We are all taught that protein is a super nutrient that will make us lean, strong, and healthy. We do need protein, but more is not necessarily better, and high-protein foods are not always healthful.
Why do we need protein?
In every cell in the human body, the DNA contains a code that tells the cell which proteins to make. Proteins have a lot of different roles in the body, some provide structure like collagen, some facilitate contact or movement, and others act as enzymes, signals, receptors, or transporters. In order to make all of these proteins, we have to consume protein and break it down into its constituent amino acids.
High-protein diets
High-protein foods do tend to be low in glycemic load. This is what the high-protein, low-carb diets get right. They avoid dangerous high-glycemic refined carbohydrates—sugar, white rice, and white flour products. In the process, they also limit nutrient-depleted, high-omega-6 and high-saturated fat oils. It is important to remember though, just like excess carbohydrate and fat calories, if you take in more protein calories than your body can use right away, those calories get stored as fat.
Refined carbohydrates are empty calories that are absorbed quickly, and they lead to overeating. Foods that are higher in protein, fiber, and/or resistant starch provide the satiety factor that is missing in refined carbohydrates and help to prevent blood glucose spikes, so we are not driven to overeat. For some people, high protein diets can be successful for weight loss in the short-term, but because they are typically so focused on animal foods, they are dangerous in the long-term. Low-carbohydrate/high-protein diets have been linked to increased risk of heart disease, cancer and premature death.1-3
Although plant protein is often described as “incomplete,” it has been known for many years that all plant foods contain all of the amino acids. Different plant foods may be low in a certain essential amino acid, but as long you are eating a variety of high-plant protein foods, you will get adequate amounts—but not too much—of all the essential amino acids.4 A low-quality plant-based diet, with a lot of rice, pasta, and white flour products will be lower than optimal in protein, and too high in glycemic load. Even a whole-food, plant-based diet could be too low in protein if it is heavily focused on grains, potatoes, and fruit, and low in beans (including soybeans), nuts, seeds, and greens. A plant protein powder supplement (non-soy, non-rice) in addition to a healthful diet is also appropriate, especially for those with higher protein needs, such as athletes and older adults. See the table below for the protein content of some typical foods in a Nutritarian diet.5
Older adults also require more protein than young and middle-aged adults. As we age, the body produces less growth hormone, leading to lower IGF-1 levels. Although excessively high IGF-1 levels are associated with an increase in cancer risk,6,7 excessively low IGF-1 is also a problem, because it is associated with reduced muscle mass, bone mass, and cognitive function in older adults.8-11
Animal protein and plant protein both provide us with adequate amounts of all of the amino acids, but animal protein is more concentrated in complete protein of a high biological value, so the body does not have to wait to utilize it to be combined with amino acids from other foods. Their proteins get absorbed and utilzed quickly, especially the amino acids that raise growth promoting hormones. For these reasons animal protein increases the body’s production of a hormone called IGF-1, which is associated with aging and an increased risk of several different cancers.12-13 One interesting study followed over 85,000 women and 44,000 men for more than 20 years, (26 years in women and 20 years in men) recording over 12,500 deaths. This research team found animal protein-rich diets were associated with a 43% increased risk of death from cardiovascular disease and cancer, compared to diets low in animal protein.14 In addition to animal protein, a diet high in animal products delivers additional harmful, pro-inflammatory, or pro-oxidant substances. Animal foods are higher in arachidonic acid, saturated fat, carnitine, heme iron, substances linked to inflammation, premature aging and other diseases.15-23
The U.S. Recommended Daily Allowance (RDA) for total protein is 0.8 g/kg/day (about 36 grams of protein per 100 pounds of body weight), based on early studies.24 However, more recent research using a newer method for determining protein needs suggests a minimum of 0.9 mg/kg/day for healthy young adults, and serious athletes and older adults require more. See the table below for estimated protein requirements in different life stages.25-27
It is not necessary to count the number of grams of protein in the food you eat every day to make sure you reach these numbers. If you are eating adequate calories and a variety of high-protein plant foods, it is unlikely you will consume too little protein. For a typical day, a Nutritarian menu of 1700-1800 calories provides approximately 60-70 grams of protein. The point is that when you eat an anti-cancer diet to promote longevity, you strive to consume more colorful plants, reducing animal protein considerably. It is both these features that lead to the dramatic disease-protective lifespan benefits.
Life stage
Estimated minimum protein requirement (g/ kg body mass/day)
g/day per 100 lb. body weight
Child
1.3
59
Healthy young adult
0.9
40.5
Pregnancy
1.2-1.5
54-68
Athlete
1.2-2.1
54-95
Older adult
0.85-1.5
39-68
References
Lagiou P, Sandin S, Lof M, et al. Low carbohydrate-high protein diet and incidence of cardiovascular diseases in Swedish women: prospective cohort study. BMJ 2012, 344:e4026.
Lagiou P, Sandin S, Weiderpass E, et al. Low carbohydrate-high protein diet and mortality in a cohort of Swedish women. J Intern Med 2007, 261:366-374.
Levine ME, Suarez JA, Brandhorst S, et al. Low Protein Intake Is Associated with a Major Reduction in IGF-1, Cancer, and Overall Mortality in the 65 and Younger but Not Older Population. Cell Metab 2014, 19:407-417.
Young VR, Pellett PL. Plant proteins in relation to human protein and amino acid nutrition. Am J Clin Nutr 1994, 59:1203S-1212S.
U.S. Department of Agriculture. Food Data Central [https://fdc.nal.usda.gov/]
Key TJ, Appleby PN, Reeves GK, Roddam AW. Insulin-like growth factor 1 (IGF1), IGF binding protein 3 (IGFBP3), and breast cancer risk: pooled individual data analysis of 17 prospective studies. The lancet oncology 2010, 11:530-542.
Rowlands MA, Gunnell D, Harris R, et al. Circulating insulin-like growth factor peptides and prostate cancer risk: a systematic review and meta-analysis. Int J Cancer 2009, 124:2416-2429.
Burgers AM, Biermasz NR, Schoones JW, et al. Meta-analysis and dose-response metaregression: circulating insulin-like growth factor I (IGF-I) and mortality. J Clin Endocrinol Metab 2011, 96:2912-2920.
Lamberts SW, van den Beld AW, van der Lely AJ. The endocrinology of aging. Science 1997, 278:419-424.
Doi T, Shimada H, Makizako H, et al. Association of insulin-like growth factor-1 with mild cognitive impairment and slow gait speed. Neurobiol Aging 2015, 36:942-947.
Calvo D, Gunstad J, Miller LA, et al. Higher serum insulin-like growth factor-1 is associated with better cognitive performance in persons with mild cognitive impairment. Psychogeriatrics 2013, 13:170-174.
Kaaks R. Nutrition, insulin, IGF-1 metabolism and cancer risk: a summary of epidemiological evidence. Novartis Found Symp 2004, 262:247-260; discussion 260-268.
Salvioli S, Capri M, Bucci L, et al. Why do centenarians escape or postpone cancer? The role of IGF-1, inflammation and p53. Cancer Immunol Immunother 2009, 58:1909-1917.
Fung TT, van Dam RM, Hankinson SE, et al. Low-carbohydrate diets and all-cause and cause-specific mortality: two cohort studies. Ann Intern Med 2010, 153:289-298.
Vergnaud AC, Norat T, Romaguera D, et al. Meat consumption and prospective weight change in participants of the EPIC-PANACEA study. Am J Clin Nutr 2010, 92:398-407.
Brewer GJ. Iron and copper toxicity in diseases of aging, particularly atherosclerosis and Alzheimer's disease. Experimental Biology and Medicine 2007, 232:323-335.
Brewer GJ. Risks of copper and iron toxicity during aging in humans. Chemical research in toxicology 2010, 23:319-326.
Padler-Karavani V, Yu H, Cao H, et al. Diversity in specificity, abundance, and composition of anti-Neu5Gc antibodies in normal humans: potential implications for disease. Glycobiology 2008, 18:818-830.
Koeth RA, Wang Z, Levison BS, et al. Intestinal microbiota metabolism of l-carnitine, a nutrient in red meat, promotes atherosclerosis. Nat Med 2013.
Tang WH, Wang Z, Levison BS, et al. Intestinal microbial metabolism of phosphatidylcholine and cardiovascular risk. N Engl J Med 2013, 368:1575-1584.
de Lorgeril M, Salen P. New insights into the health effects of dietary saturated and omega-6 and omega-3 polyunsaturated fatty acids. BMC Med 2012, 10:50.
Lunn JC, Kuhnle G, Mai V, et al. The effect of haem in red and processed meat on the endogenous formation of N-nitroso compounds in the upper gastrointestinal tract. Carcinogenesis 2007, 28:685-690.
Zheng W, Lee SA. Well-done meat intake, heterocyclic amine exposure, and cancer risk. Nutr Cancer 2009, 61:437-446.
Rand WM, Pellett PL, Young VR. Meta-analysis of nitrogen balance studies for estimating protein requirements in healthy adults. Am J Clin Nutr 2003, 77:109-127.
Matsumoto M, Narumi-Hyakutake A, Kakutani Y, et al. Evaluation of protein requirements using the indicator amino acid oxidation method: a scoping review. The Journal of Nutrition 2023, 153:3472-3489.
Witard OC, McGlory C, Hamilton DL, Phillips SM. Growing older with health and vitality: a nexus of physical activity, exercise and nutrition. Biogerontology 2016, 17:529-546.
Traylor DA, Gorissen SHM, Phillips SM. Perspective: Protein Requirements and Optimal Intakes in Aging: Are We Ready to Recommend More Than the Recommended Daily Allowance? Adv Nutr 2018, 9:171-182.
Joel Fuhrman, M.D. is a board-certified family physician, seven-time New York Times bestselling author and internationally recognized expert on nutrition and natural healing, who specializes in preventing and reversing disease through nutritional methods. Dr. Fuhrman coined the term “Nutritarian” to describe his longevity-promoting, nutrient dense, plant-rich eating style.
For over 30 years, Dr. Fuhrman has shown that it is possible to achieve sustainable weight loss and reverse heart disease, diabetes and many other illnesses using smart nutrition. In his medical practice, and through his books and PBS television specials, he continues to bring this life-saving message to hundreds of thousands of people around the world.
How Plant Protein Wins Over Animal Protein
April 23, 2024 by Joel Fuhrman, MD
We are all taught that protein is a super nutrient that will make us lean, strong, and healthy. We do need protein, but more is not necessarily better, and high-protein foods are not always healthful.
Why do we need protein?
In every cell in the human body, the DNA contains a code that tells the cell which proteins to make. Proteins have a lot of different roles in the body, some provide structure like collagen, some facilitate contact or movement, and others act as enzymes, signals, receptors, or transporters. In order to make all of these proteins, we have to consume protein and break it down into its constituent amino acids.
High-protein diets
High-protein foods do tend to be low in glycemic load. This is what the high-protein, low-carb diets get right. They avoid dangerous high-glycemic refined carbohydrates—sugar, white rice, and white flour products. In the process, they also limit nutrient-depleted, high-omega-6 and high-saturated fat oils. It is important to remember though, just like excess carbohydrate and fat calories, if you take in more protein calories than your body can use right away, those calories get stored as fat.
Refined carbohydrates are empty calories that are absorbed quickly, and they lead to overeating. Foods that are higher in protein, fiber, and/or resistant starch provide the satiety factor that is missing in refined carbohydrates and help to prevent blood glucose spikes, so we are not driven to overeat. For some people, high protein diets can be successful for weight loss in the short-term, but because they are typically so focused on animal foods, they are dangerous in the long-term. Low-carbohydrate/high-protein diets have been linked to increased risk of heart disease, cancer and premature death.1-3
Related: Eat Plant Protein to Live Longer
Plant protein vs. animal protein
Although plant protein is often described as “incomplete,” it has been known for many years that all plant foods contain all of the amino acids. Different plant foods may be low in a certain essential amino acid, but as long you are eating a variety of high-plant protein foods, you will get adequate amounts—but not too much—of all the essential amino acids.4 A low-quality plant-based diet, with a lot of rice, pasta, and white flour products will be lower than optimal in protein, and too high in glycemic load. Even a whole-food, plant-based diet could be too low in protein if it is heavily focused on grains, potatoes, and fruit, and low in beans (including soybeans), nuts, seeds, and greens. A plant protein powder supplement (non-soy, non-rice) in addition to a healthful diet is also appropriate, especially for those with higher protein needs, such as athletes and older adults. See the table below for the protein content of some typical foods in a Nutritarian diet.5
Related: Why vegetarians and vegans could have a higher risk of bone fractures
Food
Serving
Protein (g)
Kale
1 cup (cooked)
4.0
Broccoli
1 cup (cooked)
4.5
Almonds
1 ounce
6.0
Quinoa
1 cup (cooked)
7.5
Green peas
1 cup (cooked)
8.2
Pumpkin seeds
1 ounce
8.6
Hemp seeds
1 ounce
8.8
Black beans
1 cup (cooked)
15.9
Edamame
1 cup (cooked)
18.5
Tofu (extra firm)
½ 14-ounce block
20.25
Tempeh
1 cup
33.7
Older adults also require more protein than young and middle-aged adults. As we age, the body produces less growth hormone, leading to lower IGF-1 levels. Although excessively high IGF-1 levels are associated with an increase in cancer risk,6,7 excessively low IGF-1 is also a problem, because it is associated with reduced muscle mass, bone mass, and cognitive function in older adults.8-11
Related: Optimal IGF-1 Levels for Longevity
Animal protein and plant protein both provide us with adequate amounts of all of the amino acids, but animal protein is more concentrated in complete protein of a high biological value, so the body does not have to wait to utilize it to be combined with amino acids from other foods. Their proteins get absorbed and utilzed quickly, especially the amino acids that raise growth promoting hormones. For these reasons animal protein increases the body’s production of a hormone called IGF-1, which is associated with aging and an increased risk of several different cancers.12-13 One interesting study followed over 85,000 women and 44,000 men for more than 20 years, (26 years in women and 20 years in men) recording over 12,500 deaths. This research team found animal protein-rich diets were associated with a 43% increased risk of death from cardiovascular disease and cancer, compared to diets low in animal protein.14 In addition to animal protein, a diet high in animal products delivers additional harmful, pro-inflammatory, or pro-oxidant substances. Animal foods are higher in arachidonic acid, saturated fat, carnitine, heme iron, substances linked to inflammation, premature aging and other diseases.15-23
Related: Animal products, the microbiome, and heart disease
How much protein?
The U.S. Recommended Daily Allowance (RDA) for total protein is 0.8 g/kg/day (about 36 grams of protein per 100 pounds of body weight), based on early studies.24 However, more recent research using a newer method for determining protein needs suggests a minimum of 0.9 mg/kg/day for healthy young adults, and serious athletes and older adults require more. See the table below for estimated protein requirements in different life stages.25-27
It is not necessary to count the number of grams of protein in the food you eat every day to make sure you reach these numbers. If you are eating adequate calories and a variety of high-protein plant foods, it is unlikely you will consume too little protein. For a typical day, a Nutritarian menu of 1700-1800 calories provides approximately 60-70 grams of protein. The point is that when you eat an anti-cancer diet to promote longevity, you strive to consume more colorful plants, reducing animal protein considerably. It is both these features that lead to the dramatic disease-protective lifespan benefits.
Life stage
Estimated minimum protein requirement (g/ kg body mass/day)
g/day per 100 lb. body weight
Child
1.3
59
Healthy young adult
0.9
40.5
Pregnancy
1.2-1.5
54-68
Athlete
1.2-2.1
54-95
Older adult
0.85-1.5
39-68
Joel Fuhrman, M.D. is a board-certified family physician, seven-time New York Times bestselling author and internationally recognized expert on nutrition and natural healing, who specializes in preventing and reversing disease through nutritional methods. Dr. Fuhrman coined the term “Nutritarian” to describe his longevity-promoting, nutrient dense, plant-rich eating style.
For over 30 years, Dr. Fuhrman has shown that it is possible to achieve sustainable weight loss and reverse heart disease, diabetes and many other illnesses using smart nutrition. In his medical practice, and through his books and PBS television specials, he continues to bring this life-saving message to hundreds of thousands of people around the world.