Did you know 100 calories of broccoli has more protein, vitamins, minerals, and less fat than 100 calories of steak? But which protein source is better – animal or plant? Does it matter? Does animal protein increase the risk of cardiovascular disease? Is plant protein a poor source? There is conflicting research and information on this topic, but like how your body uses protein, we break down all the nutritious facts here!
What is protein?1,2
Protein is a macronutrient that is involved in many of your body’s functional processes such as muscle and tissue repair, enzymatic reactions, hormone production, and transport of molecules like oxygen. Over 20% of your body is made of protein. Protein is made up of amino acids, but they are not stored in the body. Instead, amino acids are either made by your body or obtained from your food. The following nine amino acids are only obtained from your food: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
Protein is a component of the three macronutrients, along with carbohydrates and fat, that are essential in a healthy diet. Although the optimal diet type differs for everyone, diets should include a variety of whole foods like vegetables, fruits, whole grains, dairy, beans, seafood, lean meat, and nuts/seeds with minimally-processed foods like hot dogs, bacon, and ice cream. This method is called the Healthy Eating Plate.
How much protein do I need?2
Without enough protein, your body becomes weaker and you lose muscle mass. This makes it harder to carry out normal functions like growth and breathing. Too much protein becomes stored as fat which can make you gain weight. According to the National Academy of Medicine, for every 20 lbs of body weight, you need 7 grams of protein. If you are more physically active, you may require higher amounts of protein. Protein is found in a variety of foods, but not all sources are equal.
How are animal and plant protein sources different?1,3,4
Animal protein sources are known as complete while plant sources are incomplete. This means that animal sources have the nine essential amino acids we mentioned earlier, unlike the plant sources. The chart below displays examples of each type, along with some of their key points to remember when selecting a protein. Most sources of protein are from animals, but be careful because some animal sources may be packaged with higher amounts of saturated fat, cholesterol, calories, and poor fiber. Plant sources have many other nutrients like plenty of fiber, antioxidants, vitamins, and minerals!
Risk vs. Benefit1-3,5
You may have heard that plant protein sources are higher in nutrients and can lower your risk of diseases while animal protein sources may increase your risk of diseases. Yet, this is not exactly true. Plant sources include more fiber, minerals, antioxidants, and vitamins. Animal sources can include more zinc, vitamin D, vitamin B12, heme-iron, and docosahexaenoic acid (DHA) which is important for brain health. They also add some protection against diseases, but it is all about the specific food. Foods contain other components like fat, calories, and cholesterol. Like getting the right amount of protein, it is important you are getting it from a nutritious source.
When considering the risk of certain diseases like diabetes and cancer, the section below indicates how your risk is affected by your selected protein sources.
- Diabetes – Research has shown that a diet higher in red-meat increases your risk of type 2 diabetes while your risk can be lowered by eating more nuts and legumes. One study found that those who ate more red-meat had a higher risk of type 2 diabetes than those that rarely ate red or processed meat. The risk increased about 20% for each additional daily serving of red or processed meat. However, the risk lowered by 10% if a serving of nuts, whole grains, or low-fat dairy was consumed instead. Those that consume more plant protein sources tend to be less overweight which is another risk factor for type 2 diabetes.
- Cardiovascular disease – In the 20 year-long Nurses’ Health Study and Health Professionals Follow-Up Study, the risk of dying from cardiovascular disease such as heart disease, stroke, or heart attack increased by 13% for each additional daily 3 oz serving of red-meat the participants consumed. With each additional 1.5 oz serving of processed meat, the risk increased to 20%. However, this study did find that eating poultry, fish, and low-fat dairy was associated with a lower risk of cardiovascular disease. These results were mirrored by a meta-analysis with data from over 38 trials and 1,803 participants. Higher blood pressure, and levels of cholesterol, low density lipoprotein (LDL) or ‘bad’ cholesterol, and triglycerides were higher in those that consumed larger diets of red-meat than chicken, fish, or plant proteins.
- Cancer – Plant protein sources like vegetables and seeds contain phytochemicals which are chemicals that may protect you against cancer. A study conducted by the World Health Organization’s (WHO) International Agency for Research on Cancer (IARC) stated that processed meat is ‘carcinogenic to humans’ based on data from over 800 studies. These studies mainly showed an increased risk of colorectal cancer, but there were also associations with prostate, pancreatic, and stomach cancers. Even how the meat is cooked can affect the risk of cancer since grilling at high temperatures can release cancer-causing compounds.
- Premature death – From the Nurses’ Health Study and Health Professionals Follow-Up Study, the researchers found that a greater intake of red or processed meat like deli meats, sausage, and bacon was associated with a higher risk of death than plant protein sources. Eating processed or red-meat increased the risk of death by 13% to 20% in a study with data from over 21 countries.
- Weight control – After performing a 20 year-long study with 120,000 participants, the Harvard Chan School of Public Health found that those who ate more nuts lost about half a pound more weight every four years than those who ate more red and processed meats. Those that ate more red and processed meats gained an extra pound every four years. This study also found that eating more yogurt, chicken without skin, low-fat cheese, and peanut butter was associated with less weight gain than chicken with skin, regular cheese, and red-meat. Another study reported that by eating a daily serving of legumes, peas, or beans, this can increase fullness which may help with weight loss. Even eating eggs for breakfast has been shown to make you feel fuller.
What about vegans and vegetarians?1,3
If you are vegan or vegetarian, it’s possible to have a nutritious diet with all of your protein from plants. However, be sure you are consuming enough protein by calculating your protein intake with the formula discussed earlier. It is unclear if a higher protein intake is needed due to the lower digestibility of plant proteins, but it can be improved by boiling, fementing, or soaking them. Research also shows that combining incomplete protein sources to equal a complete protein is not necessary. As long as you consume enough variety of plant protein throughout the day, you do not need to combine incomplete sources at your meal.
Plant sources of protein can be poor in zinc, vitamin D, vitamin B12, heme-iron, DHA, and calcium. Try to eat dairy, leafy greens and drink plant milk to increase your vitamin D and calcium intake. To increase your zinc, eat more whole grains and beans in your diet. Lentils, spinach, and tofu are great sources of heme-iron. To increase your DHA, this can be done through eating algae or dietary supplements.
Do animal proteins really affect the environment?1
Greenhouse gases are those that are able to trap heat and radiation from Earth’s surface, creating a ‘greenhouse effect.’ About 17% of those gases come from nitrous oxide of fertilizers and irrigations, cutting down large areas of trees to make room for livestock, and methane from the manure of cattle, sheep, goats, and deer. As these effects increase, this contributes to climate change and destruction of ecosystems. It may seem like there is not much you can do to help this issue, but just by opting to eat less animal protein or eat more fish and chicken can make a difference!
Incorporating a variety of animal and plant protein sources are key for a nutritious diet. If you are vegan or vegetarian, be sure you eat a variety of plant protein sources to maximize your health. If you consume mostly animal, red-meat, or processed protein sources, try replacing some of those foods with plant proteins like beans, spinach, or nuts to lower your chance of diseases. You could even simply start with ‘Meatless Mondays!’ Before you make big changes to your diet or your protein intake, contact your health care provider or pharmacist today to ensure you are meeting your dietary needs.
- Best protein sources: Comparing animal and plant-based protein. Fullscript website. https://fullscript.com/blog/best-protein-sources. Accessed September 1, 2021.
- Protein. Harvard University website. https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/protein/. Accessed September 1, 2021.
- Animal vs plant protein – What’s the difference? Healthline website. https://www.healthline.com/nutrition/animal-vs-plant-protein. Accessed September 1, 2021.
- Nutrition – Plant vs animal protein. Dr. Hillel Harris website. https://drhillelharris.com/nutrition-plant-vs-animal-protein/. Accessed September 1, 2021.
- The difference between animal protein and plant protein. WebMD website. https://www.webmd.com/diet/difference-between-animal-protein-plant-protein#1. Accessed September 1, 2021.