Dr. Thomas Dwan - Is It Bad For You? Approved by Dr. Thomas Dwan

Is Protein Bad For You?



Short answer

Protein is essential for numerous bodily functions and muscle maintenance, but sources and amounts determine its health impact. Animal proteins, complete with all amino acids, may contain contaminants like hormones, while plant proteins offer fiber and biochemical benefits. Excess protein intake poses risks, particularly for kidney function and heart disease. A balanced diet with a variety of protein sources is recommended for optimal health.



Long answer

The Role of Protein in Body Function and Muscle Maintenance

Protein is more than just a dietary buzzword — it is a fundamental component of a healthy diet and plays an indispensable role in numerous bodily functions. Understanding the multifaceted capabilities of this macronutrient is crucial for appreciating its significance in our diet and ensuring we're consuming it in appropriate amounts for optimal health.

1. Cell Structure and Function: Proteins are the building blocks of life, involved in the creation and repair of cells. Structural proteins, such as collagen and elastin, are key to the fabric of our connective tissues, providing strength and elasticity. Functional proteins, including enzymes and hormones, are pivotal in carrying out biochemical reactions that contribute to digestion, energy production, and the regulation of blood sugar and metabolism.

2. Muscle Growth and Repair: One of the most recognized roles of protein is in the development and maintenance of muscle mass. Dietary proteins are broken down into amino acids, which are then used by the body to synthesize new proteins in a process known as protein synthesis. This process is especially important after exercise, as muscles undergo repair and growth in response to the controlled damage inflicted by physical activity. Without adequate protein, the body cannot effectively repair and build muscle tissue.

3. Immune System Support: Antibodies, which are essential for immune response, are made of protein. They help to protect the body against pathogens by recognizing and binding to antigens, which are foreign bodies like viruses and bacteria, rendering them harmless.

4. Transport and Storage: Proteins such as hemoglobin and myoglobin serve as carriers and storehouses for essential substances. Hemoglobin in red blood cells binds to oxygen, delivering it throughout the body, while myoglobin in muscle cells stores oxygen for use during physical activity.

5. Nutrient Balance: Albumin and globulin proteins maintain the body’s fluid and pH balance while also transporting nutrients such as vitamins, minerals, and fats through the bloodstream.

6. Muscle Energy Reserve: During prolonged periods of exercise or in situations where carbohydrates are scarce, the body can use protein as an energy source. However, this is not the body's preferred energy source and occurs under starvation or ketogenic conditions.

Evidence-Based Perspective: Scientific studies continually reinforce the necessity of protein for muscle maintenance. For instance, research published in the American Journal of Clinical Nutrition demonstrates a clear link between protein intake and muscle mass retention, especially among older adults. Furthermore, a meta-analysis in the Journal of the International Society of Sports Nutrition illustrates the benefits of protein supplementation on muscle hypertrophy and strength in individuals engaged in resistance training activities.

Conclusion: The role of protein in the body extends well beyond muscle maintenance; it is pivotal for the overall structural and functional integrity of our cells and systems. Our muscular system, while a prominent beneficiary of protein, is just one of the many recipients of this macronutrient's wide-ranging effects. As we look at our diets and consider our protein sources, it's essential to remember the full spectrum of protein's roles and the robust evidence supporting its necessity in maintaining health and well-being.

Protein Sources and Potential Contaminants

Protein can be derived from various sources, each with its distinct nutritional profile and potential risks. Animal-based proteins, such as meat, dairy, and eggs, provide essential amino acids required for the body's functioning. Plant-based proteins, including legumes, nuts, and seeds, offer additional fiber and phytonutrients but may require careful combination to ensure a complete amino acid profile.

However, the discussion doesn't end at nutritional content. Both sources can harbor contaminants that pose health risks:

  • Heavy Metals: Certain plant-based proteins, especially those in powder form like rice or pea protein, can accumulate heavy metals from soil and water contamination. Long-term exposure to heavy metals, such as lead, mercury, and arsenic, can lead to serious health issues.
  • Hormones and Antibiotics: Animal-based proteins may contain hormones and antibiotics that have been used to promote growth and prevent disease in livestock. These substances can disrupt human hormone balance and contribute to antibiotic resistance.
  • Pesticides: Non-organic sources of both plant and animal proteins might contain pesticide residues. Pesticides have been linked to a variety of health problems, including endocrine disruption and cancer.
  • Artificial Additives: Processed protein sources often contain artificial flavors, colors, and preservatives, which can have adverse effects on health, particularly when consumed in large quantities over time.

Let's delve deeper into the specifics:

Protein Source Potential Contaminant Health Concerns
Plant-Based Powders Heavy Metals Neurotoxicity, Kidney Damage
Commercial Meat Hormones & Antibiotics Hormonal Imbalance, Antibiotic Resistance
Non-Organic Produce Pesticides Endocrine Disruption, Carcinogenic Risk
Processed Foods Artificial Additives Allergic Reactions, Behavioral Issues

To minimize the risks associated with these potential contaminants, consider the following strategies:

  • Select organic sources of protein when possible to reduce exposure to pesticides and synthetic substances.
  • Opt for grass-fed or pasture-raised animal products to avoid hormones and antibiotics.
  • Look for third-party tested plant-based proteins that certify low levels of heavy metals.
  • Limit intake of heavily processed proteins with long lists of artificial ingredients.

Research indicates that the health impacts of protein sources can be significant. Studies have found associations between heavy metal exposure from certain protein supplements and adverse health effects. For example, a study published in the Journal of Nutrition and Metabolism (2018) cautioned about the presence of heavy metals in plant-based protein powders and the potential implications for health.

When it comes to animal-based proteins, a review in the journal Frontiers in Public Health (2019) highlighted the potential public health risks of using antibiotics in animal agriculture, particularly the contribution to antibiotic resistance.

Considering these factors is critical for those who rely on high-protein diets and supplementation. An informed approach to protein source selection can help mitigate the risks associated with potential contaminants typically found in various protein options.

Excess Protein Intake: Kidney Function and Bone Health

Protein is a critical macronutrient vital for many bodily processes, including cell repair, immune function, and muscle growth. However, the mantra 'more is better' does not always hold true, especially when it comes to protein intake. It's imperative to understand the impact of excess protein on kidney function and bone health, and the word 'excess' here refers to intake well above the recommended dietary allowance.

Firstly, let's dissect the notion that a high-protein diet may be detrimental to kidney function. The kidneys are responsible for filtering waste products from the blood, including the byproducts of protein metabolism such as urea. Consuming an excessive amount of protein over a prolonged period can increase the metabolic load on the kidneys, potentially accelerating the decline of kidney function in individuals with pre-existing kidney disease.

A number of studies have explored this relationship. For example, a study published in the American Journal of Kidney Diseases found that individuals with mild kidney dysfunction could exacerbate their condition with excessive protein intake. However, it's critical to note that in individuals with healthy kidney function, a high-protein diet has not been conclusively proven to cause kidney damage. Thus, it is those with compromised kidney health or a predisposition to kidney disease who should be cautious about overconsuming protein.

When it comes to bone health, the interaction with protein intake is somewhat counterintuitive. There's long been a hypothesis that a higher protein intake could lead to calcium leaching from bones, thus increasing the risk for osteoporosis. However, current evidence suggests that protein works synergistically with calcium to improve bone health, as indicated by a review in the Journal of Nutrition. In fact, dietary protein may enhance the absorption of calcium and support the bone remodeling process.

That said, the source and type of protein, as well as the overall diet context, matter greatly. An imbalance between acid-producing and alkaline-based foods (with excess protein purportedly being acid-producing) could potentially tip the scales toward calcium excretion. But in the landscape of prevailing evidence, the consensus tilts towards the bone-protective role of adequate protein intake rather than the contrary.

It's undeniable that nutrition is a tweaked symphony rather than a solo performance. Therefore, while considering protein intake, it is not just about the quantity but also the quality and supporting nutrients. Here's what to keep in mind:

  • Aim for a balanced intake of macronutrients.
  • Choose high-quality protein sources that are rich in essential amino acids.
  • Ensure adequate dietary calcium and vitamin D to support bone health.
  • Maintain hydration, as fluids can help mitigate the increased renal load from metabolizing protein.
  • Individuals with kidney concerns should consult with healthcare providers to tailor their protein intake appropriately.

In conclusion, excess protein intake should be approached with prudence, especially for those with certain health concerns. Overwhelming though it may be, evidence points toward a nuanced impact on kidney function and bone health, necessitating a judicious and well-informed approach to dietary protein.

Correlation Between High-Protein Diets and Heart Disease

When examining the effects of high-protein diets on heart health, the picture can be as convoluted as it is contentious. A high intake of protein, particularly from certain sources, has been linked to various cardiovascular outcomes. To fairly assess these connections, it's crucial to dissect the layers of research and identify the nuances that influence heart disease risk. Let's delve into the scientific findings that piece together this complex puzzle.

Firstly, it's necessary to distinguish between protein sources. Evidence suggests that the type of protein—animal or plant-based—matters significantly when considering heart health. A study published in the American Journal of Epidemiology found that higher intake of red meat and high-fat dairy products, both rich in saturated fat and dietary cholesterol, was associated with increased risk of coronary heart disease (CHD). Conversely, plant-based proteins, such as those from legumes and nuts, have been linked to a lowered risk of CHD.

Let's put this under the microscope:

  • Saturated Fats: Proteins high in saturated fats are commonly seen in processed meats and full-fat dairy products. These fats can increase low-density lipoprotein (LDL) cholesterol, often dubbed the 'bad' cholesterol, potentially leading to plaque buildup in the arteries.
  • Sodium: Many high-protein processed foods are also laden with sodium, which in excess, exacerbates hypertension, a risk factor for heart disease.
  • Red and Processed Meats: Consumption of these protein sources has been correlated with higher incidences of CHD, potentially due to compounds such as heme iron and preservatives like nitrates/nitrites.
  • Plant Proteins: These not only avoid detrimental fats and additives but also come packaged with beneficial fibers, antioxidants, and phytochemicals, which collectively contribute to cardiovascular health.

Another dimension to consider is the amount of protein ingested. A meta-analysis in Circulation: Heart Failure concluded that extremely high protein intake, particularly from animal sources, can be associated with an increased risk of heart failure among middle-aged men. Yet, it's not only the quantity but the interplay of protein with other nutrients that frames the risk profile.

Ruminating over the overall diet pattern is key. The acclaimed Dietary Approaches to Stop Hypertension (DASH) and Mediterranean diets, both rich in plant proteins and low in red meat, have repeatedly shown to be heart-healthy. Supporting this, a study in the Journal of the American Heart Association found that higher adherence to a Mediterranean diet, which balances protein intake with an abundance of fruits, vegetables, and healthy fats, correlated with reduced heart disease risk.

In summary, the correlation between high-protein diets and heart disease is not a one-size-fits-all. The quality and source of protein, combined with dietary patterns and lifestyle factors, play an integral role in determining the impact on cardiovascular health. As we continue to unravel this topic, it becomes evident that more than just protein content needs to be examined to safeguard against the specter of heart disease.

Note: The evidence suggests that the adage 'all things in moderation' rings particularly true with protein consumption. Incorporating a variety of protein sources, especially plant-based ones, and paying attention to the company they keep in your overall diet, may be prudent to promote heart health.

Plant vs. Animal Protein: Health Impact and Considerations

When evaluating the health impact of protein sources, it's crucial to distinguish between plant-based and animal-based proteins. Both types of protein can fit into a healthy diet, but they come with different health considerations due to the variety of nutrients they provide, their amino acid profiles, and their effects on health markers like cholesterol and inflammation.

The Amino Acid Profile:
Animal proteins are typically considered "complete" proteins, meaning they contain all nine essential amino acids that the human body cannot produce on its own. In contrast, most plant proteins, with the exception of quinoa and a few others, are "incomplete," lacking one or more essential amino acids. While this might seem like a knock against plant proteins, the body is fully capable of assembling complete proteins, provided a diverse range of plant proteins are consumed throughout the day.

Nutrient Density:
Animal proteins often come with higher amounts of certain nutrients such as vitamin B12, vitamin D, heme-iron, and zinc. On the flip side, plant proteins are usually rich in fiber, antioxidants, and phytochemicals, which are instrumental in reducing the risk of chronic diseases.

Health Markers:
In terms of health markers, studies have shown that diets high in red and processed meats can lead to increased risks of heart disease, type 2 diabetes, and certain types of cancer. On the other hand, plant proteins have been associated with lower levels of cholesterol and a reduced risk of chronic diseases. For instance, a meta-analysis published in The BMJ in 2019 indicated that higher intake of plant-based proteins was associated with lower mortality rates.

Environmental Considerations:
From a sustainability standpoint, plant proteins often have a lower environmental footprint compared to animal proteins. The production of plant proteins usually requires less land, water, and creates fewer greenhouse gas emissions.

Satiety and Weight Management:
Consuming protein can increase the feeling of fullness, which is beneficial for weight management. Animal proteins tend to be more satiating than plant proteins; however, the high fiber content of plant-based proteins can also contribute substantially to satiety.

Animal proteins are typically more easily digested than plant proteins, which may be relevant for individuals with specific dietary concerns or digestive issues. However, proper preparation and cooking of plant proteins can improve their digestibility significantly.

Health Risks of Overconsumption:
With both plant and animal proteins, there is potential for health risks if consumed in excessive amounts. Overconsumption of animal proteins can lead to an increased intake of saturated fats and cholesterol, whereas excessive plant protein intake without sufficient variety could lead to amino acid imbalances.

Ultimately, when considering the health impact and considerations of plant vs. animal protein, balance and variety are key. Including a wide range of protein sources in your diet can help to ensure you get a complete profile of amino acids and other essential nutrients while mitigating potential health risks associated with over-relying on any single source of protein.

Protein Needs: Individual Variability and Overconsumption Risks

Understanding protein needs is crucial because these requirements can differ drastically from person to person. Factors such as age, sex, physical activity level, muscle mass, and overall health play significant roles in determining how much protein an individual needs. While the general Recommended Dietary Allowance (RDA) for protein is 0.8 grams per kilogram of body weight per day for adults, this is simply a baseline.

For example, athletes or those engaged in heavy physical labor may require up to 1.2 to 2.0 grams of protein per kilogram of body weight to support muscle repair and growth. Conversely, sedentary individuals might do just fine with the RDA or slightly above. Elderly adults also have increased protein needs to counteract age-related muscle loss, also known as sarcopenia. Dieticians often tailor protein recommendations to each individual's specific circumstances.

While most people in developed nations easily meet their protein requirements, there is a growing concern about protein overconsumption, particularly with the rise of high-protein diets and supplements. It's essential to recognize the risks associated with consuming too much protein, including:

  • Kidney Strain: Excessive protein can put pressure on the kidneys, potentially leading to long-term damage or exacerbation of pre-existing kidney conditions.
  • Bone Health: High protein intake, mainly from animal sources, has been linked to calcium leaching from bones in some studies, potentially leading to osteoporosis.
  • Heart Disease: Overindulging in red and processed meats, which are rich in protein, is associated with an increased risk of heart disease due to high levels of saturated fats and cholesterol.
  • Weight Gain: Though protein can aid in satiety and weight management, excessive caloric intake from too much protein can result in weight gain.
  • Dehydration: Increased protein can lead to a greater need for water intake to help kidneys flush out the byproducts of protein metabolism.
  • Digestive Issues: In some cases, high protein consumption, particularly from supplements like protein powders, may lead to digestive discomfort or exacerbate pre-existing gastrointestinal issues.

A key study (A. Devries-Aboud et al., Advances in Nutrition, 2015) highlighted the importance of balancing protein intake to optimally repair and rebuild muscle without overburdening the body. The study suggests moderation as the cornerstone of healthy protein consumption.

Moreover, the type of protein consumed matters. The Dietary Guidelines for Americans recommend a variety of protein foods, including seafood, lean meats and poultry, eggs, legumes (beans and peas), nuts, seeds, and soy products. Incorporating a mix of these sources can help mitigate some risks associated with high intakes of processed meat proteins.

Ultimately, individuals considering increasing their protein intake beyond the RDA should do so thoughtfully and, ideally, under the guidance of a nutrition professional. An evidence-based approach that takes into account personal health profiles, lifestyles, and dietary preferences can ensure that protein serves as a supportive nutrient rather than a source of health complications.

Frequently asked questions

Plant-based proteins offer environmental benefits, as their production generally has a lower carbon footprint, requiring less land and water and resulting in fewer greenhouse gas emissions compared to animal-based proteins. Furthermore, they contribute to dietary diversity and can decrease the risk of certain chronic diseases associated with high consumption of red and processed meats, due to the added fiber, antioxidants, and phytochemicals present in plant sources.

Yes, it's absolutely possible to see improvements in muscle mass without relying on protein supplements. Whole food sources of protein, such as lean meats, dairy, eggs, legumes, nuts, and seeds, provide not only the essential amino acids needed for muscle building but also offer a spectrum of other nutrients beneficial for overall health. It's important to ensure that your total daily protein intake aligns with your specific needs, particularly if engaging in resistance training or other forms of exercise that influence muscle hypertrophy.

Yes, the body can process animal and plant proteins differently. Animal proteins are generally more easily digested and absorbed due to their closer resemblance to human proteins. Plant proteins come with fiber and may require more thorough cooking or preparation to improve digestibility. The difference in processing can affect health, as a diet high in red and processed meats has been associated with higher risks of certain chronic diseases, whereas plant proteins are linked to lower cholesterol levels and reduced risk of chronic conditions.

To achieve a complete protein profile on a vegetarian or vegan diet, it's important to consume a variety of plant-based protein sources throughout the day. These can include legumes, nuts, seeds, whole grains, and soy products. Certain plant proteins, such as quinoa and buckwheat, are complete proteins on their own. By combining different plant proteins, such as rice and beans, you can also obtain all the essential amino acids necessary for good health.

Ask a question about Protein and our team will publish the answer as soon as possible.

Possible short-term side effects

  • digestive issues
  • allergic reactions
  • behavioral issues

Possible long-term side effects

  • kidney strain
  • bone health concerns
  • increased heart disease risk
  • hormonal imbalance
  • antibiotic resistance
  • neurotoxicity
  • kidney damage
  • endocrine disruption
  • carcinogenic risk
  • weight gain
  • dehydration

Commonly found in

  • plant-based powders
  • commercial meat
  • non-organic produce
  • processed foods
  • high-protein diets and supplements

Ingredients to be aware of

  • heavy metals
  • hormones
  • antibiotics
  • pesticides
  • artificial additives
  • saturated fats
  • sodium
  • nitrates/nitrites
  • heme iron


  • cell repair and growth
  • immune function
  • muscle maintenance
  • nutrient transport
  • fluid and ph balance
  • energy source during exercise or starvation

Healthier alternatives

  • organic protein sources
  • grass-fed or pasture-raised animal products
  • third-party tested plant-based proteins
  • diverse range of plant proteins
  • mediterranean and dash diet patterns
  • adequate dietary calcium and vitamin d

Thank you for your feedback!

Written by Joey Conners
Published on: 12-08-2023

Thank you for your feedback!

Written by Joey Conners
Published on: 12-08-2023

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