The Use of Whey Protein in Cancer Treatment

Whey proteins have long been used as a protein source in sports nutrition and clinical nutrition. However, in recent years, various claims have emerged suggesting a possible link between whey protein consumption and cancer. Much of this debate is based on a superficial interpretation of the relationship between protein intake and cellular growth mechanisms. Such a relationship, however, can only be addressed in light of systematically evaluated scientific data.

This article is based on a peer-reviewed systematic review published in the International Journal of Molecular Sciences in 2025, which examined the anti-cancer potential of whey proteins. The study was conducted according to PRISMA 2020 criteria; in vitro studies, animal experiments, and a limited number of clinical trials published between 2000 and 2024 were searched in PubMed, Scopus, and Web of Science databases. As a result, 24 studies examining how whey proteins might exert effects at the cellular and molecular level in different cancer types were analyzed in detail.

This systematic review was prepared as a result of an international and interdisciplinary collaboration between Constantin Brâncuși University of Târgu Jiu in Romania and academics from the Department of Food Engineering, Faculty of Agriculture, Uludağ University, and the Faculty of Medicine, Balıkesir University, both from Turkey. This study, to which Turkish scientists contributed, deserves particular praise for its high methodological standards in addressing the effects of whey proteins on cancer biology.

WHAT IS WHEY PROTEIN?

Whey protein is a type of protein that makes up approximately 20% of milk proteins and is released during cheese production. Besides being rich in essential amino acids, what distinguishes whey protein from a traditional protein source is its content of bioactive proteins and peptides . Among these components , β-lactoglobulin, α-lactalbumin, and lactoferrin stand out.

The review examined whey proteins in three main forms: concentrate (WPC) , isolate (WPI) , and hydrolysate (WPH) . These forms differ in protein purity, digestibility, and peptide content, which can lead to variations in their biological effects. Hydrolyzed forms, in particular, may exhibit more pronounced biological activity at the cellular level due to their shorter-chain peptides.

One of the main reasons whey proteins are considered functional is their key role in intracellular antioxidant defense thanks to their high cysteine (a type of amino acid) content . This feature transforms whey proteins from a nutrient solely associated with muscle protein synthesis into a biologically active component that can influence oxidative stress, immune response, and cellular balance.

WHICH TYPES OF CANCER HAVE BEEN STUDIED IN WHICH THE EFFECTS OF WHEY PROTEIN?

The systematic review examined the effects of whey proteins on cancer cells in different malignancies (cancerous tumors). However, the strength of the evidence varies depending on the type of cancer and the experimental model used. The majority of studies focused on specific cancer types, with the strongest data obtained in colorectal and breast cancer.

COLORECTAL CANCER

Colorectal cancer is the type of cancer in which the anticancer potential of whey proteins has been most extensively studied . Both in vitro (laboratory studies) and animal studies included in this review have shown that whey protein and its derivatives suppress tumor growth, reduce cell proliferation (cell division), and increase apoptosis (cell self-destruction). In some animal models, a reduction in tumor volume and a delay in tumor formation have been reported.

At the molecular level, whey proteins have been reported to suppress signaling pathways closely associated with colorectal cancer, such as Wnt/β-catenin and PI3K/Akt . A decrease in oxidative stress markers has also been observed.

According to a clinical study conducted in 2019, whey protein supplementation improved nutritional status and reduced treatment-related toxicities, particularly in patients undergoing chemotherapy. These findings suggest that whey proteins may have a supportive, rather than a directly therapeutic, and biologically significant role in colorectal cancer.

BREAST CANCER

Breast cancer is the second most frequently studied type of cancer in terms of the anticancer effects of whey proteins. In vitro (laboratory) studies have shown that bioactive peptides derived from whey proteins reduce proliferation (cell division), halt the cell cycle, and induce apoptosis (cell self-destruction) in breast cancer cells. Lactoferrin and α-lactalbumin derivatives have been reported to be particularly prominent in these effects.

Some studies suggest that whey proteins may increase cellular sensitivity to certain chemotherapeutic agents by suppressing cellular growth via the mTOR pathway .

Furthermore, animal models have shown that whey proteins can positively influence not only tumor growth but also behavioral and metabolic changes caused by cancer.

However, it is particularly emphasized that the data in this area are largely at the preclinical level and limited for clinical generalization.

OTHER TYPES OF CANCER

The review also includes studies examining the effects of whey proteins in various malignancies such as liver cancer, prostate cancer, multiple myeloma, and lung cancer. These studies have reported that whey proteins reduce oxidative stress, increase apoptotic signaling, and in some cases enhance the effectiveness of chemotherapeutic drugs. Therefore, their use in oncological treatments is supported.

Much of the current data for these cancer types is based on cell cultures and animal models. Researchers specifically note that while these findings are biologically significant, they need to be evaluated early in terms of clinical applications. Therefore, more controlled studies are needed to draw clear clinical conclusions regarding the use of whey proteins in these cancer types. However, these findings are promising in terms of the potential of whey protein to aid in cancer treatment.

WHAT DO ALL THESE FINDINGS MEAN?

One of the key points of this systematic review is that although the majority of findings regarding whey proteins come from preclinical (cell culture and animal model) studies, a limited number of clinical trial data are available. The common thread in these clinical trials is that they treat whey proteins not as a "cancer-treating agent," but as a supportive nutritional intervention targeting common problems in cancer patients such as malnutrition, muscle wasting, and treatment toxicities .

Key clinical outcomes highlighted in the review indicate that whey protein supplementation is particularly beneficial in patients undergoing chemotherapy:

• He was able to improve his nutritional status ,

• It can support antioxidant defenses by increasing glutathione (GSH) levels.

• It can reduce cell proliferation (multiplication) ,

• It can increase apoptotic signals ,

• It can improve treatment tolerance by reducing some side effects and complications,

  
  

This shows that it can indirectly contribute to improving quality of life and slowing cancer progression .

The clinical significance of these findings is that success in cancer treatment is not limited to targeting the tumor; patient tolerance to treatment, prevention of weight and muscle loss, preservation of immune function, and toxicity management can also directly influence outcomes. The potential clinical value of whey proteins lies precisely in this area of “supportive oncology.”

However, researchers clearly emphasize the limitations of clinical evidence. The number of existing clinical trials is small; sample sizes are limited, follow-up periods are relatively short, and there are significant differences between the whey products used (concentrate/isolate/hydrolysate). Therefore, the review concludes that whey proteins may be a generally well-tolerated and potentially supportive option for cancer patients; however, presenting them as a "proven anticancer treatment" is not scientifically accurate.

In this context, the most accurate statement is this: Whey proteins are not agents that directly eliminate tumors in cancer; rather, they are an "adjunct/supportive" approach that can contribute to the treatment process by supporting metabolic resilience, redox balance, and nutritional status .

Reference:

• Elmas S, Fındık M, Kıyak R, Taşkın G, Cîrțînă D, Dîrnu R, Guță N, Mecu RM, Bîcă MD. Anticancer Potential of Whey Proteins-A Systematic Review of Bioactivity and Functional Mechanisms. Int J Mol Sci. 2025 Oct 26;26(21):10406. doi: 10.3390/ijms262110406. PMID: 41226446; PMCID: PMC12611071.