Janice Stuff, RD, Cancer Prevention Interview

Tuesday, March 27, 2007 - 8:53am

Can you start us with a description of your background?

I am a registered dietitian but presently I am doing nutrition research. And, for several years I did nutrition research regarding the nutritional requirements for infants and children. Recently, I have expanded my research into cancer prevention, and the diets that help prevent cancer in both children and young adults.

Where are you doing that work?

I work at Baylor College of Medicine. My collaboration on cancer prevention is also with an institution here in Houston, the University of Texas M. D. Anderson Cancer Center.

Let's start to talk about some of the things that people need to do to reduce their chances of getting cancer. Do you have a general overview of the first few things that people need to think about?

Yes, I pretty much go along with the wonderful recommendations that are well thought-out by the American Institute of Cancer Research. They have a really good format to inform people. They try to translate the most recent research into real readable and usable information. They offer six main guidelines that help prevent cancer. They would start with choosing a diet based on a plant-based food. The second one is to eat plenty of vegetables and fruits; the third one is maintain a healthy weight. There are so many studies that show as people become overweight and obese, that really increases their risk of cancer. Fourthly, to drink alcohol in moderation, and the next one is eating foods that are low in salt, and finally it's important to prepare and store food safely.

This last guideline is about avoiding food that's gone bad?

Right. I was just thinking of that recent story of the peanut-butter scare. Of course, that wasn't a consumer issue, but it brings to light how food can get contaminated, and you need to be careful in its preparation.

Yes, indeed. That sounds like a good set of recommendations. So, I have heard that refined and processed foods are things that you should minimize as well.

Yes, integrated in the first list I reviewed for you is the importance of a high fiber diet rather then having a piece of white bread or cereal that's over-processed. If you move more towards a high fiber cereals and high fiber breads, which contain some phytonutrients, it helps to prevent colon cancer and various other cancers.

Right. What is it that makes refined foods less healthy?

It's what's been taken away in the processing. The fiber gives foods more structure, and more substance. Also, as this fiber is going through our stomach and gastrointestinal track, it can bind up some bad chemicals, some bad carcinogens. And, so it helps pull them out of our system before they can sit around and do any damage.

So, sometimes you see on these labels, particularly with bread, you see the phrase "enriched." I have come personally to think about that as meaning that they added nutrients that your body can't absorb and took out the good ones.

Yes, maybe that's the case. We have in the nutrition community confusion in the way people label their food, and the government is always in the dilemma of how to get people to label the foods they sell in ways that are not misleading.

Okay, so when you see bread that's labeled "enriched," that's not necessarily something that means it's good.

Yes, you may be right; it maybe enriched with maybe some vitamins, and other things of that nature, which isn't bad. But, as far as the fiber content is concerned, you need to look at the nutrition label to see what types of fiber it is, for example, a wholegrain bread or a whole wheat bread.

Do you have a recommendation for the number of grams of fiber people should try to get in a daily diet?

It's between thirty grams and thirty-eight grams for men; and for women, twenty-one to twenty-five.

And, are there any suggestions that you can make about the mix, for example, is fifteen grams from the same source everyday okay?

Probably it is. So, if some people like to obtain it from whole grain breads, some from brown rice, some from legumes, and some from whole beans that's fine. And, then some people will put a teaspoon wheat germ in their yogurt or breakfast cereal. But, I think if you can obtain all of your grams of fiber from one or two foods, that's fine. But, from a variety standpoint, it's probably better to distribute it over the foods I've just named.

You mentioned drinking alcohol in moderation. Is that suggesting that maybe a glass or two of wine is better then none?

Well, in some of our studies it does prove beneficial particularly in some of the cardiovascular aspects. So, in very low moderation, a glass every other day for some individuals can be beneficial.

What about low-fat diets? Are those helpful?

Yes, they are very helpful in the topic of cancer prevention. For some reason, higher-calorie, higher-fat diets create a metabolism that can encourage precursor or cancer cells to grow and convert into developing cancer. From the animal side, some tests showed that animals that were restricted or under-nourish from the standpoint of calories developed a lot fewer cancers. Then from the epidemiology literature, when we look at it from a human population standpoint, individuals with higher calorie and higher fat intakes have more chances of getting cancers and tumors.

Related to that is having the essential fatty acids, such as the Omega 3's. And, I guess most people maybe have a tendency to get more Omega 6 than Omega 3, and it really should be other way around. Can you talk about that a little bit?

Yes, I know, essential fatty acids are very important in the overall development of chronic disease and heart disease. And, there is some preliminary research on their role in helping prevent cancers. I can't really break it out for you on Omega 6 versus Omega 3. On that I just have to refer the audience to the American Institute of Cancer Research website.

Now there are micronutrients as well; nutrients that don't appear in the standard list of vitamins. But, they are things that you end up getting from fruits and vegetables. Any comments on the role they play or any particular micronutrients you can call out?

It really brings home the point that the whole food can carry hundreds of constituents, and that you can't just rely on supplements. Some micronutrients we are already aware of, and have named them and followed their metabolism; and there are many of them we're unaware of. An example is in the broccoli family of Brussels sprouts, broccoli, and kale. In these types of vegetables there is a phytonutrient called isiothio-cyanate. And, they help the pathways of metabolism where your body maybe exposed to a carcinogen. Isiothio-cyanate has been show to speed up the enzymes and the paths to destroy carcinogens, and that's just one example. There are a number of flavonoids, and there are a number of things in green tea--antioxidants that are beneficial in preventing carcinogens from getting into our bodies and from having a destructive effect.

So, in the case of antioxidants, and you are talking about something that will breakdown the free radicals that your body generates--free radicals being things that are bad for your health.

Right. Antioxidants can prevent free radicals from being formed, or if they are formed they can pull them out.

Right. But, also its true (isn't it?) that if you overdo it, and you take a huge amount of one particular antioxidant into your body, that the antioxidant can become the free radical or the oxidant?

I think you are correct. If you want to destroy a cancer cell, and if it's there, it can be destroyed by radicals. And sometimes the free radical can also attack healthy cells. They think the effects of taking too many supplements is maybe you are allowing the cancer cells not to be attacked by the free radicals, and cut off of their lifecycle.

Interesting. Now, you mentioned flavonoids a little bit earlier. What typically is the source of those?

Okay, flavonoids can be in green tea. Another source of flavonoids can be in some of the fruits and vegetables, fruits being the main source.

Now is there something that you said for berries verses apples, and pears, and oranges, isn't there?

Yeah, berries are given a lot of interesting support because of the phytochemicals they supply; for example, blueberries, blackberries, and strawberries. But, yes, they are sources of antioxidants and flavonoid compounds that seem to help prevent skin, bladder, and lung cancer.

These berries are cancer preventives. What the scientists and the chemists have to do is find the active compounds, and name them, and sometimes that's a little tedious.

You don't even know all the beneficial small things, but the bottom line is in berries, the blue-colored ones are very beneficial.

Blackberries too, right? Or for that matter grapes, as some kinds of grapes seem to have a good benefit.

Yeah, I think one of the compounds in grapes they know of is Reservatol.

Mostly, from red and purple grapes. And as far as we know, it's a phytochemical that slows the growth of cancer cells.

This created the great French Paradox; there is this notion that that the French have such a fatty diet, but they still have a fairly good life span. The argument has been made that it was because of the benefits of Reservatol, which they get from their wine consumption.

Yeah, I believe this compound carries forward into most of the wines, particularly red wine.

What are carotenoids?

Well, it's easy to think of these as being mostly in the yellow and green fruits and vegetables, particularly vegetables. And, the main mechanism we understand from this group of compounds is their antioxidant characteristic. We'd discussed earlier about the role of antioxidants, and this is their role. The body takes these carotenoids, and they have to be absorbed and then broken down. Once this happens, they are active and ready to do their job.

Right. So, you reminded me of an old saying, the notion of eating a rainbow. You want your green foods, of course, but you also want red, and orange, and blue, and purple, and a wide range of colors in your regular diet.

Yeah, I think this concept is a few years old; of course I have been in nutrition several years. And we didn't have an appreciation for the blues and purples. Earlier on we were focused on the yellows, the greens, and the oranges. But, now the newer research brings in the purple and blue colors that are in the grapes, and the berries we were just talking about.

So what do orange-colored foods bring to the picture?

That's the color of the carotenoids. The oranges have some carotenoid activity, but they also have vitamin C. And, vitamin C can play well in antioxidant activity.

For the readers who have discovered that they do have cancer, and are being treated, are there any differences that you suggest in the recommendations for their diet?

Janice Stuff: Not really, it's very important even after you have been diagnosed with cancer to be healthy during your treatment. And, to prevent any recurrence, it's the same thing. These healthier lifestyles, and healthier dietary patterns can greatly increase your probability of not having a cancer recurrence. So, it's never too late even after a diagnosis of cancer. Of course some cancer survivors are tempted to try some very radical supplements. But, I don't recommend these. Just sticking with this healthy life pattern outline by the American Institute of Cancer Research is appropriate for cancer survivors.

We talked a little bit about some of those things that would potentially destroy cancer cells. And it seem to focus very much on plant-based diets, or vegetables and fruits of various kinds that would bring you some of these micronutrients, antioxidants, flavonoids, and carotenoids; not to mention the essential fatty acids as part of the picture. Is that a fair summary?

Yes. That pretty much summarizes it. We didn't have a lot of time to talk about maintaining a healthy weight, and being physical active. But, in addition to your healthy plant-based diet, remember to do some exercise, and step on the scales frequently to make sure your body weight is in the right body range for your height, age, and weight.

Right. That by itself has been shown to have a positive correlaton with lower cancer risk.

Yes, that's true.

Great. And, one thing I think we didn't mention in all of this is consumption of meat products versus a higher level of fruits and vegetables, or for that matter, fish products.

Yeah, we sort of over emphasized the diet of plant based foods. But, what that basically is saying is, that unlike the American who has a diet plan with a high intake of red meat, you need to flip that. And so, on your plate you see a small serving of meat, but its portion controlled and a larger part of the plate is covered with fruits and vegetables. The fatty acids we talked about earlier; their best source is fish. Fish is a very healthy food that we need to think about eating once or twice a week.

Okay, excellent. Well, I really appreciate your time today.