Low-Fat Diet Could Help Against Breast Cancer

Henrietta Strickland
May 18, 2019

Severely obese women who opt for weight-loss surgery may be cutting their risk of breast cancer along with their extra pounds, a large USA study suggests. And the chance of premature death from breast cancer fell by 21 per cent.

The research, by the Women's Health Intitative led by Dr Rowan Chlebowksi, from Harbor-UCLA Medical Center, tracked 48,835 postmenopausal women age 50 to 79 with no previous history of breast cancer for an average of 20 years, during which 3,374 cases of breast cancer were diagnosed.

Breast cancer treatments have come a long way in recent decades, but understanding how to prevent tumors from forming in the first place has been a major challenge. Obesity has been linked to 12 different types of cancers, including postmenopausal breast cancer, according to the American Institute for Cancer Research. "It helps us, in general, to say that it is worth coaching our patients to put fruits, vegetables and grains on their plates".

However, trans women's risk for breast cancer associated with hormone therapy was still substantially lower compared with cisgender women in the general population (IR 0.3, 95% CI 0.2-0.4), they wrote in The BMJ.

The study included 2,260 trans women and 1,229 trans men receiving gender affirming hormone treatment at a specialist clinic in Amsterdam between 1972 and 2016.

During the presscast, Chlebowski also mentioned a separate study that will be presented at ASCO, investigating the same dietary modification in women with poor metabolic factors such as diabetes and high blood pressure.

Between 1993 and 1998, the women were randomly assigned to one of two dietary groups.

Half of the participants were asked to follow a typical diet, where fat accounted for around a third of their daily calories. Fat intake in the comparison group stayed about the same.

Chlebowski said the low-fat diet was close in content to the Dietary Approaches to Stopping Hypertension (DASH) diet.

"[The keto diet] shuns many healthy, whole plant foods - beans, legumes, certain fruits and vegetables, whole grains and pseudograins", nutritionist Andy Bellatti previously told INSIDER. The groups were similar in terms of age, medical conditions and body mass index (BMI, a ratio of weight to height). He said the researchers factored the weight difference into their calculations and that weight alone didn't affect the risk of death.

Women in the balanced, low-fat diet group stuck to the diet for roughly 8.5 years. And they did increase their intake of fruits, vegetables, and grains. Low-fat dietary pattern and long-term breast cancer incidence and mortality: The Women's Health Initiative randomized clinical trial.

"We don't know why so many of us get breast cancer", Bailey-Dorton said.

The study authors said the dietary-modification group used a diet similar to one called DASH - for Dietary Approaches to Stop Hypertension - which is created to prevent or treat high blood pressure.

In the meantime, Chlebowski said he thinks the message should be one of dietary moderation rather than looking for any one particular food or food group. Women have been urged to cut down on meat and dairy products or choose lower-fat options after the study found evidence that such changes could lengthen their lives. He gave results Wednesday in a telephone news conference held by the American Society of Clinical Oncology ahead of its annual meeting later this month. Findings presented at meetings are typically viewed as preliminary until they've been published in a peer-reviewed journal. Lidia Schapira, an ASCO breast cancer expert.

She noted, "This was not an incredibly restrictive diet".

This population-which now includes more than 5 million women in the US-is three times more likely to die from breast cancer than women with normal metabolic function.

"They were getting fewer breast cancers, and even when they did get breast cancer, their death rate was reduced", Bertagnolli said.

Other reports by Click Lancashire

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