A new study analyzed the effects of omega-3 fatty acids in fish oil on the growth rate, metastasis, and survival of breast cancer.

Breast cancer is the most common cancer in women worldwide. Many studies have shown the influence of diet on cancer. While no food can completely prevent breast cancer, certain foods can certainly help lower your risk of breast cancer or decrease the rate of breast cancer growth.

Incidence of breast cancer in relation to fat intake

Although the relationship between dietary fat intake and breast cancer is controversial, many epidemiological studies suggest that the association between dietary fat and breast cancer is due to the type of fat intake, rather than total fat intake. Studies have shown that there is a significant difference in the incidence of breast cancer between Western and Asian populations. This difference may be due to a lack of fish consumption in a typical Western diet high in omega-6 polyunsaturated fatty acids (PUFA), which are known to be anti-inflammatory.

A diet high in fish, on the other hand, is rich in omega-3 fatty acids, which are helpful in reducing inflammation. Therefore, the ratio of omega-3 and omega-6 fatty acids in the diet regulates the body’s inflammatory status, which in turn can affect the rate of growth and spread of breast cancer.

Long-chain omega-3 fatty acids are not synthesized by the body

Fish oil supplements contain long-chain omega-3 fatty acids that are not synthesized by the body and must be ingested through food. The role of these omega-3 fatty acids in altering the microenvironment of the breast tumor and in regulating metastasis is an important determinant of the ability of fish oil supplements to lower the rate of breast cancer growth.

The study analyzes the effects of omega-3 and omega-6 PUFA on breast cancer

A study recently published in the journal Clinical & Experimental Metastasis analyzed the effects of long-chain omega-3 fatty acids on breast cancer growth rates and metastasis to various organs such as the bones, heart, kidneys, ovaries, and contralateral mammary glands.

Researchers at the University of Nebraska Medical Center, USA, conducted the study on 40 adult female mice. The mice were divided into two groups and both groups received a liquid diet containing the same number of calories and the same percentage of fat. The only difference in their diet was that one group was fed vegetable oils high in omega-6 polyunsaturated fatty acids, while the diet in the other group contained fish oil high in long chain omega-3 polyunsaturated fatty acids .

After 16 weeks following this diet, 4T1 breast cancer cells were injected into both groups of mice. 4T1 breast cancer cells cause aggressive breast tumors to form that spread to preferred metastases such as the lungs and liver. After injecting breast cancer cells for 35 days, the researchers autopsied the mice in both groups.

Reduced breast cancer growth rate in mice fed omega-3 fatty acids

The researchers observed that mice on the omega-3 diet took much longer to develop breast cancer than mice on the omega-6 diet. Because of the slower breast cancer growth in mice fed omega-3, the size of the tumor was 50% smaller and the spread of cancer cells to both preferred and other organs was compared to mice fed omega-6 much lower.

The researchers observed that the mice fed the omega-3 diet survived longer than the mice fed the omega-6 diet. Notably, two mice in the omega-3 diet group did not develop breast cancer at all.

How do omega-3 fatty acids slow the growth rate of breast cancer?

T cells are an important type of white blood cell that play a huge role in the immune system. They are especially important in cell-mediated immunity, which is the primary defense against cancer.

In this study, the researchers found much higher numbers of T cells in the autopsied tissues of the mice given the omega-3 diet than in the mice given the omega-6 diet. In addition, less inflammation was seen in mice in the omega-3 group. Analysis of tumor tissues showed less new blood vessel formation in the tumor, higher tumor cell death, and increased interleukin 10, an anti-inflammatory cytokine, in mice fed omega-3 compared to mice fed omega-6. These changes suggest that omega-3 fatty acids play an important role in reducing the rate of breast cancer growth.

Does an Omega-3-Rich Diet Prevent Breast Cancer?

This study shows the beneficial effects of consuming long chain omega-3 fatty acids. Eating a diet high in foods high in omega-3 fatty acids, such as fish oil, helps suppress inflammation and promote T-cell immunity to tumors, thereby reducing the development and spread of breast cancer.

However, the researchers warn that eating an omega-3 rich diet can suppress or delay the development of breast cancer, but it may not prevent it completely. Also, since these studies were performed with a strain of mouse and one type of tumor cell, the researchers suggest the need for future studies to validate the generalizability of these results.

Include long-chain omega-3 fatty acids in your diet

This study clearly concludes that diets high in omega-3 polyunsaturated fatty acids decrease breast cancer growth, resulting in decreased incidence and number of metastases, thereby increasing mouse survival.

Although more study is needed to conclude that fish oil lowers breast cancer risk, adding omega-3-rich foods like salmon, mackerel, and anchovy can reduce breast cancer growth rates.

Written by Preeti Paul, MS Biochemistry

Reference: Saraswoti Khadge et al., Long Chain Omega-3 Polyunsaturated Fatty Acids Reduce Breast Tumor Growth, Multi-Organ Metastasis, and Improve Survival. Clinical and experimental metastasis. https://doi.org/10.1007/s10585-018-9941-7


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