Although many celebrities and influencers promote collagen supplements, some medical experts worry about their safety. Could they increase your risk of breast cancer? Others wonder whether collagen could help with the side effects of breast cancer treatment.

MyBCTeam members have wondered about taking collagen. One member shared, “I’m four weeks postmastectomy with TRAM flap reconstruction, and I was thinking of starting collagen to speed up recovery.” Other members expressed concerns about collagen’s safety. One asked, “Are collagen supplements safe to take if you have estrogen-positive breast cancer?”

Although there aren’t specific studies about the use of collagen supplements in people with breast cancer, scientists have studied how collagen interacts with breast cancer. This article will get you up to speed on collagen, the role of supplements, and what research shows.

What Is Collagen?

Collagen is the most common protein in your body — it makes up about 30 percent of the total. It provides structure and strength to your skin, muscles, bones, connective tissues, and organs. Because collagen is found naturally in the body as well as in food we eat, it’s generally considered safe for most healthy people.

There are five main types of collagen, often written with Roman numerals (type I, type II, etc.):

• Type 1 — Gives your skin, bones, tendons, and ligaments their structure (most common type of collagen)
• Type 2 — Supports your joints
• Type 3 — Found in your muscles, blood vessels, and organs
• Type 4 — Supports your skin
• Type 5 — Found in your eyes, skin, and hair

As you get older, your body makes less collagen, and the collagen already there breaks down more quickly. As you age and your collagen levels decrease, you may notice:

• Wrinkles or sagging skin
• Muscle loss or muscle aches
• Joint pain or stiff joints

What Is Collagen Used For?

Collagen is used for cosmetic and medicinal purposes. It’s found in wound dressings, blood vessel prosthetics, and dermal fillers (for smoothing lines and wrinkles). Collagen is also sold as a supplement you can take in the form of a tablet, capsule, or powder. It’s been promoted for many uses, including:

• Reversing wrinkles and signs of aging
• Improving skin elasticity (your skin’s ability to stretch and bounce back)
• Improving joint pain and bone defects
• Healing wounds
• Increasing muscle mass
• Improving wound healing
• Stabilizing dental implants and crowns

There are few clinical trials on collagen, though some industry-funded studies suggest benefits for skin and joint health. Collagen may help with skin elasticity, joint mobility, and joint pain. But since most of these studies are funded by the supplement industry, the results could be biased or less trustworthy.

Collagen Supplements for Breast Cancer Treatment Side Effects

Some breast cancer therapies, such as chemotherapy, radiation, and hormone therapy, can cause unpleasant side effects that some people treat with collagen supplements. A MyBCTeam member shared, “I’m taking letrozole. My wrinkles are getting worse and worse, and I’ve got them everywhere! Even on my arms, legs, and stomach.”

Other possible side effects of breast cancer treatment include:

• Joint pain
• Weakened bones
• Dental problems
• Wound healing after surgery
• Nail and skin problems

Some MyBCTeam members have reported noticing that some of these symptoms are relieved when they take collagen. One member said, “I really endorse collagen tablets. The first time I took them, my daughter asked if I had a facial. Wrinkles disappear on the forehead and elsewhere on the face.” Another member shared, “Collagen did help me with stiffness from my arthritis.”

The Connection Between Collagen and Breast Cancer

There haven’t been any clinical trials specifically studying the effect of taking a collagen supplement in people with breast cancer. However, cancer researchers have been studying how collagen in your body interacts with cancer.

The amount of collagen in your breasts can influence your risk of breast cancer and the prognosis (likely outcome). Having dense breasts, which are made up of fibrous tissue including collagen, is a risk factor for breast cancer.

Can Collagen Cause Cancer?

There aren’t any studies linking collagen supplements to cancer. When you take collagen, your body breaks it down during digestion into smaller pieces. These smaller pieces are called peptides, and there’s no proof that they cause cancer. However, cancer cells are known to influence the way collagen is formed. Researchers have found an association between increased collagen expression and a worse breast cancer outlook. Most breast cancer deaths happen when the cancer comes back after a period of remission, called a recurrence. Studies from the journal Breast Cancer Research have found that type 1 collagen is associated with breast cancer recurrence. However, the limited research available has focused on collagen already in the body, as opposed to collagen supplements.

Collagen and Estrogen-Positive Breast Cancer

There may be a higher level of risk associated with collagen supplements for people with estrogen-positive (ER-positive) breast cancer. ER-positive breast cancer is a type of cancer with increased estrogen receptors on the surface of breast cancer cells. These hormone receptors “catch” estrogen in the body and use it to help the cancer grow. Studies have shown that people with estrogen-positive breast cancer who have high levels of type 1 collagen may face a shorter life expectancy.

A study involving mice found that type 1 collagen may change hormonal signals to drive the tumor growth of ER-positive breast cancer and increase the risk of cancer spreading to other organs. This spread is called metastasis. However, this study was done in animals, not humans, and it didn’t test collagen supplements, so we don’t know if the same effects would happen in people. Check with your oncologist before taking any supplements (including collagen) if you’re undergoing treatment for ER-positive breast cancer.

Do Collagen Supplements Increase Breast Cancer Risk?

So far, no studies have shown that taking collagen supplements raises your risk of breast cancer. Collagen from supplements is broken down during digestion, so it doesn’t act like the collagen that’s already in your breast tissue. Cancer research has found that collagen in the body plays a role in how cancer cells grow and spread to other organs. However, researchers haven’t studied how taking a collagen supplement might affect breast cancer. Until more research is done, we don’t know how collagen supplements might affect breast cancer.

As with all supplements in the United States, taking collagen supplements can be risky because you can’t be sure you’re getting exactly what’s on the label. The U.S. Food and Drug Administration (FDA) doesn’t evaluate supplements for safety or efficacy. Supplements may have significantly more or less of the active ingredient on the label. They may also be contaminated with harmful substances such as heavy metals.

Talk to your healthcare team before you take any supplement, including collagen. Dietary supplements may have harmful side effects or interact with your cancer treatment. Your doctor and oncologist should be aware of any supplements, vitamins, and minerals you take. Your doctor or a registered dietitian may be able to recommend ways to boost collagen through improved nutrition, such as eating a balanced diet with foods that contain or promote collagen.

Find Your Team

On MyBCTeam, people talk about their experiences with breast cancer, get advice, and find support from others who understand.

Have you taken collagen supplements for breast cancer side effects? Share your story in the comments below.