Understanding if there is anything wrong with protein shakes

October 12, 2025 •

4 min read

According to a report by the Clean Label Project, some protein powders have been found to contain heavy metals, pesticides, and other toxins. This finding highlights a core concern for consumers wondering: is there anything wrong with protein shakes? The answer is nuanced, depending on ingredients, dosage, and individual health.

Quick Summary

Protein shakes are not inherently harmful for healthy individuals, but risks exist related to heavy metal contamination, digestive issues, and high sugar content. Moderation and choosing third-party tested products are key to safe consumption.

Key Points

Check for third-party certification: Since the FDA doesn't strictly regulate supplements, look for seals from organizations like NSF International to ensure products are tested for contaminants like heavy metals.
Choose the right protein source: Opt for whey protein isolate or plant-based proteins if you have lactose intolerance or a dairy allergy to avoid digestive discomfort like bloating and gas.
Limit added sugars and fillers: Read labels carefully to avoid protein powders with excessive artificial sweeteners, fillers, and added sugars that can contribute to digestive issues and weight gain.
Don't replace whole foods: Use protein shakes as a supplement to fill nutritional gaps, not as a replacement for balanced meals rich in fiber, vitamins, and minerals from whole foods.
Understand kidney health: While high protein intake is unlikely to harm healthy kidneys, individuals with pre-existing kidney disease must consult a doctor, as excess protein can worsen their condition.
Monitor intake for weight management: Be mindful of the calorie content in protein shakes, as adding them on top of a normal diet without extra activity can lead to unintended weight gain.

Protein Shakes: Separating Fact from Fiction

Protein shakes have become a ubiquitous part of modern wellness culture, moving from the niche world of bodybuilding to the mainstream. While their convenience and effectiveness for muscle growth and satiety are well-documented, concerns about their safety persist. The question, "is there anything wrong with protein shakes?" warrants a closer look at the potential drawbacks and how to mitigate them.

Contaminants in Unregulated Supplements

One of the most significant issues with protein powders is the lack of strict regulation by entities like the FDA. This can lead to a risk of contamination with harmful substances. A 2022 study by the Clean Label Project found that many protein powders contained heavy metals such as lead, arsenic, and cadmium, along with BPA and pesticides. These toxins can accumulate in the body over time. The primary takeaway for consumers is to seek out products that have been third-party tested and certified by organizations like NSF International or Informed-Sport to ensure purity and label accuracy.

Potential Digestive Issues

For many, the most immediate downside of protein shakes involves digestive discomfort. These issues are often linked to the type of protein or other ingredients in the shake:

Lactose Intolerance: Whey and casein proteins are derived from milk and contain lactose. For the estimated 65% of the global population with lactose intolerance, consuming these can lead to gas, bloating, cramps, and diarrhea.
Artificial Sweeteners and Additives: Many flavored protein powders contain artificial sweeteners like sucralose or sugar alcohols such as erythritol, which can cause bloating and a laxative effect. Thickeners and fillers can also contribute to digestive distress.
High Protein Load: Consuming very large amounts of protein in a single sitting can tax the digestive system, regardless of the source. Spacing out protein intake throughout the day can alleviate this.

Overburdening the Kidneys and Liver

The long-standing myth that high protein intake damages the kidneys in healthy individuals is largely debunked by recent research. Studies show that the increased kidney activity that occurs with high protein consumption does not cause harm in people with normal kidney function. However, this is not true for everyone. Individuals with pre-existing kidney or liver disease must monitor their protein intake carefully, as excess protein can exacerbate their condition. It is always crucial for those with underlying health issues to consult a doctor before starting supplementation.

Nutritional Imbalance and Weight Gain

Replacing whole-food meals with protein shakes can lead to a nutrient imbalance. Shakes lack the fiber, vitamins, and antioxidants found in whole foods like fruits, vegetables, and legumes. A high-protein, low-fiber diet can also contribute to constipation. Furthermore, some protein shakes are loaded with added sugars and calories, which can lead to unwanted weight gain if not accounted for in overall daily caloric intake. A protein shake should be a supplement to, not a replacement for, a balanced diet.

Animal vs. Plant-Based Protein Powders


Feature	Animal-Based (Whey, Casein)	Plant-Based (Pea, Hemp, Soy)
Source	Milk, eggs, collagen	Soybeans, peas, hemp seeds, brown rice
Completeness	Complete protein source with all essential amino acids.	Individual plant sources may be incomplete; blends often form a complete protein.
Lactose Content	Whey contains some lactose; isolate has less. Not suitable for lactose intolerant or dairy-allergic individuals.	Generally dairy-free and suitable for vegans and those with lactose intolerance.
Fiber Content	Low in fiber.	Higher in fiber, which aids digestion and promotes satiety.
Digestion Speed	Fast-digesting (whey) or slow-digesting (casein), often well-absorbed.	Absorption rates can vary; generally slower than whey.
Potential Issues	Lactose intolerance, dairy allergies, potential contamination.	Potential for grainier texture; soy can be an allergen for some.

The Importance of a Balanced Approach

Protein shakes are a tool, not a magic bullet. They are most beneficial when used strategically by athletes with high protein needs, older adults trying to combat muscle loss, or those with certain medical conditions like difficulty chewing. For the average, healthy person, adequate protein can usually be obtained through a diet rich in whole foods without the need for supplements. A balanced diet should always be the foundation of a healthy lifestyle.

Conclusion: Responsible Use is Key

So, is there anything wrong with protein shakes? There can be, but many potential issues are avoidable with conscious choices. Contamination risks, digestive problems, and nutritional gaps are valid concerns. However, by selecting third-party certified products, being mindful of your specific dietary needs and sensitivities, and using protein shakes as a supplement to a balanced diet rather than a replacement for whole foods, they can be a safe and convenient tool. The key is to prioritize real food sources and use shakes with moderation and awareness. For specific medical conditions or high athletic demands, consulting a doctor or registered dietitian is the safest path. Healthline provides more detail on protein shake safety.

Frequently Asked Questions

For individuals with healthy kidney function, research suggests that consuming protein shakes in moderation will not cause damage. However, those with pre-existing kidney disease should monitor their protein intake and consult a doctor, as excess protein can put extra strain on the kidneys.

Yes, they can. Digestive issues like bloating, gas, and cramps often occur in people with lactose intolerance consuming milk-based protein powders. Artificial sweeteners and fillers found in some products can also upset the stomach.

Yes, studies have found some protein powders contain heavy metals, pesticides, and other toxins due to manufacturing processes. To minimize this risk, choose products that are third-party certified by reputable organizations.

Protein shakes contain calories, and if you consume them in addition to your normal diet without increasing your physical activity, you may gain weight. For weight loss, they can be used strategically to increase satiety and help meet protein goals within a calorie deficit.

For those with dairy allergies or lactose intolerance, plant-based proteins like pea, rice, or hemp can be easier to digest. They also often contain more fiber than whey protein.

While protein shakes are convenient, they should not regularly replace whole-food meals. Whole foods provide a wider array of essential nutrients, fiber, and vitamins that are often missing from shakes. Using them as a supplement or occasional meal replacement is acceptable.

Look for a product with third-party certification (e.g., NSF or Informed-Sport) to verify its contents. Check the ingredient list for minimal additives, low added sugars, and a protein source that aligns with your dietary needs and sensitivities.