Tuesday, October 01, 2013

Peanuts Prevent Cancer?

More nuttiness in the news. Again. 

A new study found girls who regularly ate nuts had healthier breasts as adults. Girls aged 9-15 who reported having nuts or peanut butter twice a week were 39% less likely to be diagnosed with benign breast disease by age 30 than those who never ate them. Benign breast disease, though not cancerous is associated with a slightly elevated risk of cancer later in life so it's worth taking a closer look at this nuttiness. 

This is where another person might put a cute photo of kids eating peanuts. Use your imagination.

The data come from a large national study of 9,000 women who answered questions back when they were still adolescents so unlike other studies they didn't have to recall how often they packed a PBJ sandwich in their lunch box two decades ago. That's good news. The women reported whether they had benign breast disease (BBD) confirmed by a biopsy, so although the evidence doesn't come straight from the medical records it is pretty close and I can't imagine anyone would fudge remembering getting a hole poked in their body. 

Although the media jumped on nuts, the study wasn't just about nuts. The researchers also found potentially good news about other veggie proteins (i.e. soybeans, lentils, corn). Girls who had a daily serving of any one of these proteins at age 14 had a 66% reduced risk of BBD. 

Why the fuss about nuts? 

First off nobody wants to read the headline Vegetable Proteins Fight Cancer!  What the h&** is a vegetable protein anyway? 

More important, the girls seemed to eat more peanut butter than the other veggie protein sources. So at age 11 nuts significantly predicted later BBD but not the other foods individually, perhaps because the girls didn't eating much of the latter. If they had those foods might have won a few headlines too. 

If the girls had scarfed down more soy and beans we also might not have had to read slightly mangled statements: 
This also suggests that beans, lentils, soybeans and corn may also improve breast health down the road, maybe in ten years after the beans have a mid-life crisis and decide to get off the side of the road and start fighting cancer for real. However, researchers are still uncertain at this point whether there is enough evidence to directly make this type of conclusion.Science News World Report
What is certain at this point is that someone still isn't certain about much here. 

But it isn't the researchers. 

In fact the researchers appear quite certain there is not enough evidence to make a causal conclusion or at least not yet:
"These findings suggest that peanut butter could help reduce the risk of breast cancer in women,” said senior author Graham Colditz, MD, DrPH, associate director for cancer prevention and control at Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine. Washington University, St. Louis   
Then Graham, a model of self-restraint thus far, bit off more than he could chew. 
Because of the obesity epidemic, Colditz recommended that girls replace high-calorie junk foods and sugary beverages with peanut butter or nuts.  Washington University, St. Louis   
Maybe he really is an obesity expert in his spare time. Or maybe he's just hungry and his glucose levels and thus self-control plummeted.

Maybe the falling glucose would explain why Graham didn't point out another potential explanation for the link between peanuts and breast health. An explanation that has less to do with nuts than you might imagine. Fortunately WebMD found someone who did offer another explanation, Steven Chen, an associate clinical professor of breast and endocrine surgery in some cancer center in California that I've never heard of before: 
As for how to explain the link? "It's hard to say at this point," Chen said, adding that in countries where less meat is eaten, less breast cancer risk is reported. WebMD
So what he didn't say or at least what didn't get put into print - it wasn't the nuts that produced the health benefits but the lack of meat. Then Steven's glucose levels must have dipped too because after that he started not making so much sense: 
Based on the study findings, he said, teen girls and preteens "shouldn't avoid peanut butter and nuts if they are not allergic." Getting some protein through vegetables, which was also looked at in the study, is a good idea, too, he added.
Shouldn't avoid peanut butter if they are not allergic. Are girls avoiding peanut butter if they aren't allergic? I had no idea this was a problem. Girls, eat your nuts. You wanna get cancer!

There must be something wrong with me this morning. Please. Help. Me. This health news is killing me. You? Does your middle-school daughter eat nuts?



Disclaimer: No I didn't bother reading the journal article this time. I couldn't stomach it.  But all 7 pages could be yours for a mere $39.95! 

Vegetable protein and vegetable fat intakes in pre-adolescent and adolescent girls, and risk for benign breast disease in young women. Breast Cancer Research and Treatment, Volume 141Issue 2pp 299-306.

2 comments:

mommacommaphd said...

Correlation doesn't equal causation!? Who knew!?

Polly Palumbo, Ph.D. said...

Yes in certain circles....that is if you care about such matters! Good to "see" you.