Recently a study on the impact of a low-fat diet on breast cancer was published showing that a low-fat diet is associated with a 20% risk reduction of mortality from breast cancer.

In this study they followed 50,000 women, half had changed their diet to low fat (for at least eight years in duration), and half continued with "normal diet". And the low-fat diet was associated with 20% reduction in death from breast cancer (if five women died from breast cancer in "normal food group" then only four would die in the low-fat group). And this reduction is high, in some cases, more than any medication that we recommend women.

This does not mean that you should not take the medication. It implies that diet works together with all the medication that we recommend for the treatment of breast cancer.

But is this reduction in mortality (death form the breast cancer) related to the decrease of fat or change in diet in general?
This study does not answer this. The problem with this study is that it started in the 90s when we, as a society, especially in Western culture, had a phobia of fat. The researchers did not look into a different type of fat reduction, especially regards good and bad fats. This study does not answer whether a reduction in fat caused this reduction in a number of deaths, or whether the increase in vegetables, fruit and grains. But what it does show that sustained healthy diet leads to a lower number of breast cancer deaths.

Multiple other studies have looked into the effect of diet on breast cancer. They did not follow women for 20 years, and on average, they did not modify the diet of women.

Fat and risk of breast cancer
Fat from different types of food is likely to have different effects on breast cancer. Fish and marine fats are associated with a lower risk of breast cancer than nut or mammalian fat. High fat intake is associated with the development of adipose tissue which is associated with the development of oestrogens.

Meat consumption and risk of breast cancer
Hard to show the link or association. And this is because we eat different types of meat, we cook it differently, we consumed it differently. The postmenopausal women who eat red meat have a slightly higher risk of development of breast cancer than pre-menopausal women. The new genetic trials show that intake of well-done meat in women with specific genetic changes are associated with increased risk of breast cancer.

Dietary fibre and breast cancer
Inconclusive research, at most there is a fragile association of high fibre intake and lower breast cancer.
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Alcohol and breast cancer
There is an increase in the risk of breast cancer with alcohol intake, but this increase is linked to the drunk amount. I have written a blog previously on this topic.

Phytoestrogens and breast cancer
Phytoestrogens are plant substances that are similar to oestrogens. Isoflavones, present in soybeans and soy products are similar to human oestrogens. The effect of phytoestrogens on breast tissue can be seen in males who develop gynecomastia (development of breast tissue) when they have a high intake of soy, and it's products. Some studies have shown that consumption of isoflavones can be associated with a lower risk of breast cancer, but only in postmenopausal women and Asian populations. This association is not seen in Western women.

Vitamin D and Breast Cancer
It has been postulated that vitamin D can reduce the risk of breast cancer. This effect is seen only in pre-menopausal women. Also, this reduction depends on the amount of Vitamin D.

Iron and Breast Cancer
High levels of iron are associated with a higher risk of breast cancer.

Folate and Breast Cancer
No obvious evidence for or against.

What does this all mean?
It means that healthy food is associated with a lower risk of breast cancer. We should all strive to eat more raw, unprocessed vegetables, fruit and grains and less processed food, including processed fat, grains and sugars. We should strive to have less red meat and more fish or vegetable protein.
The biggest issue is that healthy food is more expensive than processed food. So poor people will be even more affected. I believe that poverty is the most significant health problem and that we need to look at solving this issue.

Future
We will get to know more about the effect of diet on the development of cancers. Through genetic profiling of individuals, we will be able to tell which foods should be encouraged and which foods discouraged in specific genetic profiles. But this is still decades away.