The 6 Best Casein Protein Powders of 2023, According to a Registered Dietitian

Is a Casein Protein Powder Supplement Beneficial?

Protein needs vary based on a number of factors, including age, gender, activity level, and health status. However, most Americans get adequate protein through diet alone—which looks like 46-56 grams of protein per day, or about 0.8 grams of protein per kilogram of body weight. Those who benefit from casein protein powder may include the following:

• Athletes: Many athletes need more protein than the average person due to their high activity level. The additional protein in an athlete’s diet helps support muscle growth and recovery. Because of this, athletes are the main group of people who may benefit from taking a casein protein powder supplement if they cannot get enough protein in their diet.
• Those who prefer protein supplements later in the day: Research shows that consuming milk-based protein after a workout can help promote muscle growth and recovery. Whey protein may be a better option if you want to take your protein supplement right before or after a workout since it gets broken down and absorbed faster than casein. If you prefer to have your protein supplement later in the day or before bedtime, we recommend opting for casein due to its slow absorption rate.

Who May Not Benefit from Casein Protein Powder

These groups may not benefit from taking a casein protein supplement:

• Healthy adults meeting their protein needs through diet: For the average person who is meeting their protein needs with food, a protein powder supplement is not necessary and won’t provide noticeable benefits.
• People on protein-restricted diets: There are certain medical conditions that require a person to eat a low protein diet, including chronic kidney disease and inherited metabolic disorders like phenylketonuria, homocystinuria, maple syrup urine disease, and tyrosinemia. If you need to limit protein in your diet, you should avoid using protein powder in general.
• Older adults: As we get older, we naturally lose muscle mass and strength. One way to combat this is by increasing protein intake as we age, which is particularly effective when combined with resistance training. When it comes to protein supplementation for older adults, faster-absorbing protein sources (like whey protein) may promote muscle growth more effectively than casein, a slow absorbing protein. For this reason, we recommend whey over casein for older adults. You may find it helpful to explore our roundup of the best whey protein powders.
• People with a milk allergy: A milk allergy is an immune system reaction to milk proteins and is treated by avoiding milk and products that contain milk proteins. Since casein is one of the main proteins in milk, those with a milk allergy should avoid using casein protein powder. 
• People on a vegan diet: Casein is an animal-based protein, so it does not fit into a vegan diet. If you are following a vegan diet, choose one of the many types of vegan protein powders instead of casein protein.

How We Select Supplements

Our team works hard to be transparent about why we recommend certain supplements; you can read more about our dietary supplement methodology here. 

We support supplements that are evidence-based and rooted in science. We value certain product attributes that we find to be associated with the highest quality products.

It's important to note that the FDA does not review dietary supplements for safety and effectiveness before they go to market. Our team of experts has created a detailed, science-backed methodology to choose the supplements we recommend.

What to Look For in Casein Protein Powders

Third-Party Testing

 Supplements that are third-party tested are sent to a lab where they are tested to ensure they contain what they say they contain and are not contaminated with specific high-risk, common contaminants. However, it’s important to note:

• Third-party testing does not test to see if a product is effective or safe for everyone, and it does not ensure the supplement will not interact with other supplements or medications.
• Not all third-party testing is created equal. It is not uncommon for supplement companies to pay labs for certificates after conducting minimal to no testing. 
• The third-party certifications we can trust are: ConsumerLab.com, NSF, and USP. However, these certifications are difficult to obtain and/or expensive for manufacturers, so many companies choose not to get their products tested by one of these three organizations. 
• Sometimes products tested by these three companies are more expensive to try to offset the cost they pay for certification.
• Just because a supplement is not tested by one of these three companies, it does not mean it’s a bad product. We recommend doing some research on the reputability of the manufacturer and calling up the manufacturer and their testing lab to determine their protocols and decide if you feel comfortable consuming the supplement.

Most protein powders naturally contain heavy metals in trace amounts, and consumers have expressed concern about heavy metal contamination when using these supplements. However, a recent study shows that consuming one to three servings of protein powder per day is unlikely to cause adverse health effects.

Heavy metal contamination is only a concern if the amount ingested is over a certain limit. It’s helpful to note that many foods in our diet naturally contain heavy metals that we consume every day at safe levels. A casein protein that has been third-party tested helps ensure heavy metals do not exceed the FDA-established levels for contamination.

Form

You might have noticed that four of the five recommended products on this list are made with “micellar” casein. This means that the milk used to make it has been microfiltered, which leads to a better-tasting product with a more pleasant consistency. Most casein protein powders are made with micellar casein because of this, so you get a more palatable product for protein shakes, smoothies, and more.

Ingredients and Potential Interactions

It is essential to carefully read the ingredient list and nutrition facts panel of a supplement to know which ingredients and how much of each ingredient is included relative to the recommended daily value of that ingredient. Please bring the supplement label to a healthcare provider to review the different ingredients contained in the supplement and any potential interactions between these ingredients and other supplements and medications you are taking.

Because casein is a milk product, you should avoid it if you have a milk allergy.

Dosage

The Recommended Dietary Allowance (RDA) for protein for an average adult is 0.8 grams of protein per day per kilogram of body weight or about 46 grams of protein per day for women and 56 grams of protein a day for men. Research shows that Americans, on average, are getting more than enough protein in their diets—women are getting about 69 grams a day, and men are getting 100 grams a day, on average.

Though people meet their protein needs through food alone, individual needs vary based on different factors. Casein protein powder can help supplement your protein intake if you find it difficult to meet your protein requirements through your diet.

How Much Is Too Much?

There is no Tolerable Upper Limit (UL) for protein intake. The risk appears to be very low for consuming excess protein from food. But with such limited data to show any adverse effects of a high-protein diet from food and supplements, it is not recommended to consume more than the recommended range of protein for the average person.