Friday, March 22, 2013

The Myth of Sugar-Loving Tumors

I went out to dinner with a friend of mine last night who asked me if sugar feeds tumors. He had seen some sort of presentation where someone showed sugar being taken up by tumors.   I see these kinds of things on Facebook posts all the time and scroll by.  But when friends pose these questions to me over a plate of pasta, I take the concern a little more seriously.  
                So what are the facts here? Well, cancer cells and tumors need calories and nutrients just like the healthy cells in our bodies.  While cancer cells do feed off sugar, healthy cells do too. So yes, if you give a tumor sugar in a petri dish it will surely be taken up by the cancer cells – but so will all the other cells of your body.  It also makes for some nice scary pictures to post on Facebook and for an overly simplistic message about how cancer cells operate.
                Research shows that eating sugar doesn’t speed up cancer growth.  If you want to shut off what feeds cancer, you have to shut off what feeds all of your cells. You would starve and kill the cancer cells but you would also starve and kill healthy cells and die.  Some research shows that there may be some sort of link between high insulin levels and growth of some cancers.  Some people pump out too much insulin when they eat too many carbohydrates.  But many of us have normal insulin levels. 
                We do know that obesity may be a risk factor some cancers. So eating too much sugar and other calorie dense foods could be an indirect factor in some cancers. In fact, one of the first recommendations by the American Institute for Cancer Research for cancer prevention is to be as thin as possible without being underweight.  They also recommend eating fewer calorie dense foods – including sugar sweetened beverages. These foods can increase weight.  It’s the weight gain that can lead to many problems – including too much insulin – and that increases the risk of some cancers.
                But notice I said some cancers.  And this is another area of misconception about cancer. Cancer is not just one disease. While there are common themes to all cancers – such as all cancers start with some sort damage to genes –  risk factors and causes of each of the cancers are not always the same. For instance, the human papilloma virus is a cause of cervical cancer and possibly some oral cancers but not of other types of cancers.  Weight gain seems to be a risk factor for cancers in the esophagus, pancreas, colon/rectum, endometrium, kidney, gallbladder, and postmenopausal breast cancers. It may not be much of a risk factor for cancers in the lung, ovaries, or stomach.
                The bottom line is that we should all be moderate with sugar. But it is the not the tumor-feeding fiend a lot of people make it out to be.  You can also check out this excellent explanation of this myth on the Mayo Clinic website.
Beth Kitchin PhD RD
Assistant Professor, Nutrition Sciences
University of Alabama at Birmingham 

Monday, March 18, 2013

Hydration Nation: The 8 Cups of Water a Day Myth

Most people have heard that they need to drink 8 cups of water every day to be healthy. And water is crucial to helping our bodies work right – so it’s not surprising that water is responsible for 60% of our body weight.  But do you really need to guzzle at least 8 cups a day? Our bodies lose water every day through the kidneys in the urine, from the lungs when we breathe, and through sweating. The typical person does lose about 8 to 12 cups of water a day through these routes but, as it turns out, there are many ways you can replace that loss.
Restoring Water:
Ø  Milk & Juice: When you drink milk or juice not only are you getting vitamins, minerals, and in the case of milk, protein, you’re also replacing water loss. Both milk and juice are over 80% water so they can really make a dent in body water needs.
Ø  Coffee & Tea. These two always surprise people because many people are led to believe that the caffeine in caffeinated beverages makes them lose all the water in the beverage & then some causing an overall water deficit. Not so! Yes, it is true that caffeinated beverages are not as good as non-caf in helping you hydrate but you still get some hydration effect. In other words, you urinate a little more with caffeinated beverages but remember, you're getting a lot of water in that coffee, tea, or soda and you retain over 50% of it. Researchers have also shown that most people adjust to the caffeine level in their drinks so over time, so the caffeine does not have as much of an effect on your body. After about 3 to 5 days of drinking caffeinated beverages, the body adjusts and there is no additional loss of urine when compared to decaffeinated beverages.  
Ø  Soda.  Even soda can help you rehydrate – it’s mostly water. Your best bet is diet sodas so that you’re not adding in empty calories.
Ø  Fruits & vegetables. Fruit & vegetables contain a lot of water. Strawberries, watermelon, lettuce, cabbage, celery, spinach, & broccoli are particularly high at over 90% water. The water content of most other fruits & vegetables is over 80% so they are also good sources. For many people, fruits & vegetables can contribute 1/3 or more of their daily water needs!
Ø  Other foods. All foods contain some water, but notable water contributors include yogurt, cottage & ricotta cheeses, fish, chicken, and pasta.
Ø  Water: Water is the best hydrator – it empties from the stomach quickly and makes its way to the large intestine where it can be absorbed quicker than the other fluids.
Ø  Thirsty? Thirst is actually a pretty good guide to whether or not you need more fluids – except in older people.
Ø  Check Your Urine. The best way to tell if you are getting enough fluids is to check your urine. If you are well-hydrated, your urine will be very pale. If you need fluids, the urine is dark yellow and low in amount.
While drinking water is still a good idea, you don’t have to feel like you’re drowning in it or lug a massive, back-breaking water jug around all day long.  All beverages (except alcohol) count toward your total 8 to 12 cups and eating a lot of fruits and vegetables will also help keep you hydrated.
Can you get too much water? Surprisingly, yes! People who chug water excessively can actually dilute out their blood sodium levels to a dangerously low level. The fancy name for this is hyponatremia. Some of the symptoms can mimic dehydration – muscle weakness, muscle cramps, confusion, and decreased consciousness. It can result in death!
Beth Kitchin PhD RDN
Assistant Professor, Nutrition Sciences
University of Alabama at Birmingham