SkepticRD really, really needs to stay off the Facebook before she goes to bed, as I typically am going to find something that keeps me awake at night. Fortunately there is enough there to promote Skeptical Inquiry while tossing and turning. Last night’s mind wanderings were inspired by this: little picture about bananas.
Yes, the whole Tumor Necrosis Factor (TNF) thing set off warning bells in my head, because as a dietitian who works with a mostly elderly population these days, I wind up working with people who have cancer. And people who have cancer, often have increased TNF secretion. Many times people with cancer don’t want to eat, and one of the reasons is that this lovely TNF is inducing a condition called cachexia –a wasting syndrome where you lose weight, your muscles shrink, you get weak and tired, and you lose your appetite—all without trying. I have also been around long enough to have worked with AIDS patients before the newest class of anti-virals became available, and I saw cachetic patients more than I ever cared too. Not only is cachexia a nightmare for the patient, it’s a nightmare for the people treating them because even when we try to cram protein and calories down their throat the person will continue to lose weight until we find a way to treat whatever is causing the problem. The risk of death increases dramatically, so much so that back in the “old days” if a person with AIDS came to my office wanting advice on weight gain, we would have a nice conversation about ways to increase their protein and good fat intake, and I knew that I would probably never see them alive again. So SkepticRD was also screaming at the computer and sending Cats of SkepticRD flying out of the room , as the sound of “Why in hell would anyone want to increase this?” rang out across Skepticville.
Fortunately, the Michael Simpson over at Skeptical Raptor (Link) was already ahead of me on this one. First, study itself is eviscerated (hah!), including pointing out that the authors themselves do not make any claim about TNF being in bananas. Second the Raptor tears apart (I'm having too much fun here!) the pseudoscientific claims associated with TNF (including reminding us that even if the bananas had it, it would break down in your digestive system!). Third, after the disemboweling is over (thank you Thesauras.com!) it is pointed out that TNF is associated with such lovely autoimmune conditions such as rheumatoid arthritis and inflammatory bowel disease. So, even if TNF wasn't broken down by the digestive system I don't think I would be voluntarily taking it into my body any time soon.
Do bananas have some other good qualities? Sure, they have some potassium and soluble fiber and B6, but so do lots of other fruits and vegetables. SkepticRD tends to shy away from bananas because they usually contain about 25-30 grams of carbohydrate per banana, and since that is my max meal requirement to keep blood glucose levels under control, I would rather eat a cup of berries and only get about 10-15 grams of carbohydrate. Which reminds me of another pet peeve of mine, the inability of many internet denizens (and people in general) to be able to compare amounts and/or be aware that HOW MUCH they eat makes a difference. So I will frequently hear some variation of "I don't eat bananas because they have too much sugar. I eat berries instead." First of all notice the difference between my statement and the second statement, one statement makes a judgment based on a quantifiable amount, the other makes a judgment based on something vague. And if by “eating berries” they mean “I eat a flat of berries over a two day period” you aren’t controlling your carbohydrate intake. In other words, you can’t say something is good or bad for you unless you have a way of quantifying it. (And no, SkepticRD is not exaggerating when I talk about the person who ate a flat of berries by himself in two days.)
One of the other problems with the internet meme listed above is that it continues to feed the myth that you can boost your immune system. First of all, if you are a healthy individual you cannot boost your immune system above baseline. Now, I know there is going to be an immediate squawking about where people state that we in the United States don’t get enough sleep, or exercise, or eat right, etc, Well, it is true that if you aren’t getting enough sleep, etc your immune system will be faulty, but you improve it by—finding ways to improve your sleep, find ways to improve your overall diet, etc. There is no one food, one vitamin, one probiotic, or even one exercise that will improve your immunity if you do not fix the original problem. Also, keep in mind that if a healthy person does boost their immune system they are actually promoting inflammation, very likely increasing your risk for heart disease, strokes, and blood clots. (Link).
Take home message—even if bananas had TNF that would survive your digestive system, chances are you could be putting yourself at risk for autoimmune disorders. Include bananas in your daily carbohydrate allowance if you wish, but be careful of amounts.