August 24 2010 post. What was supposed to be a quick and easy post turned into a big hairy monster. It all began a few weeks ago (gollywolly, time flies, doesn’t it??? Well, it’s been a busy summer…), when a blog reader/Facebook friend told our Facebook multiple myeloma support group about a rather alarming article (see: http://tinyurl.com/2wrdqqc). In a nutshell, a newly published study shows for the first time that, while pancreatic cancer cells greedily gobble up glucose, they use fructose to divide and proliferate…Eeeek! Fructose? Wait a second. Isn’t that the sugar contained in fruit?!!!
And so my quest began. First, though, I wanted to take a closer look at fructose, about which I knew very little, to be honest. Well, let me tell you, doing research on fructose was like unlocking Pandora’s box…her fructose box (!), that is. Too much information! I became very discouraged, which is partly why it has taken me so long to publish this post…Anyway, here is a summary of what I found:
Many websites declare that fructose is not a natural sugar contained in fruit, as we all have been led to believe!; but is entirely man-made. The sugar contained in fruit is instead, apparently, called “levulose.”
Others don’t even mention levulose…
Most, however, state that levulose is merely a synonym of fructose…
Not content with doing a search in only one language, I also looked at a few Italian websites, finding out that “levulosio” (= the Italian word for “levulose”) is simply the ancient word for “fructose” and is no longer used. Not very helpful. Uffa.
Well, with the levulose-fructose issue unresolved, I took a deeeeep breath and began reading the full pancreatic cancer study, which a lovely blog reader (thanks!) sent to me. The more I read, the more the distinction between fructose and levulose (if there is any!) became totally irrelevant. Phew. Relief! This saga, by the way, has taught me a good lesson: read the full study FIRST!
You see, there is no mention of the word “fruit” in the full study. No apples. No pears. No gooseberries. No kiwi. What instead is mentioned frequently is “refined fructose,” and refined fructose, I can assure you, does not grow on a tree or on a bush. It is the end result of a chemical process. So there is no need to panic and toss all our fruit into the rubbish bin.
Let’s see. From what I read, REFINED fructose has been stripped of all its nutrients. Nothing natural in it. But worse, it can cause all sorts of, er, not-so-lovely things, such as high triglycerides, metabolic dysfunctions, liver disease and obesity. At the top of the “refined fructose” list are agave nectar or syrup (up to 92% refined fructose when heated!) and high-fructose corn syrup (= HFCS). I was surprised to note that HFCS can be found in almost everything, not just in soft drinks but in yoghurt, industrial bread, cookies, salad dressings and ketchup. It’s really hard to avoid…(see my P.S. at the bottom of this post, though).
Okay, my long and rather fruity introduction to the fructose study has gone on long enough. Let’s take a look at the full study. First, here is the link to the abstract: http://tinyurl.com/38f2oxm In the full study I read that Increased refined fructose consumption, in particular, has been highlighted as conferring greater pancreatic cancer risk than other sugars in several recent large epidemiologic studies. Relax, Margaret: refined fructose, not peaches and blueberries…
And, a bit further on: We recently observed that mean circulating fasting fructose levels were 2.5 times higher in pancreatic cancer patients in comparison with fasting serum fructose levels in healthy subjects who were in the 0.5 to 1.0 mmol/L range. The role, if any, of fructose as a substrate in cancer is poorly understood. The present study shows that pancreatic cancer cells grow in a range of fructose concentrations that are attainable with the current Western diet and at equivalent rates to glucose. The researchers also found that pancreatic cells use fructose and glucose in different ways, as we will see in a minute. So let’s plod on…
Results: the researchers measured the in vitro proliferation rates of several pancreatic cancer lines immersed in a different fructose and glucose concentrations and compared them to glucose-bathed and high-glucose-bathed cells. They found that the pancreatic cancer cells grew in both glucose and fructose…in the same concentrations. And they also found that normal pancreatic cells grew in both glucose and fructose.
But then they checked the cancer proliferation rates and discovered that, even though pancreatic cancer cells prefer dining on glucose, they can also uptake and use fructose for growth. In order to understand this mechanism, the researchers examined how cancer cells metabolize the two sugars. Skipping the technical bits, flip flip flip, it turns out that, unlike normal pancreatic cells, the cancer cells metabolized fructose at 250% higher rates than glucose. Holy cats!
They also found that, after gorging themselves on refined fructose, the pancreatic cancer cells produced more uric acid, a finding that further supports the researchers’ theory. Now, this part gave me a lot of food for thought. You see, one of my routine tests is uric acid (mine has always been way within the normal range). It is one of the first results that my haematologist checks carefully. She believes that it is a VERY important test for myeloma. Well, this pancreatic cancer study makes me wonder if refined fructose is bad for myeloma folks, too. In the absence of a myeloma-refined fructose study, I will simply assume that it is (…bad for us, I mean…). I am sooo relieved that I gave up soft drinks a few years ago. I don’t touch the stuff now. And I have never even tasted agave nectar.
Now, let’s have a look at the Discussion part. According to conventional wisdom, until now there has been no difference between glucose and fructose in terms of feeding cells and so forth. This study’s data, however, puts things in a new perspective: pancreatic cancer cells prefer to use fructose to proliferate. So there is a difference. For those who are more scientifically-minded: fructose potently induces TKT expression and activity to aid metabolism of fructose in the PPP.
The researchers conclude that fructose is a particularly significant dietary sugar component with important implications for patients with cancer, particularly given the significant dietary change that has occurred in human fructose consumption since the mid-20th century. Our findings provide important insights into recent epidemiologic studies that have identified refined fructose as an independent risk factor for pancreatic cancer, and identify fructose-mediated actions as a novel therapeutic cancer target.
So pancreatic cancer cells thrive on glucose (=ordinary sugar) BUT use refined fructose to divide and proliferate. This challenges the common wisdom that sugar is just…sugar.
On a practical level, what does this mean? Yes, here we are talking about pancreatic cancer cells, not myeloma ones. However, based on the above-mentioned uric acid titbit, I wonder if a myeloma-refined fructose study would churn out similar results. Impossible to say. In the meantime, however, it is probably a super good idea for us to cut down on all processed foods, soft drinks and sweeteners. You never know…
Hmmm, hey, do you want to bet that now the pharmaceutical companies are scrambling to find a drug or a molecule or a hoojamaflip that will stop pancreatic cancer cells from using refined fructose to reproduce? Hah! Mark my words…
By the way, since my next door neighbours are putting in a new bathroom on the other side of my study wall, I apologize for any possible repetitions in this post…But let me tell you: the drilling noise is deafening. In fact, at times I feel as though the masons are drilling holes right through my brain!
P.S. Decline in the use of high-fructose corn syrup: http://tinyurl.com/38jv3ae
P.P.S.S. Helpful website on triglycerides, fructose etc. http://tinyurl.com/59uosc