with tobacco and alcohol, processed meats are classified as a group 1 carcinogen (carcinogenic to humans) based on sufficient evidence.
Nitrates are compounds that plants naturally obtain from the soil.
Higher concentrations can be found in crops grown with conventional fertilizers. Both plant nitrates and synthetic nitrates are added in high concentrations to meats to help prevent the growth of bacteria.
Synthetic nitrates pose a risk to humans that naturally occurring nitrates may not. Although naturally occurring nitrates have been linked to health benefits such as cardiovascular health, when synthetic nitrates are broken down in the digestive system, they produce toxic compounds (nitrosamines) that may affect the gut lining.
Heme iron is the iron-rich red pigment in meat that produces carcinogenic nitrosamines (N-nitroso).
“Although heme iron is found naturally in human blood when digested in the gut, the resulting chemical can lead to damage in the cells lining the gut,” says Gonzalez. “This repeated damage can cause abnormal cell division, also known as cancer.”
Heterocyclic amines (HCA) and polycyclic amines (PCA) are produced when meat is exposed to high temperatures during frying, grilling/barbecuing, and smoking.
These carcinogenic chemicals can damage gut cells.
“Cooked meat should reach an internal temperature of 145 °F, meaning elevated temperatures are used,” Gonzalez says.
“Using extra virgin olive oil to cook ingredients that require elevated temperatures will cause the oil to burn because olive oil has a low smoke point. The burning of oils leads to the production of polycyclic aromatic hydrocarbons (PAH), also found to have cancer-causing effects. A better alternative when cooking in high temperatures is avocado oil or if olive oil is preferred, opt for a refined or light olive oil.”
How much meat should you eat?
Recommendations from the World Cancer Research Fund (WCRF) include limiting red meat to only moderate amounts per week. This means no more than three weekly portions of 350 to 500 grams (12 to 18 ounces) of cooked red meat (beef, pork, and lamb).
The WCRF recommends consuming little to no processed meats (such as pepperoni, salami, bacon, sausage, and sliced deli meats) because a safe, minimal intake level has not been found.
“Even chicken and turkey deli slices that are labeled free of nitrates, added hormones, and antibiotics may not be considered a safer alternative,” Gonzalez says.
“USDA regulations permit deli meats to contain nitrates that have been extracted from conventionally grown plants like celery and claim the product is nitrate-free,” she says. “These concentrated curing agents react with the gut’s highly acidic environment creating nitrosamines, which have been linked to cancer by damaging the gut lining.”
What should you eat instead?
“By choosing nutritious sources of protein that are lower in saturated fat and rich in fiber and protein, we may lower one’s risk of developing certain cancers,” says Federika Garcia, M.S., RDN, LDN, CNSC, a senior clinical dietitian with Sylvester.
“It is recommended that in lieu of simply eliminating meat, supplement your diet with an increased intake of plant-based, protein-rich foods,” Gonzalez says. “This increases the number of cancer-fighting agents in the diet. Plants contain phytochemicals (plant chemicals) whose benefits include antioxidant and anti-inflammatory properties.”
“The increased fiber intake also plays a role in preventing cancer. Some studies have found that 10 grams of daily fiber intake decreased the risk of colorectal cancer by 10%.” Meat provides zero dietary fiber.
Enjoy these plant-based alternatives.
Whole foods high in protein and fiber:
- Legumes (beans, lentils, chickpeas, green peas, soybeans, peanuts)
- Seeds (flax, chia, hemp)
Fiber-rich, low-fat whole grains:
- Brown rice
- Whole wheat
- Sprouted grain bread
- Spelt (hulled wheat)
Vegetables with protein:
- Sweet corn
- Brussels Sprouts
- Nut butter (without added oils and sugars)
- Dairy-free milk without added sugars and gums (flax, soy, oat, almond, coconut)
- Some meat-alternative products (such as patties made from beets, brown rice, beans, mushrooms, and green vegetables)
What about other animal proteins?
“People who consume seafood, eggs, and lean poultry can also combine their meals with high-fiber plant-based foods to obtain greater health benefits,” Garica says. “There can be a sweet spot where animal foods can be combined with plant-based foods for those more hesitant to transition to a vegetarian diet.”
Animal products that are low in carcinogens:
- Fish (not fried)
- Lean chicken and turkey without the skin (not processed deli slices)
- Greek yogurt (without added sugars)
- Kefir (probiotic-rich yogurt drink)
- Egg whites
- Reduced-fat cheeses (cottage cheese, mozzarella, feta)
“A healthier alternative to a sandwich with deli meat is a tuna salad sandwich on whole-wheat bread made with Greek yogurt instead of mayo, mustard, lemon, and a mix of vegetables or an egg salad sandwich,” Garcia says. “Lean poultry with lentils, hard-boiled eggs in a salad with chickpeas, and omega 3-rich salmon with white beans and mixed vegetables can all make healthy, nutritious red meat alternatives.
"For vegetarians and vegans, mashed chickpeas or white beans with avocado and hemp seeds can serve as a healthy, plant-based, fiber-and-protein-rich alternative.”
Dana Kantrowitz is a contributing writer for UMiami Health News.
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