Should Women at High Risk for Breast Cancer Avoid Soy?

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Which dietary changes could reduce free radical damage and also improve DNA repair in women with mutated BRCA genes?

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Five studies have been performed on breast cancer survival and soy foods, involving more than 10,000 breast cancer patients. And, those who eat more soy live longer, and have a lower risk of the cancer coming back. But, what about women who carry breast cancer genes? Fewer than 10% of breast cancer cases run in families. But, when they do, it’s most likely mutations to one of the tumor suppressor genes—BRCA1 or BRCA2—that defend the integrity of our genes. They are involved in DNA repair, and so, if either one of them is damaged, or has mutations, chromosomal abnormalities can result, which can set us up for cancer.

This idea that we have tumor suppressor genes goes back to famous research in the 60s that showed that if you fuse together a normal cell with a cancer cell, the cancer cell doesn’t turn the normal cell malignant. Rather, the normal cell suppresses the cancerous one. Tumor suppressor genes are typically split up into two types. There are gatekeeper genes that keep cancer cells in check, and caretaker genes that keep the cell from going cancerous in the first place. And, BRCA genes appear able to do both—that’s why their function is so important.

Until recently, dietary recommendations for those with mutations focused on reducing DNA damage caused by free radicals, by eating lots of antioxidant-packed fruits and vegetables. If your DNA-repair capacity is low, you want to be extra careful about damaging your DNA in the first place. But, what if we could also boost BRCA function?

In my last video on the topic, I showed how, in vitro, soy phytoestrogens could turn back on BRCA protection suppressed by breast cancer, upregulating BRCA expression as much as 1,000% within 48 hours. But, does that translate out of the petri dish and into the person? Apparently so.

Soy intake was only associated with 27% breast cancer risk reduction in people with normal BRCA genes, but a 73% risk reduction in carriers of BRCA gene mutations. So, a healthy diet may be particularly important in those at high genetic risk. Meat consumption, for example, was linked to twice as much risk in those with BRCA mutations—97% increased risk, instead of just 41% increased risk of breast cancer in those with normal BRCA genes.

So, same dietary advice—just more important when there’s more risk.

Please consider volunteering to help out on the site.

Image credit: KOMUnews via flickr. Image has been modified.

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Five studies have been performed on breast cancer survival and soy foods, involving more than 10,000 breast cancer patients. And, those who eat more soy live longer, and have a lower risk of the cancer coming back. But, what about women who carry breast cancer genes? Fewer than 10% of breast cancer cases run in families. But, when they do, it’s most likely mutations to one of the tumor suppressor genes—BRCA1 or BRCA2—that defend the integrity of our genes. They are involved in DNA repair, and so, if either one of them is damaged, or has mutations, chromosomal abnormalities can result, which can set us up for cancer.

This idea that we have tumor suppressor genes goes back to famous research in the 60s that showed that if you fuse together a normal cell with a cancer cell, the cancer cell doesn’t turn the normal cell malignant. Rather, the normal cell suppresses the cancerous one. Tumor suppressor genes are typically split up into two types. There are gatekeeper genes that keep cancer cells in check, and caretaker genes that keep the cell from going cancerous in the first place. And, BRCA genes appear able to do both—that’s why their function is so important.

Until recently, dietary recommendations for those with mutations focused on reducing DNA damage caused by free radicals, by eating lots of antioxidant-packed fruits and vegetables. If your DNA-repair capacity is low, you want to be extra careful about damaging your DNA in the first place. But, what if we could also boost BRCA function?

In my last video on the topic, I showed how, in vitro, soy phytoestrogens could turn back on BRCA protection suppressed by breast cancer, upregulating BRCA expression as much as 1,000% within 48 hours. But, does that translate out of the petri dish and into the person? Apparently so.

Soy intake was only associated with 27% breast cancer risk reduction in people with normal BRCA genes, but a 73% risk reduction in carriers of BRCA gene mutations. So, a healthy diet may be particularly important in those at high genetic risk. Meat consumption, for example, was linked to twice as much risk in those with BRCA mutations—97% increased risk, instead of just 41% increased risk of breast cancer in those with normal BRCA genes.

So, same dietary advice—just more important when there’s more risk.

Please consider volunteering to help out on the site.

Image credit: KOMUnews via flickr. Image has been modified.

Doctor's Note

What about women without breast cancer genes or those who have already been diagnosed? See my video Is Soy Healthy for Breast Cancer Survivors?. The older video I referred to is BRCA Breast Cancer Genes and Soy.

What is in meat that may increase risk? See:

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