The benefits of fermented milk products for cancer are controversial: what is the role of kefir, yogurt, cottage cheese and cheese in the treatment and prevention of cancer?

Fermented (fermented milk) products include those in which microorganisms, most often lactic acid bacteria, convert lactose into lactic acid, according to Pannochka, an online publication for girls and women from 14 to 35 years old.. net The most common types are kefir and yogurt, the benefits of which are well known.

Various microorganisms are known that can be used for this process..

Under their influence, products can receive certain properties..

Bioactive peptides and other compounds contained in fermented milk products can have hypotensive, bacteriostatic, immunomodulatory effects.

In addition, fermentation can enrich the dairy product with vitamins such as cyanocobalamin, folate and biotin, as well as unsaturated fatty acids.

The consumption of fermented milk products is considered by some scientists as a potential way of prevention, and even a valuable addition to cancer treatment..

Numerous in vitro and animal model studies suggest fermented dairy products may have anti-cancer properties.

Several epidemiological studies have looked at the link between sour milk intake and cancer, but the results have been mixed.

Human studies have also been conducted to determine if kefir can relieve symptoms and prevent the toxic effects of chemotherapy..

In vitro and animal models.

Many studies have evaluated the potential anticancer properties of kefir, a popular product made with lactic acid symbiont bacteria and yeast.. The latter are a source of vitamins A, K, B1, B2, B5, B12 and C, folate, carotene, as well as a number of essential amino acids and minerals.

The Iranian systematic review led by Rafie and Hamedani included 11 studies published up to 2015. This large-scale work allowed us to evaluate the potential preventive effects of kefir. In the review, all studies confirmed some of the antitumor properties of kefir, primarily antiproliferative effects (inhibition of tumor cell division and tumor growth, both in vitro and in animal models).

Other studies by Iranian scientists Sharifi, Jalali and co-authors have shown that kefir induces cancer cell apoptosis in acute erythroleukemia, myeloid leukemia, colon cancer and breast cancer..

There is evidence that kefir inhibits the proliferation of colon cancer cells, stopping the cell cycle in the G1 phase, and also induces apoptosis of cancer cells through a caspase-dependent pathway..

Fermented milk products and cancer: epidemiological evidence.

In October 2018, the International Journal of Cancer published the results of a meta-analysis of 61 studies with 1.9 million participants. The analysis showed that in cohort studies, consumption of fermented dairy products significantly reduced the risk of developing cancer (odds ratio 0.86; 95% CI 0.80-0.92).

Yogurt was the most likely to reduce cancer risk in cohort studies (odds ratio 0.81; 95% CI 0.74-0.88).

When analyzed by cancer type, fermented milk products significantly reduced the risk of bladder cancer, colorectal cancer, and esophageal tumors..

Another meta-analysis, including 11 cohort studies and over 700,000 participants, found no association between yogurt or cheese consumption and cancer mortality.. Such data was published in 2016 by another authoritative magazine Nutrition Journal..

According to Lu, Chen et al, consumption of fermented foods (predominantly dairy products) was not associated with all-cause mortality or cancer mortality in large cohort studies.. Many epidemiological studies have focused on the link between sour milk consumption and colorectal cancer. Kampman and colleagues reported a weak association between fermented milk consumption and a reduced risk of colon cancer back in 1994, but the results were unreliable..

Since then, a prospective cohort study of Pala and Sieri with 12 years of follow-up has shown that regular yogurt consumption significantly reduced the risk of colon cancer (OR 0.65; 95% CI, 0.48-0.89).

Here, the authors significantly improved the methodology by adjusting for variables such as dietary calories, body weight, smoking, education, animal fat, red meat, and alcohol consumption.. Unfortunately, a meta-analysis found that increased consumption of cheese was not associated with morbidity.

The effect of fermented milk products on other types of cancer is controversial.

A meta-analysis of epidemiological studies published in 2015 in the Journal of breast cancer found that yogurt consumption did not significantly, but reduced the risk of breast cancer (hazard ratio 0.91; 95% CI 0.83-0.99).

Fermented dairy products such as yogurt, cheese, and / or cottage cheese are not associated with endometrial, ovarian, stomach, pancreatic, lung, and liver cancers. As ironic as it may sound, restricting dairy products helps prevent certain types of cancer.. Thus, low consumption of kefir was associated with a decrease in the risk of bladder cancer (OR 0.71; 95% CI 0.56-0.91).

However, cheese may increase the risk of liver cancer in children, as evidenced by the 2014 European cohort study (OR 1.56; 95% CI 1.02-2.38).

Yogurt, kefir and toxic cancer chemotherapy.

There is evidence that kefir can reduce chemotherapy-induced toxicity by alleviating discomfort, nausea, and other side effects of cancer treatment with cytostatics..

However, not all studies have shown positive results..

Topuz and Derin in 2008 compared oral kefir lavage with 0.09% NaCl to prevent mucositis associated with 5-fluorouracil chemotherapy. The authors did not find significant differences in the frequency of mucositis or the content of pro-inflammatory cytokines in mucosal cells..

In another randomized study led by the same authors, kefir consumption increased the number of gastrointestinal symptoms during colorectal cancer treatment.. On the other hand, kefir improved sleep compared to control.

conclusions.

Fermented milk and cancer is a new area of \u200b\u200bscientific interest with many blank spots. Experiments in vitro or on animals suggest anti-cancer properties of sour milk, but epidemiological data are still ambiguous..

More adequate human studies are needed to translate promising laboratory results into clinical practice.

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