Cruciferous vegetables are worth their weight in gold in the fight against breast cancer. This was emphasized at a recent American Association for Cancer Research’s annual meeting where new evidence highlighted the importance of cruciferous vegetables for breast cancer protection.
The cruciferous family is unique among vegetables because of their glucosinolate content. Glucosinolates give cruciferous vegetables their characteristic spicy or bitter tastes; when the plant cell walls are broken by blending, chopping, or chewing, an enzyme called myrosinase converts glucosinolates to isothiocyanates (ITCs) – compounds with potent anti-cancer effects, including:1
Eating cruciferous vegetables produces measurable isothiocyanates in breast tissue2, and observational studies show that women who eat more cruciferous vegetables are less likely to be diagnosed with breast cancer. In a Chinese study, women who regularly ate one serving per day of cruciferous vegetables had a 50 percent reduced risk of breast cancer.3 A 17 percent decrease in breast cancer risk was found in a European study for consuming cruciferous vegetables at least once a week.4
We know that childhood and adolescence are the most crucial times for environmental stimuli to affect breast cancer risk, but changes made during adulthood and even after diagnosis still have the potential to create positive changes in the body.
A study kept track of cruciferous vegetable intake in Chinese women with breast cancer for the first three years after diagnosis, and followed the women for a total of five years. They found dose-response effects; this means that the more cruciferous vegetables women ate, the less likely they were to experience breast cancer recurrence or die from breast cancer. When the women were grouped into four quartiles of cruciferous vegetable consumption, the highest quartile had a 62 percent decrease in risk of death and a 35 percent reduced risk of recurrence compared to the lowest quartile.5
This data supports a previous report from the Women’s Healthy Eating and Living (WHEL) study. Breast cancer survivors who reported higher than median cruciferous vegetable intake and were in the top third of total vegetable intake had a 52 percent reduced risk of recurrence – especially powerful since the average intakes were quite low – 3.1 and 0.5 servings/day of total and cruciferous vegetables, respectively.6
Don’t forget: cruciferous vegetables must be chopped, crushed, or chewed well for maximum benefit.
The myrosinase enzyme is physically separated from the glucosinolates in the intact vegetables, but when the plant cells are broken, the chemical reaction can occur and ITCs can be formed. The more you chop before cooking (or chew if you are eating the vegetables raw), the better. Some ITC benefit may be lost with boiling or steaming, so we get the maximum benefit from eating cruciferous vegetables raw.
However, gut bacteria also have the myrosinase enzyme, so additional ITC production may occur in cooked cruciferous vegetables after we eat them. Also, we can increase ITC production from cooked cruciferous vegetables by having some shredded raw cruciferous vegetables such as cabbage, kale, collards or arugula in a salad in the same meal to supply the myrosinase enzyme, which the body can use during the digestive process.