Low-Carb, Plant-Rich Diet ‘Appears to be Beneficial For Women With Breast Cancer’

Maintaining a low-carbohydrate diet comprised of mostly plants led to better overall survival for women with breast cancer, according to the findings of a recent study. However, these diets are not associated with better overall breast cancer-specific survival. Studies have determined that there is no correlation between plant-rich low-carb diets and breast cancer-specific survival, but maintaining this type of diet does help with overall longevity.

In a study published in March in the journal Cancer, the diet scores of 9621 eligible women with stage 1, 2 and 3 breast cancer were analyzed. Specifically, three types of diets were calculated based on diet scores: overall low-carbohydrate, animal-rich low-carbohydrate and plant-rich low-carbohydrate. These scores were calculated through food frequency questionnaires following breast cancer diagnosis. The authors confirmed that the risk of overall mortality was lower for women with breast cancer who complied with a plant-rich, low-carbohydrate diet following their diagnosis.

“Choosing plant-based foods like vegetables, whole grains and nuts, which provide protein and healthy fats, while reducing intake of carbohydrates from sugary drinks, added sugar and potentially refined grains, appears to be beneficial for women with breast cancer,” said Dr. Maryam Farvid, an author of the study and founder of Data Statistics Group in Mission Viejo, California, in an interview with CURE. “Additionally, incorporating some animal protein sources like fish, poultry or dairy while replacing carbohydrates may also be advantageous for these women.”

The authors also noted that not every protein is beneficial. Eggs are considered a harmful protein because of its high level in cholesterol, which is linked to a higher risk of breast cancer-specific mortality.

Participants were followed for approximately 12.4 years, with their diets scored according to the amount of carbohydrates they consumed. Survivors who consumed more carbohydrates were on the lower side of the scale, whereas those who ate fewer carbohydrates were on the higher side of the scale. Those who scored higher on the overall low-carbohydrate diet consumed more total protein and total fat, and also consumed less fiber, fruit, whole grains, refined grains, fruit juice, sugar-sweetened beverages and added sugar following their diagnoses. On average, women who scored higher on the overall low-carbohydrate diet had about 37% of their energy come from carbohydrates, 20% from total protein, and 38% from total fat. In contrast, women who scored lower had an average energy intake of about 57% from carbohydrates, 15% from total protein and 24% from total fat.

The study also stated that replacing 3 to 5% of carbohydrate intake with a protein-based source would be beneficial. “When replacing the energy intake from carbohydrates with an equivalent percentage energy intake in a 2000 kcal diet, it would entail exchanging roughly 25 grams of carbohydrates for either 25 grams of protein or 11 grams of fat. In terms of specific examples, a typical sugar-sweetened beverage of 240 ml (8 fluid ounces) generally contains around 25 grams of carbohydrates, while a 1-ounce (28 grams) serving of almonds provides approximately 14 grams of fat and 6 grams of protein,” said Farvid.

Through substitution analyses, the study’s authors stated that replacing 5% of carbohydrates with total protein led to a 13% lower risk of breast cancer-specific mortality and an 8% lower risk of all-cause mortality. Similarly, switching 5% of carbohydrates with animal proteinles to 16% lower risk of breast cancer-specific mortality and a 13% lower risk of all-cause mortality. On the other hand, replacing 5% of carbohydrates with a plant protein leads to an 18% lower risk of all-cause mortality; this result is not associated with lower risks of breast cancer-specific mortality.

Although this study focused on maintaining a low-carbohydrate diet for survivors of breast cancer, Farvid emphasized that survivors should not quit eating carbohydrates completely.

“Carbohydrates play a crucial role in providing energy for our bodies and supporting various metabolic processes. It is never recommended to consume very low amounts of carbohydrates or completely eliminate them from our diet,” she said. “Carbohydrates are the primary source of energy for our brain and muscles, and they also contribute to the overall functioning of our body. It's important to note that the type and digestibility of carbohydrates we consume make a difference.”

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