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Collagen vs. Whey: Pros, Cons & What To Look For In Your Supplement

Kirsten Nunez, M.S.
Author: Expert reviewer:
December 15, 2021
Kirsten Nunez, M.S.
Contributing writer
By Kirsten Nunez, M.S.
Contributing writer
Kirsten Nunez is a health and lifestyle journalist based in Beacon, New York. She has a Master of Science in Nutrition from Texas Woman's University and Bachelor of Science in Dietetics from SUNY Oneonta.
Ashley Jordan Ferira, Ph.D., RDN
Expert review by
Ashley Jordan Ferira, Ph.D., RDN
mbg Vice President of Scientific Affairs
Ashley Jordan Ferira, Ph.D., RDN is Vice President of Scientific Affairs at mindbodygreen. She received her bachelor's degree in Biological Basis of Behavior from the University of Pennsylvania and Ph.D. in Foods and Nutrition from the University of Georgia.
December 15, 2021

With so many protein supplements on the market, choosing the best one can feel like an actual lift. This is especially true if you're stuck between collagen and whey, two types of popular protein supplements. On one hand, collagen has become super trendy in the last several years for its laundry list of benefits; on the other, whey is essentially the OG of protein supplements.

Ultimately, the ideal choice depends on your personal goals and what you're looking to get out of supplemental protein. But in order to do that, you'll need to understand the pros and cons of collagen vs. whey and how they compare to each other. 

What is collagen?

Collagen is a family of proteins found in the body's connective tissues. These proteins serve as the main building blocks of bones, muscles, ligaments, joints, blood vessels, and skin, according to Ella Davar, R.D., CDN, registered dietitian and mbg contributor. In fact, about 30% of the body's total protein is made of collagen, making it the most abundant protein1 in humans.

The body can make its own collagen, but this naturally declines over time. Stressors like sun exposure, high-sugar diets2, and smoking tobacco can also further diminish collagen levels. In turn, you might consider adding collagen supplements to your wellness routine. 

Pros of collagen.

Given its role in multiple tissues, collagen works to improve several areas of health:*

  1. Skin health. Collagen is a top-tier supplement in the world of skin care. After all, collagen is responsible for not only the skin's structure but its elasticity and stretchiness as well, notes Davar.* That said, the natural age-related decline in collagen3 can gradually lead to skin changes like wrinkles, fine lines, and dryness. Fortunately, collagen supplements can help, as determined by a scientific review of 11 studies with more than 805 participants, which found that oral collagen supplements can enhance skin hydration and elasticity4.* 
  2. Bone health. The age-related dip in collagen affects more than your skin. "Naturally bones become less dense and thus, less strong," says Davar. An important, long-term clinical study found that postmenopausal women showed enhanced bone density5 at 12 months after consuming collagen peptides daily for a year.*   
  3. Muscle development. Collagen is not a complete protein, meaning it doesn't contain all nine essential amino acids the body needs. But it does contain eight of those nine, so it can certainly support muscle development, especially when combined with a balanced diet and exercise.* In fact, one study found that you can meet your daily amino acid needs if 36% of your protein intake6 is comprised of collagen peptides. A small clinical study7 also found that men who took daily supplemental collagen and followed a strength training program gained more muscle mass than those who followed the program without taking collagen.* 
  4. Gut health. Taking collagen can also help your gut health journey, in conjunction with a well-rounded lifestyle.* Collagen contains glycine8 and glutamine9, two amino acids with anti-inflammatory properties and has been shown to support gut health10.* Glutamine, in particular, is a preferred source of energy for intestinal cells9.*  
  5. Dairy-free. Depending on the brand, collagen supplements are made from the connective tissue of fish, cows, or chickens. They aren't derived from milk, so they're naturally dairy-free and lactose-free. This means supplemental collagen is ideal for people who are allergic to dairy, lactose intolerant, or simply prefer to skip milk products.
  6. Minimal taste and odor. Compared to whey, collagen is less likely to have a pungent taste or smell. As Davar notes, collagen is practically odor-free and easy to consume, even if it's unflavored. This makes it ideal for a range of recipes, including baked goods, lattes, and even margaritas

Cons of collagen.

There are some downsides and side effects of collagen. These include: 

  1. Incomplete protein. To recap, collagen is not technically a complete protein. As mentioned earlier, this isn't necessarily a disadvantage, as the 18 plus amino acids in collagen can still significantly contribute to your daily protein intake. However, if you're specifically looking for a complete protein supplement, collagen won't fit the bill.  
  2. Fish allergens. If you're allergic to fish or shellfish—two of the most common food allergens11—you'll need to be extra diligent when buying collagen. That's because collagen supplements can be made from marine sources, in addition to cows and chickens. Some brands may even use a combination of both. Thus, if you have a fish or shellfish allergy, use caution when choosing collagen products.
  3. Stomach upset. Stomach upset is an anecdotal side effect of consuming collagen. However, this side effect is uncommon and likely linked to brand formulas rather than collagen itself. 

What is whey protein?

Whey protein12 is one of the two proteins in milk; the other is casein. Basically, when milk is made into cheese, the watery liquid (called whey) separates from the solid curds. Whey contains whey protein, which can be used as a protein supplement. 

Pros of whey.

Here's why you may want to purchase whey:

  1. Complete protein. If you're looking for a complete protein supplement, whey protein will check all your boxes. That's because it contains all nine essential amino acids the body needs but can't make on its own. 
  2. Fast absorption. "Whey protein is absorbed faster13 than other proteins," says Sandy Younan Brikho, MDA, RDN, registered dietitian and founder of The Dish on Nutrition. This is true even compared to casein, which is also found in milk. So much so that whey has been dubbed as a "fast" protein14, as it takes just one hour to absorb 10 grams of whey protein. 
  3. Muscle development. Between its complete protein content and fast absorption rate, whey protein is excellent for building muscle mass. According to Brikho, it's especially high in the branched-chain amino acid leucine15, which serves as the body's primary nutritional signal for triggering muscle protein growth. Leucine also "decreases muscle soreness and muscle fatigue," adds Brikho. As a result, whey protein is the go-to supplement for many athletes. 

Cons of whey.

Though whey is a complete protein, it has numerous shortcomings:  

  1. Dairy and lactose content. Since whey protein comes from milk, it's not ideal for individuals who have a dairy sensitivity or allergy. (Dairy is one the most common food allergens, BTW.) The same goes for those with lactose intolerance, which affects a whopping 68% of people in the world. 
  2. Stomach upset. If you're sensitive to dairy, whey protein may cause "digestive problems such as irregularity, loose stools, or queasiness, especially [when taken in] large amounts," says Davar.  
  3. Blemishes. Whey protein may cause skin changes like blemishes in some folks. The exact cause is unknown, but researchers think it's related to the hormonal effects of dairy. Specifically, this includes increased levels of insulin-like growth-hormone-1 (IGF-1), which may have a comedogenic (pore-clogging) effect on the skin.
  4. Bad taste and smell. Whey protein is commonly associated with an unpleasant taste and odor. According to Davar, the taste is often described as bitter with an aftertaste, while the smell is like cardboard or wet paper with milky notes. Whey protein hydrolysates, in particular, may be associated with a sour cheese-like smell. On that note…
  5. Sweeteners and flavors. Due to the unpleasant flavor and smell of whey protein, most people (unsurprisingly) prefer flavored versions, says Davar. Unfortunately, these products often contain artificial sweeteners and flavorings, she adds.

How to find a quality supplement.

When choosing a supplement of any kind, keep these factors in mind:

  • Delivery method. Consider functionality and versatility, as these characteristics will allow a supplement to be seamlessly added to your wellness routine. Specifically, when picking collagen supplements, powders are ideal because they offer substantial and useful doses of protein in a convenient form. 
  • Brand transparency. Look for a brand that willingly shares info about their manufacturing and quality testing processes. It should be easy for the consumer (that's you!) to assess proof of purity, says Davar. 
  • Sourcing. To ensure your supplements contain safe and high-quality ingredients, Brikho suggests choosing a product that has undergone third-party potency and purity testing. This quality testing ensures that the active ingredients are included at the doses mentioned on the label and that contaminants like yeast, mold, bacteria, heavy metals, and pesticides are absent or kept to an allowable minimum per the law. 
  • Extra ingredients. "Some unscrupulous producers [may] use fillers that aren't listed on the label," explains Davar. However, choosing a product that has been tested for quality parameters like purity will help you avoid unwanted ingredients. Similarly, if you have any allergies, double-check the label to ensure it's safe for you to take. All major food allergens are required by supplement law to be listed on the label.

Finally, "speak to your doctor before supplementing anything," says Brikho. In the case of collagen, "it could interfere with certain medications and supplements, which could have side effects," she notes. 


For most people, collagen is the superior choice, as it's less likely to cause side effects like digestive issues and skin changes. It also doesn't hurt that it can enhance multiple areas of health. If you're still stuck between collagen vs. whey, talk to a doc or registered dietitian for personalized guidance.

If you are pregnant, breastfeeding, or taking medications, consult with your doctor before starting a supplement routine. It is always optimal to consult with a health care provider when considering what supplements are right for you.
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