Dietary Flavonoid Patterns and Prostate Cancer: Evidence from a Mexican Population-Based Case-Control Study

[Graham49]

Interesting although slightly controversial study. I don't think there are many studies comparing the efficacy of different flavonoids. My summary is given below.

British Journal of Nutrition , Accepted manuscript , pp. 1 - 30

DOI: doi.org/10.1017/S0007114521...

This population-based case-control study was carried out in Mexico City and used food-frequency questionnaires over 3 years. A database was used to estimate the daily intake (mg/d) of flavanoids for 395 confirmed incident PC cases and 797 population controls matched by age (±5 years). Three flavanoid dietary intake patterns were determined through principal component analysis, and their association with PC was estimated using logistic regression models. Three flavanoids patterns were identified as:

1. The Gallate pattern (GP) characterized by (-)-epicatechin-3-O-gallate, (-)-epigallocatechin-3-O-gallate and (+)-gallocatechin;

2. The Luteolin pattern (LP) characterized by luteolin and (-)-epigallocatechin-3-O-gallate;

3. The mixed pattern (MP) that included (+)-catechin, (-) -epicatechin, and quercetin.

Results

A higher GP intake (OR T3 vs.T1=0.47; 95% CI 0.33-0.66) was associated with a decreased PC likelihood.

A higher LP intake (OR T3 vs. T1=0.39; 95% CI 0.27-0.59) was associated with a decreased PC likelihood.

In contrast, a higher MP intake (OR T3 vs. T1=2.32; 95% CI 1.67-3.23) was associated with increased PC likelihood.

They took account of potential confounders such as educational level, history of chronic disease, history of sexually transmitted disease, history of prostate cancer in first-degree relatives, leisure-time physical activity and smoking patterns and consumption of raw tomato, green-yellow leafy vegetables and green-yellow nonleafy vegetables.

I don't know why they took account of raw tomatoes but not cooked tomatoes!

A sensitivity analysis was performed, adjusting each flavonoid intake pattern model with each of the other patterns.

There is no mention of whether any analysis was made of whether particular foods high in the individual flavanoids were generally consumed in conjunction with healthy or unhealthy foods. For example if the MP flavanoid foods were often consumed with high saturated fat, processed meat or high sugar foods. Conversely, perhaps the use of foods high in GP or LP flavonoids might be associated with the use of other more healthy foods.

The study concluded that their findings support the existing evidence of the anticarcinogenic capacity of some flavonoids, particularly (-)-epigallocatechin-3-O-gallate and luteolin. However, well-designed clinical trials are needed to further demonstrate their beneficial effects.

[Schwah]

For the rest of us dummies, what does this study imply we should and should not eat please ?

Schwah

[Graham49 in reply to Schwah]

Taking their results at face value a possible interpretation would be:

Increasing intake of LP (Luteolin) rich foods such as celery, parsley, broccoli, onion leaves, carrots, peppers, cabbages, apple skins etc reduce prostate cancer.

Increasing the intake of GP (Gallate) rich foods such as green tea, oolong tea, black tea, camomile tea, various nuts, etc reduce prostate cancer.

Increasing intake of Catechin and Epicatechin rich foods such as cacao beans, blackberries, dark chocolate, red wine, black plums, black grapes, black grapes, various nuts etc increase prostate cancer.

Increasing intake of quercetin rich foods such as onions, kale, tomatoes, broccoli, blueberries and apples etc increase prostate cancer.

Things that are not discussed in the paper such as some foods such as various nuts, broad beans and blueberries are in both the good and bad food categories. Also there are various studies (generally in vitro or animal) indicating the anti PCa properties of many of the foods on the bad side.

IMO the study has not taken full account of the association of good foods and bad foods. To give a hypothetical extreme case: a meal of burger, chips,

onions, tomato sauce and a glass of red wine and a chocolate milkshake might be high in MP flavanoids but I doubt it would be good for prostate cancer, and you would not expect to help PCa by having more of this food.

The main positive thing I get out of this study is with regard to Luteolin rich foods. I don't think I consume enough. I will try to increase consumption and probably take a Luteolin supplement. Patrick has posted a number of positive studies for Luteolin.

[GeorgeGlass in reply to Graham49]

Many of these sound contradictory, like: onions and onion leaves and nuts vs nuts, blueberries, tomatoes etc. What are your thoughts one year since this post?