Fiber, Plant Food, and Ovarian Cancer

Fiber, Plant Food, and Ovarian Cancer

Review of J Nutr 2003;133(6):1937-42.

A recent study published in the Journal of Nutrition investigated several dietary factors and ovarian cancer risk. This article review discusses the findings of this study. This study indicates that eating more fiber, vegetables, and poultry (chicken) DECREASES risk of ovarian cancer. We provide PRACTICAL information on what these findings mean. We explain which specific foods and nutrients appear to most decrease risk of ovarian cancer. Most importantly, we provide ideas for using this information in a dietary plan to reduce ovarian cancer risk. Factors such as reproductive history, age, and genetics cannot be changed, but diet and nutrition can! This type of information will allow women to take concrete and practical steps to decrease their risk of ovarian cancer.

Note: Numbers appearing at the end of sentences indicate research references. References are listed at the end of each article.

Background

As early as the 1970s, researchers concluded that diet might be linked with hormone related cancers such as breast, prostate, endometrial and ovarian cancers (1-3). This early research focused less on ovarian cancer, but by the 1980s, the connection between diet and ovarian cancer was being studied more actively (4-17). Some dietary factors studied for being protective against ovarian cancer include fish, fiber, vitamins and minerals, beta-carotene from foods, whole grains, and vegetables. Factors being studied for increasing risk of ovarian cancer included high-protein/high-fat diets, meat, coffee, cholesterol, alcohol, obesity, and dairy consumption. In the past 10-15 years, research has begun to suggest that plant foods, in particular vegetables, might decrease risk of ovarian cancer (18-28). This has led to more interest in determining which specific vegetables and nutrients might protect against ovarian cancer. A recent study published in the Journal of Nutrition looked at the amount of specific nutrients and food groups consumed by women with and without a history of ovarian cancer (29). It is hoped that this type of research will help identify what type of diet increases or decreases risk of ovarian cancer. Factors such as reproductive history, age, and gender cannot be changed, but diet and nutrition can! This type of information will allow women to take concrete and practical steps to decrease their risk of ovarian cancer. 

What The Study Found

For this study (29), 124 women with ovarian cancer and 696 women without ovarian cancer were asked about the type of diet they had consumed in the past. Information on other diet and lifestyle factors was collected and accounted for in the study.  Researchers classified the women regarding the types of food they had eaten. Also, the researchers classified the women based on amounts and types of specific nutrients they had eaten. Researchers used this information to examine whether or not eating certain foods and/or nutrients was related to having a history of ovarian cancer. Six important results came out of this study. 

First, the researchers found that women who ate more than 34 grams of fiber per day had less than HALF the risk of ovarian cancer when compared to women who ate less than 19 grams of fiber per day. In other words, eating more fiber DECREASED ovarian cancer risk. 

Second, the researchers found that women who ate more than 18.5 mg of carotenes per day had only ONE-THIRD the risk of ovarian cancer when compared to women who ate less than approximately 7 mg of carotenes per day. In other words, eating MORE carotenes DECREASED ovarian cancer risk. 

Carotenes are a group of nutrients that are found in vegetables and fruits. Beta-carotene is the most well-known carotene. However, there are hundreds of other carotenes in the foods we eat. Most brightly colored vegetables and some brightly colored fruits (orange, yellow, red, green) contain carotenes.

How many mg of carotenes do foods contain?  As an example, one serving of carrots (1/2 cup chopped carrots) contains approximately 41 mg of carotenes. As you can see from this example, it's very easy to get more carotenes in your diet.

Third, the researchers found that women who ate approximately 5 servings of vegetables per day had less than HALF the risk of ovarian cancer when compared to women who ate approximately 2.5 servings of vegetables per day. In other words, eating more vegetables DESCREASED ovarian cancer risk. 

What is a serving of vegetables?  

• 1 cup, loosely packed raw green leafy vegetables or 1/2 cup cooked greens
• 1/2 cup chopped of any other vegetable, cooked
• 6 oz vegetable juice

Fourth, the researchers found that women who ate the most lignans had approximately 60% less risk of ovarian cancer when compared to women who ate the least lignans. 

What are lignans? Ligans are just nutrients that are found in certain foods. As we described above, carotenes are a group of nutrients found in plants. Lignans are a different group of nutrients that are found in plants. Foods with the most lignans include:

• Seeds
• Whole grains
• Fruit, especially fruit with a lot of little seeds, such as blueberries, blackberries, raspberries, strawberries and other berries
• Vegetables

Fifth, the researchers found that women who ate the most stigmasterol had 60% less risk of ovarian cancer when compared to women who ate the least stigmasterol. 

WHAT is stimasterol? This is just a big word for a specific nutrient that is found in some of the foods we eat. The best sources of this nutrient are vegetable fats. In other words, eating plenty of nuts, seeds, legumes, and other sources of plant fats will help you get more of this cancer fighting nutrient into your diet.

Finally, the researchers found that women who ate the most poultry (mostly chicken) had slightly less than HALF the risk of ovarian cancer when compared to women who ate the least poultry. Specifically, women eating an average of 1.5 ounces of poultry per day had slightly less than HALF the risk of ovarian cancer when compared to women who ate approximately one-half an ounce of poultry per day. 

Does this mean chicken helps protect against ovarian cancer. Maybe yes, but maybe no. Other research suggests that saturated fat may INCREASE risk of ovarian cancer (30). One explanation for why eating more chicken reduced the chances of having ovarian cancer is because chicken contains LESS saturated fat than many other foods. For example, replacing high fat beef with chicken will lower the saturated fat in your diet. Instead of simply adding chicken to your diet, it may be of more benefit to replace some of the red meat and other foods that contain saturated fat (cheese, high fat dairy, etc.) with chicken. 

What do these results mean?

Six different important results were revealed by this study. This might make it seem confusing and difficult to incorporate these things into your diet. This is NOT the case. If we assume that the women studied are similar to most women, this study suggests that eating a PLANT BASED DIET decreases risk of ovarian cancer.  

This study shows that several different nutrients protect against ovarian cancer. How do you keep it all straight? The simple answer is that you need to eat more plant foods. In other words, one way to achieve ALL of these goals without thinking about many details is is to eat more plants! All of the nutrients that this study tells us are protective against ovarian cancer are found in plant foods. If you want to meet the levels of nutrients that this research tells us will reduce risk of ovarian cancer, focus you diet around vegetables, fruits, whole grains, and legumes. This research tells us to eat more: fiber, carotenes, lignans, and stigmasterol. All of these nutrients are found in a diet that contains a wide variety of fruits, vegetables, whole grains, and legumes. In addition, the study tells us eating more vegetables, at least 5 servings per day, will protect against ovarian cancer.

How can I change my diet to try to reduce my ovarian cancer risk?

What should you do to help reduce your risk of getting ovarian cancer? According to this study (29), focusing your diet on PLANT foods will be helpful for protecting against ovarian cancer. Use the tips below to accomplish this goal. 

Quick Tips On How to Eat a More Plant Based Diet

• Rely on frozen produce during the off season.
• Add a handful of frozen blueberries, strawberries, or blackberries to your cereal.
• Eat a high-fiber, whole grain cereal, such as All-Bran, Bran-Buds, or Raisin Bran for breakfast. Chose a cereal with at least 6 grams of fiber per serving.
• Stuff your favorite omelet with low-fat shredded cheese, tomatoes, and frozen spinach (that has been cooked and drained). Garnish with strawberries or peaches for a fruit serving.
• Chose whole grain, high fiber breads. Chose bread with at least 3 grams of fiber per serving.
• Read the ingredient list on your grain products such as bread, bagels, muffins, cereals, etc. If you see the word 'enriched' in the ingredient list, it is NOT whole grain. Instead look for words like, 'whole ground', 'stone ground, 'whole grain', etc.
• Keep little 6 oz cans of low sodium vegetable juice handy for a quick serving of vegetables
• Snack on baby carrots and humus; you get both vegetables and legumes with this snack.
• Eat low-sodium bean or lentil soup for lunch - it's quick, delicious and convenient and it counts as a serving of legumes.
• Use canned beans; rinse well and sprinkle on salad to add protein and fiber to your meal.
• Use whole grain pasta instead of plain, white pasta. Try Hodgson Mills brand, which you can buy at most major grocery store chains.
• For a tasty salad, steam several frozen or fresh vegetables (cauliflower, carrots, broccoli, Brussels sprouts), until tender and crisp. Add one-half cup prepared Italian dressing (try Annie's Naturals or Chelten House brands) per pound of vegetables; Mix well and refrigerate until chilled.
• Improve the nutrition value of your family's favorite main dish casserole by adding one cup frozen or canned mixed vegetables. Be sure to look for the veggie blends that include cauliflower, broccoli, and carrots.
• Stuff your favorite potato with antioxidant-rich toppings such as stewed tomatoes, green and red peppers, onions, broccoli, and low-fat cheese. Substitute in a sweet potato and you get even more nutrition value.
• Instead of a plain baked potato, try a baked sweet potato; sweet potatoes are LOADED with carotenes.
• Get acquainted with green leafies. Try adding a few leaves of kale, chard, mustard greens, collard greens, dandelion greens, or any other green leafy food to your regular salad.
• To help yourself focus on variety, be sure to eat a wide variety of 'colors' of foods. Try orange, red, green, yellow, blue, purple, and dark green - carrots, sweet potatoes, peppers, mangoes, papaya, blueberries, eggplant, kale, collard greens, spinach, etc. 
• To get more lignans in the diet, sprinkle ground flax seeds into your cereal, yogurt, fruit smoothies, and salads.
• Sprinkle nuts (walnuts, almonds, etc.) into salads and stir fry dishes. Again, this adds healthy fat to the meal and will increase your intake of stigmasterol (found to be protective against ovarian cancer in this study) and other healthy nutrients.
• Start basing your diet around UNPROCESSED whole plant foods including vegetables, fruit, whole grains, and legumes. Do this instead of basing your food choices around fast food, microwave meals, or instant 'dinner' trays.  These things contain unhealthy fats and too many calories. Plus, they DO NOT contain the healthy cancer fighting nutrients of whole plant foods.
• Learn to love beans. Replace some of your meat dishes with bean-based dishes. Beans are loaded with healthy nutrients, they are low in fat, high in fiber, and one of the best foods you can eat.
• Instead of pretzels or chips, have a small handful of nuts as a snack. Watch portion size, because nuts are high in calories. But, remember, those calories come from HEALTHY fats. Most snack foods such as pretzels do not contain many healthy nutrients found in nuts, seeds, fruits, and vegetables. 
• Replace snack foods with WHOLE vegetables & fruits. Try baby carrots dipped in hummus or salsa for an easy and healthy snack.

Recipes to Help You Eat a Plant Based Diet

Sweet Spicy Kale

Lentil Sweet Potato Soup

Barley Apple Salad

NOTE: If you are in cancer treatment, these diet changes may not be right for you.

References

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Publish Date: 10/2003