Diets that replaced red meat with healthy plant proteins led to decreases in risk factors for cardiovascular disease (CVD), according to a new study from Harvard T.H. Chan School of Public Health and Purdue University.
The study is the first meta-analysis of randomized controlled trials examining the health effects of red meat by substituting it for other specific types of foods.
The study was published in the journal Circulation.
“Previous findings from randomized controlled trials evaluating the effects of red meat on cardiovascular disease risk factors have been inconsistent.
But our new study, which makes specific comparisons between diets high in red meat versus diets high in other types of foods, shows that substituting red meat with high-quality protein sources lead to more favorable changes in cardiovascular risk factors,” said Marta Guasch-Ferré, research scientist in the Department of Nutrition and lead author of the study.
The study included data from 36 randomized controlled trials involving 1,803 participants.
The researchers compared people who ate diets with red meat with people who ate more of other types of foods (i.e. chicken, fish, carbohydrates, or plant proteins such as legumes, soy, or nuts), looking at blood concentrations of cholesterol, triglycerides, lipoproteins, and blood pressure – all risk factors for CVD.
The study found that when diets with red meat were compared with all other types of diets combined, there were no significant differences in total cholesterol, lipoproteins, or blood pressure, although diets higher in red meat did lead to higher tryglyceride concentrations than the comparison diets.
However, researchers found that diets higher in high-quality plant protein sources such as legumes, soy, and nuts resulted in lower levels of both total and LDL (“bad”) cholesterol compared to diets with red meat.
The results are consistent with long-term epidemiologic studies showing lower risks of heart attacks when nuts and other plant sources of protein are compared to red meat, the authors said.
The findings also suggest that the inconsistencies found in prior studies regarding the effects of red meat on cardiovascular risk factors may be due, in part, to the composition of the comparison diet.
They recommended that future studies take specific comparisons into account.
“Asking ‘Is red meat good or bad?’ is useless,” said Meir Stampfer, professor of epidemiology and nutrition and senior author of the study.
“It has to be ‘Compared to what?’
If you replace burgers with cookies or fries, you don’t get healthier.
But if you replace red meat with healthy plant protein sources, like nuts and beans, you get a health benefit.”
The authors recommended adherence to healthy vegetarian and Mediterranean-style diets, both for their health benefits and to promote environmental sustainability.
Fifteen best plant-based proteins
The right plant-based foods can be excellent sources of protein and other nutrients, often with fewer calories than animal products.
Some plant products, such as soy beans and quinoa, are complete proteins, which means that they contain all nine essential amino acids that humans need. Others are missing some of these amino acids, so eating a varied diet is important.
The following healthful, plant-based foods have a high-protein content per serving:
1. Tofu, tempeh, and edamame
Soy products such as tofu, tempeh, and edamame are among the richest sources of protein in a vegan diet.
Soy products are among the richest sources of protein in a plant-based diet. The protein content varies with how the soy is prepared:
- firm tofu (soybean curds) contains about 10 g of protein per ½ cup
- edamame beans (immature soybeans) contain 8.5 g of protein per ½ cup
- tempeh contains about 15 g of protein per ½ cup
Tofu takes on the flavor of the dish it is prepared in so that it can be a versatile addition to a meal.
People can try tofu, as a meat substitute, in a favorite sandwich or soup. Tofu is also a popular meat substitute in some dishes, such as kung pao chicken and sweet and sour chicken.
These soy products also contain good levels of calcium and iron, which makes them healthful substitutes for dairy products.
Red or green lentils contain plenty of protein, fiber, and key nutrients, including iron and potassium.
Cooked lentils contain 8.84 g of protein per ½ cup.
Lentils are a great source of protein to add to a lunch or dinner routine. They can be added to stews, curries, salads, or rice to give an extra portion of protein.
Cooked chickpeas are high in protein, containing around 7.25 g per ½ cup.
Chickpeas can be eaten hot or cold, and are highly versatile with plenty of recipes available online. They can, for example, be added to stews and curries, or spiced with paprika and roasted in the oven.
A person can add hummus, which is made from chickpea paste, to a sandwich for a healthful, protein-rich alternative to butter.
Peanuts are protein-rich, full of healthful fats, and may improve heart health. They contain around 20.5 g of protein per ½ cup.
Peanut butter is also rich in protein, with 8 g per tablespoon, making peanut butter sandwiches a healthful complete protein snack.
Almonds offer 16.5 g of protein per ½ cup. They also provide a good amount of vitamin E, which is great for the skin and eyes.
Spirulina is blue or green algae that contain around 8 g of protein per 2 tablespoons. It is also rich in nutrients, such as iron, B vitamins — although not vitamin B-12 — and manganese.
Spirulina is available online, as a powder or a supplement. It can be added to water, smoothies, or fruit juice. A person can also sprinkle it over salad or snacks to increase their protein content.
Quinoa is a grain with a high-protein content, and is a complete protein. Cooked quinoa contains 8 g of protein per cup.
This grain is also rich in other nutrients, including magnesium, iron, fiber, and manganese. It is also highly versatile.
Quinoa can fill in for pasta in soups and stews. It can be sprinkled on a salad or eaten as the main course.
Mycoprotein is a fungus-based protein. Mycoprotein products contain around 13 g of protein per ½ cup serving.
Products with mycoprotein are often advertised as meat substitutes and are available in forms such as “chicken” nuggets or cutlets. However, many of these products contain egg white, so people must be sure to check the label.
A very small number of people are allergic to Fusarium venenatum, the fungus from which the mycoprotein brand known as Quorn is made. People with a history of mushroom allergies or with many food allergies may wish to consider another protein source.
9. Chia seeds
Chia and hemp seeds are complete sources of protein that can be used to make smoothies, yogurts, and puddings.
Seeds are low-calorie foods that are rich in fiber and heart-healthy Omega-3 fatty acids. Chia seeds are a complete source of protein that contain 2 g of protein per tablespoon.
Try adding chia seeds to a smoothie, sprinkling them on top of a plant-based yogurt, or soaking them in water or almond milk to make a pudding.
Chia seeds are available from some supermarkets, health food stores, or to buy online.
10. Hemp seeds
Similarly to chia seeds, hemp seeds are a complete protein. Hemp seeds offer 5 g of protein per tablespoon. They can be used in a similar way to chia seeds. Hemp seeds can also be bought online.
11. Beans with rice
Separately, rice and beans are incomplete protein sources. Eaten together, this classic meal can provide 7 g of protein per cup.
Try rice and beans as a side dish, or mix rice, beans, and hummus together then spread on Ezekiel bread, which is made from sprouted grains, for a savory, protein-packed meal.
A large baked potato offers 8 g of protein per serving. Potatoes are also high in other nutrients, such as potassium and vitamin C.
Add 2 tablespoons of hummus for a flavorful snack that is healthier than butter-covered potatoes and increases the protein content. Two tablespoons of hummus contain about 3 g of protein.
13. Protein-rich vegetables
Many dark-colored, leafy greens and vegetables contain protein. Eaten alone, these foods are not enough to meet daily protein requirements, but a few vegetable snacks can increase protein intake, particularly when combined with other protein-rich foods.
- a single, medium stalk of broccoli contains about 4 g of protein
- kale offers 2 g of protein per cup
- 5 medium mushrooms offer 3 g of protein
Try a salad made from baby greens with some quinoa sprinkled on top for a protein-rich meal.
Seitan is a complete protein made from mixing wheat gluten with various spices. The high-wheat content means that it should be avoided by people with celiac or gluten intolerance. For others, it can be a protein-rich healthful meat substitute.
When cooked in soy sauce, which is rich in the amino acid lysine, seitan becomes a complete protein source offering 21 g per 1/3 cup.
15. Ezekiel bread
Ezekiel bread is a nutrient-dense alternative to traditional bread. It is made from barley, wheat, lentils, millet, and spelt. Ezekiel bread is an excellent choice for bread lovers who want a more nutritious way to eat toast or sandwiches.
Ezekiel bread offers 4 g of protein per slice. Get even more protein by toasting Ezekiel bread and spreading it with peanut or almond butter.
More information: Marta Guasch-Ferré et al, Meta-Analysis of Randomized Controlled Trials of Red Meat Consumption in Comparison With Various Comparison Diets on Cardiovascular Risk Factors, Circulation (2019). DOI: 10.1161/CIRCULATIONAHA.118.035225
Provided by Harvard T.H. Chan School of Public Health