Great questions. We don't know the answers.
Actually, we have a really good idea of the answer.
I was trying to get you to go and actually read the study because most all the questions I asked are answered in the study (which is available online for free).
So, let me do it for you.
1) Is anyone here not recommending you to include cruciferous veggies as part of your diet?
No. If anyone is following the basic guidelines and principles of the program, they are eating vegetables, including cruciferous veggies every day, if not at most meals. I am at the 10-day program right now and not only are there 2 large chafing dishes of veggies at lunch and dinner, veggies are mixed into most entrees and most soups and there is a also a salad bar at both meals too. Raw veggies, including cruciferous ones are available throughout the day, as snacks too.
2) Do you think that means you should only eat cruciferous veggies?
Of course not. We know that a variety of veggies are good.
3) Do you know what the population was that they did the study on, and what was the diet they were eating?
This was done on the Mens Health Professionals data set, which, we know from several other studies, were not eating a very healthy diet at all.
4) Did you look to see what a serving was and how many servings it took to have that benefit?
A serving is about 1/2 cup cooked and for broccoli, those who were eating the least amount were eating less than 1 serving per week. Those who were eating the high amount of were eating about 2 (or more) servings per week
For cabbage, those who were eating the least amount were eating less than 1 serving per month. Those who were eating the high amount were eating about 1 (or more) servings per week
So, this huge effect was seen by just eating about 1-2 servings per week but only when compared to those who were eating less than 1 serving per week or per month.
5) How do the answers from all these questions about this study impact someone on a healthy diet and who is already eating cruciferous veggies in their daily diet.
All it showed was that in an unhealthy population, by eating just one to three servings of broccoli and/or cabbage per week, they were able to get the benefit. In addition, typically, in these kinds of studies, the impact of the effects go way down as the diet of the subjects gets healthier (as we see in the nut studies). So, we see the biggest benefits in those who have the most room for improvement.
So, how does comparing two groups who are both consuming an unhealthy diet, who go from almost no servings of cruciferous veggies to consuming 1-2 serving per week compare to people already eating a health diet and consuming cruciferous veggies on a regular basis?
6) The study was done in 1999. Have any other studies confirmed and supported these results, or contradicted them or refuted them?
Yes and no. Some have shown similar benefits and some have shown less benefit and some have shown no benefit in relation to cancer
A study in 2010 showed a similar benefit from raw broccoli intake and the difference was seen in those eating eating 1 or more servings per month vs those eating less than 1 serving per month;
Also, the latest report on Cancer and Nutrition, which reviewed over 7000 studies said that the overall data in relation to bladder cancer was either of too low quality, too inconsistent, or the number of studies too few to allow conclusions to be reached. And that while their earlier report showed that vegetables and fruits probably protect against bladder cancer, the evidence for these foods is now considered to be weaker, and in this case, very much so for this specific cancer.
I guess what I'm curious about is... maybe we should err on the side of caution?
We are in many ways.
First, we are already eating an diet that is way more nutrient dense then the healthiest diet any of the subjects in any of these studies is consuming.
Second, in this latter study, they got the benefit from eating just 1 serving a month. In the former study, they got the benefit from eating just 1-2 servings a week.
Well, those of us who are following the recommended guidelines & principles are eating 1-3 servings (or more), 1-2x a day (or more).
That is a 30-90x increase over the amount in the latter study and a 7-14x increase over the amount in the former study.
And, in addition, we are eating all of this as part of a diet that is already much healthier than the diet the subjects in the study were eating. It is also much lower in calorie density (a benefit to cancer risk reduction) and it is also much higher in overall nutrient density (another potential benefit to cancer risk reduction.)
Third, as I explained in this post (which is making the same point but in regard to carotenoids)...viewtopic.php?f=22&t=6067&p=250825
"'Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids', Food and Nutrition Board. Institute of Medicine. National Academy Press, Washington D.C. Pp. 343-344 (2000)"http://www.nap.edu/openbook.php?record_id=9810&page=353
"These data, although in varying populations, suggest that 3 to 6 mg/day of β-carotene from food sources is prudent to maintain plasma β-carotene concentrations in the range associated with a lower risk of various chronic disease outcomes (see Table 3)."
As just detailed, plasma and tissue concentrations of carotenoids have been associated with a variety of health outcomes; that is, higher concentrations are associated with a lower risk of cancer, coronary heart disease, and all-cause mortality. This could be used as a possible indicator for establishing requirements for carotenoids. However, the limitation of this approach is that it is not clear whether observed health benefits are due to carotenoids per se or to other substances found in carotenoid-rich foods.
Thus, these data are suggestive of prudent intake levels, not required levels of intake. Recommendations have been made by a number of federal agencies and other organizations with regard to fruit and vegetable intake. Nutrient analysis of menus adhering to the U.S. Dietary Guidelines and the National Cancer Institute's Five-a-Day for Better Health Program, for example, indicates that persons following these diets would be consuming approximately 5.2 to 6.0 mg/day provitamin A carotenes on average if a variety of fruits and vegetables were consumed (Lachance, 1997). Similar levels would be obtained by following Canada's Food Guide for Healthy Eating which specifies a minimum of five servings of vegetables and fruit (Health Canada, 1997). Other food-based dietary patterns recommended for the prevention of cancer and other chronic diseases would provide approximately 9 to 18 mg/day of carotenoids (WCRF/AICR, 1997).
NOTE: this is 3-6x the amount recognized as being enough to lower disease risk.
It is also based on the WCRF/AICR report from 1997. In many other discussions here, I have quoted the newest WCRF/AICR report from 2007 saying that they now more than ever, recommend dietary "patterns" over recommending specific "individual foods".
In other words, if Americans would just get in the recommended amounts of fruits and veggies, it would not only provide carotenoids, but more than enough of all of them to produce the beneficial health outcomes, including reduced risks of cancer. And anyone following a Whole Food plant based diet, as recommended here, would already be consuming way more than enough.
So, yes, by following the basic principles and guidelines of the program, we are all doing way better than anyone in any of the studies (and the executive reports are recommending) and are already erring way on the side of caution.
For what you are saying to be true, you would need to show me some evidence that compared people who were already eating a very healthy diet that already including the amount of cruciferous veggies per day I mentioned, to someone eating the exact same healthy diet with a few more servings of cruciferous veggies per day.
Not only is there absolutely no shred of evidence supporting this, we do have some evidence that shows it really doesn't make a difference.
And, as David Katz, MD said, anyone telling you anything different is either "misguided, selling something or both."