Cancer and Food FAQs
Is it true that caffeine-containing beverages act as diuretics and cause a fluid loss?
Many people use caffeine-containing beverages like coffee, tea, or pop to wake up, help fight fatigue, and improve concentration. It is widely believed that consuming caffeine has a diuretic effect and causes people to urinate more, thereby not allowing these beverages to be counted toward the day’s fluid intake. However, recent research supports that caffeine only has a diuretic effect when consumed in large volumes, which would be defined as greater than 500-600 mg of caffeine.
To help you determine your typical caffeine consumption, it is helpful to know that the average 8 oz cup of coffee contains 130 mg of caffeine, the average 8 oz cup of tea contains 50 mg of caffeine, and the average can of pop contains roughly 70 mg of caffeine.
Although caffeine-containing beverages do not generally increase urinary frequency, consuming too much caffeine can cause jitteriness, make you anxious and irritable, and can cause difficulty sleeping. While it is safe to consume low amounts of caffeine, water is always the preferred hydration source. It is cheap, contains no calories, and is widely available.
Does sugar feed cancer?
It is a common myth in the cancer community that consuming sugar through your diet will feed cancer cells in the body. Though the origination of this myth is unknown, it is partially thought to be due to how PET scans function. PET scans are a type of scan used to look at where cancer is in the body.
In order to do a PET scan, the patient is injected with a radioactive glucose tracer, which is then taken up by all cells in the body. The cells that are the most metabolically active – or require the most energy – will take up more of this tracer and this part of the body will “glow” on the scan. This “glowing” on the scan represents cancer cells.
However, as previously mentioned, EVERY CELL IN THE BODY uses glucose (sugar) for energy, whether we’re talking about our normal, healthy cells or cancer cells. Some people think that if they cut back on the dietary sugar/carbohydrates they consume, it will help starve the cancer cells. This is mistaken, though, since it also decreases the glucose energy available to our healthy cells. Our bodies are extremely resilient and since it needs glucose for energy to function, it will begin to break down muscle and fat stores to provide this glucose if we don’t consume enough through our diets.
With that being said, it is still important to limit simple sugars you eat like pop, juice, baked goods, chocolate, other sweets, white breads, white pastas, and refined cereals like rice krispies and many kids’ cereals. Any time we consume carbohydrates, it causes insulin to be released in our bodies. Insulin is a storage hormone that essentially works as part of a lock and key system. Insulin can be thought of as being the key, and a cell in the body can be thought of as having a lock on it.
When carbohydrates are eaten, insulin is released and “unlocks” the cells to allow the sugars from the carbs enter the cell to provide energy. The problem is insulin functions as a growth hormone and can potentially cause growth of tumor cells. When people are diagnosed with type 2 diabetes or insulin resistance, it means their body’s cells resist allowing insulin “unlock” the cell, so the body has to pump out even more insulin than normal for the cell to finally be “unlocked”.
Being overweight or obese is a risk factor for insulin resistance, which is why many cancers such as colorectal, endometrial, and pancreatic are associated with carrying excess body weight.
We’ve already determined that our bodies need us to consume carbohydrates in our diets for energy, and if we don’t consume enough, our bodies will break down our muscle and fat tissues to provide it. However, whenever we eat carbs, it causes insulin to be released, which we know can promote cancer growth. What do we do?
The best thing you can do is focus on making healthy carbohydrate choices, such as from whole grains, fruits, and vegetables. These types of foods innately have many anti-cancer properties to them because of their high phytochemical content, and they also have the added benefit of the fiber they contain will slow down digestion and reduce the amount of insulin released. While fiber can slow down gut transit time, protein and fats in the diet also carry the same function.
Therefore, every time you’re eating – whether it’s at mealtime or snack time – make sure you have included some sort of fiber, protein, or fat in your food choices. For example, instead of having plain club crackers for a snack, choose a whole wheat cracker and/or top the cracker with peanut butter or a little bit of cheese. If you like to snack on chocolates, mix chocolate chips into a trail mix with some nuts and dried fruits. Pairing your foods can be an often overlooked but smart way to snack.
To summarize, dietary sugar/carbohydrates do not “feed” the cancer cells any differently than it feeds our normal, healthy cells, so it’s not possible to starve the tumor through restricting carb intake. Since we need carbohydrates to function, choose wisely and incorporate a variety of fruits, vegetables, and whole grains into your diet. Whenever you eat a meal or snack, also work to incorporate some sources of fiber, protein, or fat to slow digestion and reduce the body’s insulin release.
I have ER+ breast cancer. Should I avoid soy?
This is a common question we hear from some of our breast cancer survivors. They are concerned that since soy has weak estrogen-like properties and their cancers are fueled by estrogen, all soy needs to be eliminated from the diet to reduce the risk of a breast cancer recurrence.
Fortunately, breast cancer research in this area does not support this conclusion and does not recommend eliminating soy from the diet. In fact, a study published in the Journal of the American Medical Association in 2009 determined soy food intake is associated with decreased risk of death and of cancer recurrence. When females consume soy in their teenage years as their bodies are developing, it can actually help prevent the development of breast cancer later on in life.
For breast cancer survivors, it is recommended to consume no more than three servings of whole soyfoods per day. Servings are equivalent to: ½ cup of green soybeans, tofu, TVP, or tempeh; ¼ cup of soynuts or soy flour; or 1 cup of soymilk. It is strongly recommended to avoid soy supplements in the form of isoflavones, as it is unknown how the body responds to those high dose supplements.
Choosing whether to incorporate soy into the diet can be a deeply personal issue. Even after hearing it is safe to consume soy, some women are still more comfortable with completely eliminating it from their intake. Only you will know what you are comfortable with and how you would like to approach your diet after receiving a breast cancer diagnosis. However, remember to look at the big picture when you’re striving to make changes.
Making changes such as eating 8-10 servings of fruits and vegetables per day, eating 1 serving of cruciferous vegetables (broccoli, cauliflower, cabbage, Brussels sprouts) daily, limiting processed food intake, exercising 30 minutes at least 5-6 days per week, and incorporating stress relief techniques are heavily supported in research for reducing risk of breast cancer and are part of this ‘big picture.’
What supplements should I take during treatment?
There are no supplements specifically recommended to take during cancer treatments. Antioxidant supplements like vitamin C, vitamin A, or selenium are frequently considered by cancer patients due to their function as a defense system. However, these can be contraindicated during active cancer treatments since they can interact with and reduce efficacy of treatment.
If you have side effects from the cancer or its treatments and aren’t eating a well-balanced diet, it would be recommended to take a multi-vitamin to act as an “insurance policy” and cover your nutritional bases until intake is more normal. Other supplements may be appropriate for you based on your typical eating habits, any food aversions, your age, your gender, and other medical conditions. Since dietary supplements can interact with your cancer treatments or medications, it is recommended that you consult with your physician and dietitian on supplements you’re taking or considering taking.
Is organic food really better for me than conventionally grown?
This question is an ongoing topic of debate in research. A large study published in the Journal of Clinical Nutrition in 2009 examined the previous 50 years' worth of scientific articles about the nutrient content of organic and conventional foods. The researchers concluded that organically and conventionally produced foods are relatively comparable in their nutrient content. Research in this area is ongoing.
The research available on this topic tells us that organic fruit and vegetables generally are higher in vitamins, minerals, antioxidants, and other healthy nutrients when compared with conventional produce. Studies tell us that organic fruit and vegetables have higher levels of vitamins C and E, iron, magnesium, carotenes, and some polyphenols. Carotenes and polyphenols are groups of nutrients found in fruit and vegetables and are believed to reduce disease risk.
People choose to ‘go organic’ for a variety of reasons, such as wanting to limit their exposure to food additives or pesticides, to be more environmentally conscious, or because they believe organic foods are healthier than conventionally grown foods. Because organic farming is a much more time- and labor-intensive than conventional farming, organic products tend to be more expensive than their conventionally grown counterparts.
If you want to purchase more organic products but do not have an endless budget, consider purchasing produce from the ‘Dirty Dozen’ list. The Dirty Dozen are the twelve fruits/vegetables that generally have the highest pesticide content and are as follows: apples, strawberries, spinach, grapes (imported), potatoes, lettuce, celery, peaches, nectarines (imported), sweet bell peppers, blueberries (domestic), and kale/collard greens.
In opposition lies the ‘Clean Fifteen’, which, as you can imagine, are the fifteen produce sources with the lowest pesticide content. Produce making the Clean Fifteen list are: onions, pineapples, asparagus, mangoes, cantaloupe (domestic), sweet potatoes, cabbage, mushrooms, sweet corn, avocados, sweet peas, eggplant, kiwi, watermelon, and grapefruit. This list can also be found on the Environmental Working Group’s website.
Hundreds of research studies show that the more fruit and vegetables a person eats, the lower his or her risk of cancer and other diseases. These studies have been conducted on the general population, most of whom eat conventional produce. If the harm of the pesticides outweighed the benefits of these foods, we would not see the consistent protective effects of eating these foods (fruits and vegetables). But we do see these protective effects.
To sum up: Incorporate organically grown produce as you are able but remember that the total number of fruit/vegetable servings outweighs the method of farming used to grow these products. The most important part about the organic vs conventional debate is the need to actually increase fruit and vegetable intake, and the recommendations to reduce risk for developing cancer are consuming 8-10 servings per day.
