How many grams of protein can we use?

For the average 170-pound woman in the United States, this equals 123-169 grams of protein per day.

The easiest math?

Shoot for one gram of protein per pound per day, or about 40 grams of protein 4 times per day for the average-sized woman. And don’t stress it if you miss the mark. 

Thanks to research on sarcopenia (described here) and the importance of avoiding this unpopular but massively impactful diagnosis, it seems logical to maximize muscle building, especially before menopause. The hormonal changes that occur during perimenopause and menopause can, without our close attention, lead to loss of skeletal muscle mass and higher risks of sarcopenia and osteoporosis.

An observational study of 281 older women divided into those with low muscle mass and high muscle mass found a women’s protein requirement similar to that of Schoenfeld and Aragon (2).

The use of food questionnaires in the study also identified nutrients that may contribute to maintaining muscle mass, such as iodine, polyunsaturated fatty acids, vitamin E, and manganese.

The authors recommend that women’s protein requirements consist of a minimum of 1.17 g/kg/day for high relative skeletal muscle mass. To note, the study also gathered information about physical activity—those with higher muscle mass percentages were more active than those with lower scores.

According to these studies, we can use more protein than the RDA recommends, and we can use it to create bodies that are resilient and strong.

However, there are some nutrition minds who disagree with this assessment.

Sally Fallon, president of the WAPF, has said that athletic types (ahem, moms) need only about 20% of macronutrients as protein. For a standard 2000-calorie diet, this equals approximately 400 calories from protein or 100 grams of protein per day. And it doesn’t account for fluctuations in caloric intake. So, this recommendation may leave you low on the protein you need for basic physiological functions, not to mention the maintenance of muscle mass.

Is so much protein sustainable? Ethical?

The main question I’ve gotten regarding the higher-than-RDA recommendation for women’s protein requirements is: Is it sustainable? And is it ethical?

It’s a worthy query and one that I want to take the time to explore.

The world population is projected to be over 9 billion people by 2050, and in the same year, the projected demand for animal-derived protein will double (3). Current worldwide meat consumption estimates range from 200 to over 300 million tons—by 2050, it may be 600 million tons or more (4, 5).

Most nutritionally-interested people are at least peripherally aware of the sometimes horrific practices of CAFOs—confined animal feeding operations.

“AFOs congregate animals, feed, manure and urine, dead animals, and production operations on a small land area. Feed is brought to the animals rather than the animals grazing or otherwise seeking feed in pastures, fields, or on rangeland. There are approximately 450,000 AFOs in the United States.”

The USDA Census of Agriculture found that the large majority of animal products consumed in the United States were supplied by these confined operations, with the largest operations located in California, Colorado, Georgia, Mississippi, the Carolinas, Arizona, and New Mexico (6).

The wastewater and manure produced by CAFOs are regulated by the Environmental Protection Agency. However, they contain contaminants such as excessive nitrogen and phosphorus,  E. coli, growth hormones, cleaning chemicals, animal blood, and copper sulfate that invade ground and surface water.

Air pollutants are also an issue as CAFOs release ammonia, hydrogen sulfide, methane, and particulate matter that negatively affect nearby residents’ health and property values (7).

But these pollutants do more than create local health problems—they lead to ecological trouble, as well.

“Globally, livestock operations are responsible for approximately 18% of greenhouse gas production and over 7% of U.S. greenhouse gas emissions (Massey & Ulmer, 2008). While carbon dioxide is often considered the primary greenhouse gas of concern, manure emits methane and nitrous oxide which are 23 and 300 times more potent as greenhouse gases than carbon dioxide, respectively. The EPA attributes manure management as the fourth leading source of nitrous oxide emissions and the fifth leading source of methane emissions (EPA, 2009)” (7).

So what about plant-based proteins, like cereal grains and pulses? Or alternative proteins, like insects?

A 2017 paper from researchers in Ireland explored these options, along with algae, seaweeds, and in-vitro meat. One interesting point made by the authors was the fallacy of assuming a more positive environmental impact from alternative protein sources. While grain and pulse production contribute less greenhouse gas emissions compared to concentrated animal farms, criticisms include excessive water use, soil degradation, and air, water, and soil pollution (8).

Insects offer a much smaller environmental footprint and are high in easily digestible protein. However, most Westerners don’t consider insects food and might be reluctant to accept them as a menu item. China, the Philippines, and parts of Europe are experimenting with industrial-scale insect production. But the systems needed to support the industry are still extremely expensive.

From a personal perspective, I grew up in a family of industrial crop producers in Western Kentucky. The main crops were soybeans, corn, and winter wheat. As a child, I was warned not to touch soybeans pre-treated with fungicide and insecticide due to health risks.

While my family has done their best to increase the quality of the farm’s soil, they regularly use glyphosate, atrazine, and paraquat. Additionally, because they farm in the Ohio River watershed, regular flooding distributes these chemicals throughout the river basin, into the Mississippi River approximately 40 miles southwest, and eventually, the Gulf of Mexico.

From the research I’ve read, the magnitude of effect of animal farms is immense, but in an indirect and somewhat relative way due to their reliance on agriculture.

38-50% of the Earth’s viable land (excluding deserts or land covered by ice) is dedicated to agriculture. And while some of the crops are eaten by humans, 77% of farmed land is dedicated to grazing or crops eaten by animals (9).

However, according to the U.S. Environmental Protection Agency, agriculture, including CAFOs and intensive plant farming, only account for 11% of the world’s greenhouse gas emissions.

We can’t forget the serious problems of polluted surface and groundwater and soil. However, from a big-picture perspective, agriculture contributes only a small part to the climate crisis.

This isn’t to say that industrial farming is a healthy practice—far from it. Instead, it’s one that should be viewed in context when we discuss climate change. Based on greenhouse gas contributors, eating as local as possible is the most impactful decision we can make.

This brings us to the final point of the sustainability and ethics of increased protein consumption: food access. Protein is expensive, and for many people, it’s simply not accessible. This is especially true for those most affected by food apartheid, the term farmer and activist Karen Washington coined to better describe the more popular terminology “food desert.”

“Oftentimes, people use the words “food desert” to describe low-income communities who have limited access to food. In fact, we do have access to food—cheap, subsidized, processed food. The word “desert” also makes us think of an empty, absolutely desolate place. But there is so much life, vibrancy, and potential in these communities. I coined the term “food apartheid” to ask us to look at the root causes of inequity in our food system on the basis of race, class, and geography. Let’s face it: healthy, fresh food is accessible in wealthy neighborhoods while unhealthy food abounds in poor neighborhoods. “Food apartheid” underscores that this is the result of decades of discriminatory planning and policy decisions. It begs the question: What are the social inequities that you see, and what are you doing to address them” (10)?
– Karen Washington

Outside of the United States, in countries such as India and Ethiopia, meat availability, specifically, is sparse. And when compared to meat availability across the globe, the United States has two times more access (11).

So while meat is an essential nutrient-dense food source in developing countries, and animal ownership is often a way out of poverty, it’s generally difficult to obtain. Comparatively, it’s much easier to access in the United States, but mainly for those with more resources.

To add to this conversation, only 42,926 out of 1,911,859 farms in the United States were operated by non-white or Hispanic people, representing about 3 percent of farms with livestock or livestock sales (12). But the adverse effects of CAFOs, including odor plumes that can spread for miles, primarily affect minorities (13).

The ideal situation is to support small, local, sustainably run animal farms that employ intensive grazing practices. These farms produce meat that is healthy for us and the environment. Their very existence decreases the effects of pollution and climate change thanks to carbon sequestration and soil rebuilding. But this option represents what is possibly the least accessible source of meat for most people in the United States.

This is not an easy issue to reconcile, but one that demands our attention.

Can an increase in women’s protein requirements negatively impact health?

In the first blog, we discussed lifespan (how long one lives) versus healthspan (how functionally one lives), which is rarely considered by those who promote a low-protein diet.

But a more direct approach would be to investigate the possible negative effects of increasing dietary protein beyond the current RDA of 0.8 g/kg/day.

Multiple studies have examined a high-protein diet’s effect on:

• skeletal health
• renal function
• cancer risk
• liver function
• cardiovascular health
• gastrointestinal health
• overall mortality

But what did the studies find?

Skeletal Health

The health of our bones related to women’s protein requirements is, as one astute author put it, a paradox (14).

As referenced earlier in the blog, we need sufficient dietary protein to reduce the risk of sarcopenia and osteoporosis. These two diagnoses are closely related due not only to muscles’ mechanical action on bone (muscle contraction, growth, and development stimulate bone formation) but also because of the biochemical cross-talk between muscle and bone (15, 16).

“Growing evidence shows that sarcopenia and osteoporosis share many common pathways including the sensitivity to reduced anabolic hormone secretion, increased inflammatory cytokine activity, anabolic or catabolic molecules released by the skeletal muscle or by the bone cells (i.e. myokines and osteokines) and eventually, reduced physical activity [7^▪▪,8]” (16).

Additionally, the structure of bone is approximately 50% protein by volume and about one-third of its mass!

So, where does the paradox come into play?

Some experts have published concerns regarding the effects of higher protein diets on bone health. Factors include:

• the amount of protein in the diet
• protein source
• calcium intake
• weight loss
• acid-base balance of the diet and its effect on plasma pH and bone density

However, the most debated concept is the role of dietary protein in acid-base balance and the downstream effects on bone health.

Some health authorities, such as well-respected naturopath and researcher Joseph Pizzorno and colleagues, have suggested that dietary factors positively or negatively influence our systemic pH. Foods that contain high-sulfur amino acids, such as those in animal proteins (methionine and cystine, specifically) and an excess of sodium chloride in the diet (salt, in any form), contribute to a systemic net acid effect that he calls “low-grade” acidosis (17). Over time, sustained acidosis may contribute to the loss of bone or even muscle mass and the formation of calcium-based kidney stones.

To break this down into more simple terms, what we eat influences the pH of our body, specifically our blood plasma. Animal foods and excessive salt can lead to an acidic pH state, while fruits, vegetables, and other plant foods, particularly those with high amounts of potassium, contribute to a basic pH state.

However, not all nutrition scientists agree, and some even go so far as to “de-bunk” the acid-base hypothesis described above. They cite evidence that higher-protein diets, even those with hearty amounts of animal foods, seem to increase bone mineral density and reduce the risk of fractures (18).

“Although it is believed that there is no risk of adverse effects when healthy people consume high-protein diets, the lack of long-term human studies should be considered.⁶⁰ Glomerular filtration rate of the kidney rises after protein consumption is increased,⁶¹ but this response declines with age. However, although it is a fact that higher protein intakes are harmful to individuals with existing kidney dysfunction, there is little supportive evidence that it is dangerous to generally healthy individuals^60,61 ” (18).

After reviewing multiple reviews and primary studies presenting different interpretations of the acid-base hypothesis, it seems prudent to return to one core nutritional foundation: balance.

So much excellent evidence shows multiple positive effects of increasing women’s protein requirements. However, this increase needs to be accompanied by a wide array of colorful vegetables and fruits, fiber-rich legumes and grains, as tolerated, nuts and seeds…in short, a balanced, nutrient-rich diet with an awareness of moderate salt intake, a point we’ll discuss more in the third part of this blog series.

There may be some outlying cases where the benefits of a primarily animal-food-based diet outweigh the documented risks, such as those who report the resolution of autoimmune symptoms with the carnivore diet. But for the large majority of the population, a balance of animal and plant foods, with a focus on approximately one gram of protein per pound per day, is a good recipe for functional health.

Kidney Function

Thankfully, there is more consensus on the effect of a higher protein diet on renal function.

While it was once thought that an increased amount of dietary protein was detrimental to kidney health, most research now agrees that this is only the case for those with impaired kidney function (19).

The consideration that high protein was harmful to renal health originated from animal studies and extrapolation of data from studies on the effects of protein in people with kidney disease to those without kidney disease. Another factor that contributed to this supposition was the changes that occurred in the kidneys when dietary protein is increased (20).

The kidneys do adapt to a high-protein diet. They can increase in size, and glomerular filtration rate, or GFR, the main indicator of kidney function, increases after a protein-rich meal.

• “An increased GFR occurs physiologically after consuming a high-protein meal and during pregnancy

• Increased GFR can occur as an early manifestation of disease, for example in diabetes mellitus, but it remains to be proven whether glomerular hyperfiltration is a precursor of chronic kidney disease” (21)

However, these changes aren’t necessarily indicative of disease. For instance, GFR also increases in pregnancy…and it increases a lot. GFR can rise up to 65% higher in pregnant versus non-pregnant people! However,  pregnancy is not a risk factor for developing kidney disease. And based on what we currently know, neither is a robust intake of dietary protein.

But it would be irresponsible to think that protein is not without risk for some people, however.

Women’s protein requirements for those with hypertension, kidney disease, or possibly even a predisposition to kidney disease or kidney stones should be adjusted accordingly. Be sure to investigate family history, along with blood markers such as eGFR, creatinine, BUN, sodium, potassium, chloride, and carbon dioxide.

Cardiovascular Health

The relationship between women’s protein requirements and cardiovascular health is a return to the controversial, as evidenced by the initial results from our research:

Let’s take a closer look.

In one rodent study, a higher protein (but also high fat) diet was found to contribute to atherosclerotic plaques and inhibit mitochondrial physiology, specifically mitophagy, the process of recycling old or damaged mitochondria (22). The amino acid leucine, high in chicken, beef, pork, tuna, tofu, navy beans, and whey, was an especially strong contributor to unstable atherosclerosis.

But a 2009 observational study of healthy people presents a more complex story.

Participants who ate a high-protein diet (in women, 2.88 g/kg/day, or approximately 220 grams per day for a 170 lb woman) had higher rates of cardiovascular events when compared to those who ate moderate amounts of protein (1.10 to 1.38 g/kg/day, or 106 grams per day for a 170 lb woman).

However, the highest rates of cardiovascular events occurred in those who ate the least amount of protein, 0.39 to 0.96 grams per day.

Remember, the RDA for protein is 0.8 g/kg/day.

Interestingly, those in the group who ate the most protein had the lowest rate of all-cause mortality.

But those with the best overall cardiovascular and mortality outcomes were in the moderately high group, with intakes of approximately 1.22 to 1.38 grams per day (23).

Even more intriguing is a 2013 review of whey protein, a commonly used protein powder particularly high in the amino acid leucine, mentioned in the mouse study, above.

The authors found that whey protein was beneficial not only for blood sugar and insulin levels but also for heart health:

“In addition, whey protein has been shown to improve glucose levels and insulin response, promote a reduction in blood pressure and arterial stiffness, and improve lipid profile. The collective view of current scientific literature indicates that the consumption of whey protein may have beneficial effects on some symptoms of the metabolic syndrome as well as a reduction in cardiovascular risk factors” (24).

Other types of protein that are particularly good for the heart are fish, poultry, nuts, seeds, eggs, and soy. These foods are linked to more robust cardio health than processed red meats, for instance (25). Even large amounts of fresh red meat, specifically in people with high iron or ferritin, should be eaten with awareness. Remember: it’s all about balance.

Gastrointestinal Health

The digestive system is possibly the most crucial area of the body to be aware of when increasing women’s protein requirements.

Specifically, the microbiome of the large intestine.

Because we aren’t able to digest 100% of the food we eat, some of it ends up in our intestines and is then “digested” by resident bacteria, fungi, protozoa, and viruses that make up a balanced microbiome. In turn, these microbes release their own waste products.

Years of research point toward a great benefit to the microbiome from ingesting fibrous plant foods. When our gut bugs eat fiber, they create compounds that keep our gut (and body) healthy, such as the short-chain fatty acids butyrate, propionate, and succinate. Thanks to these metabolites, our gut barrier remains stable, much-needed mucus production remains plentiful, and our levels of inflammation and subsequent risk of colon cancer remain low (26).

However, the microbial metabolites created from protein fermentation are a different story.

Unfortunately, these byproducts, such as branched-chain fatty acids, phenols, indoles, ammonia, amines, hydrogen sulfide, and thiols are known carcinogens, mutagens, and cellular toxins. And they’re associated with everything from inflammatory bowel disease to colon cancer (27).

Until now, the information I’ve presented on increasing dietary protein has been largely positive—improved immunity, better pregnancy prep and recovery, and more muscle mass equating to a stable body and sustained function throughout the lifespan.

But the effects on the GI have to be seriously considered, especially for those with a history of digestive distress.

So, what do you do?

Thankfully, our diets aren’t composed of just one set-in-stone macronutrient. What we eat with protein, the type of protein we eat, and the way it’s prepared all contribute to its effect on our gut and systemic health.

Eating more protein also means we must create balance with more fibrous plant foods. Great choices are:

• resistant starches such as rice, plantains, potatoes, oats, and green bananas
• prebiotic-rich foods such as onions, garlic, leeks, Jerusalem artichokes, and burdock
• antioxidant-rich foods such as herbs and spices like clove, berries, well-sourced and fermented dairy, and a full array of colorful veggies and fruits

And remember, protein is not all bad when it comes to the gut.

A fantastically balanced 2017 review from researchers in France on the impacts of protein on inflammatory bowel disease states:

“For instance, although the dietary protein needs for mucosal healing after an inflammatory episode remain undetermined, there is evidence that amino acids derived from dietary proteins display beneficial effects on this process, serving as building blocks for macromolecule synthesis in the wounded mucosal area, energy substrates, and/or precursors of bioactive metabolites. However, an excessive amount of dietary proteins may result in an increased intestinal production of potentially deleterious bacterial metabolites” (28).

So, while it may seem like a GI villain, protein also plays a role in gut healing. But it must be balanced with other macros and fibers for us to enjoy its benefit.

More on women’s protein requirements…

In part 3 of this blog series, we’ll discuss optimal dietary protein intake in special populations such as pregnant and lactating people, children, those with connective tissue disorders, perimenopause and menopause, and those who eat the Carnivore diet.