Low-carb diets and cancer prevention

[Robert Z]

I noticed this paper the other day and find it to be rather amazing in its implications.

 

From the Journal of Nutrition and Metabolism:

 

“Over the last years, evidence has accumulated suggesting that by systematically reducing the amount of dietary carbohydrates (CHOs) one could suppress, or at least delay, the emergence of cancer, and that proliferation of already existing tumor cells could be slowed down. This hypothesis is supported by the association between modern chronic diseases like the metabolic syndrome and the risk of developing or dying from cancer. CHOs or glucose, to which more complex carbohydrates are ultimately digested, can have direct and indirecteffects on tumor cell proliferation: first, contrary to normal cells, most malignant cells depend on steady glucose availability in the blood for their energy and biomass generating demands and are not able to metabolize significant amounts of fatty acids or ketone bodies due to mitochondrial dysfunction.Second, high insulin and insulin-like growth factor (IGF)-1 levels resulting from chronic ingestion of CHO-rich Western diet meals, can directly promote tumor cell proliferation via the insulin/IGF1 signaling pathway. Third, ketone bodies that are elevated when insulin and blood glucose levels are low, have been found to negatively affect proliferation of different malignant cells invitro or not to be usable by tumor cells for metabolic demands, and a multitude of mouse models have shown anti-tumorigenic properties of very low CHO ketogenic diets. In addition, many cancer patients exhibit an altered glucose metabolism characterized by insulin resistance and may profit from an increased protein and fat intake.

 

In this review, we address the possible beneficial effects of low CHO diets on cancer prevention and treatment. Emphasis will be placed on the role of insulinand IGF1 signaling in tumorigenesis as well as altered dietary needs of cancer patients...”

 

Is there a role for carbohydrate restriction in the treatment and prevention of cancer?

[RonaldS]

Interesting. I didn't read the whole thing, but it's important to pay attention to the fact that they're not stating that carbohydrates are causing cancer, but rather that cancer cells seem to receive glucose preferentially, and it appears to aid in the proliferation of cancerous cells and the growth of the tumor.

 

I make this point because people have reading comprehension issues, especially on message boards, and will take away from the study 'carbs cause cancer'.

 

Glucose molecules bind together to form glycogen, which is then stored in muscle tissue. When you need to quickly contract a muscle, exercise, whatever, that is the first place muscles are getting their energy from. In other words, it's sorta important.

 

Anyway, as with many dietary issues, IMO, it isn't the molecule (carb, fat, protein) in and of itself that's the problem. It's excessive amounts, unused, out of balance, etc that hurts.

 

Eat a balanced diet, get plenty of water, and exercise regularly...you'll be Kool and the Gang.

[Robert Z]

Eat a balanced diet, get plenty of water, and exercise regularly...you'll be Kool and the Gang.

 

I suspect that the question of what constitutes a balanced diet is still in play. In particular, balanced for what? One can't help but wonder about the argument that we didn't evolve while eating processed grains and high-carbohydrate diets. We have probably lived on ketogenic diets for most of human history. This seems to suggest that mild ketosis could be our normal metabolic state. While things like wheat and potatoes solved the starvation problem, could it be possible that they come with a price?

 

This is all way out of my league but it is certainly fascinating to consider. Could our high-carb lifestyles literally be providing a nursery for and feeding the cancers and that everyone hopes to avoid?

 

What clued me into this was a news report recently about a man who claims to have cured himself of cancer by going on an extreme low-carb diet. Based on the paper in hand, that claim doesn't seem entirely impossible.

Edited July 13, 2013 by Robert Z

[EasyHeart]

I listened to a lecture by a cancer researcher a few months back and he said that a high starch/low fat diet will reduce your risk of heart disease and a high fat/low starch diet will reduce your risk of cancer. (Protein is neutral). So if heart disease runs in your family, go low fat; if cancer runs in your family, go low starch.

 

The most important thing to take away from this research is that -- regardless of what the 'public health' officials tell you --- there is no one perfect diet that will result in optimal health for all human beings. Each of us has to take responsibility for our own health. Age, lifestyle, genetics, and lots of other things affect what diet is best for you.

[Robert Z]

This is all controversial, but it appears that a low-carb, high-fat diet, isn't inherently dangerous IF the total caloric intake is reasonably limited. The key is that the fat is immediately needed for energy. But you have to be slightly ketogenic or your body goes for carbs and not the fat first.

 

One bit of evidence for this is the fact that you can get skinny on a high-fat diet.

 

The biggest problem with fats seems to be that we eat enough carbs to sustain our energy needs and then consume fat on top of that; or, we simply eat too many calories.

Edited July 13, 2013 by Robert Z

[RonaldS]

Robert...you nailed it with your last sentence.

[Robert Z]

I think we have been increasing in size for so long that people are actually starting to lose perspective. After slowly losing weight and working out for over two years, I am just now into a slightly athletic build with a moderate BMI - right at the high end of the healthy region and on the edge of overweight. Given my muscle mass I am probably almost exactly in the center of the area defined to be the correct body fat. But people are constantly telling me that I am getting too thin! No, I'm really really not. I just now pass the old pinch test - if you can pinch more than an inch on your belly, you are overweight.

 

Needless to say, the amount of calories that many meals contain is just nuts. I almost never eat more than 1800 calories a day any more. But many of the big burgers at top chains are at or in excess of 1100 calories - just the burger! And even a 10 piece bag of chicken bites runs a whopping 1300 calories. We are being force fed [bliss point seduction] like a fatted calf getting ready for slaughter - or perhaps more appropriately, like heroin addicts being fed heroin.

The Highest-Calorie Item at 10 Fast-Food Chains - Yahoo! Finance

 

How Food Scientists Engineer the “Bliss Point” in Junk Food

http://www.nextnature.net/2013/02/how-food-scientists-engineer-the-bliss-point-in-junk-food/

 

And I think FitChick made a really good point in another thread: You can't expect to exercise your way to a healthy weight. When it comes to weight, first comes diet, then exercise. I know of several people right now who eat way to much and think they can run or dance away those calories. But it is all too evident that they don't. When you do the math, very few people would even have the time to exercise away a 2500 or 3000 calorie a day diet.

Edited July 13, 2013 by Robert Z

[RonaldS]

To respond to your point about defining balance...well, that's difficult to do. It's different for everybody. There's certainly no formula.

 

Regarding the evolution of our diet, without going into a whole big dissertation, look at it this way: do we have mechanisms to metabolize/utilize carbohydrates? Of course. Fats/lipids? Of course. Proteins and amino acids? Of course. OK...so it's all in play, meaning we are equipped to eat pretty much whatever we can get ahold of. We are generalized opportunistic omnivores, and thought our evolutionary history, we just eat whatever is around. The more abundant and easier to get, the better.

 

So, we're set up to eat pretty much whatever. Where we've gotten into trouble is that many of the foods we eat are packed with carbs, packed with fats, packed with proteins...well, more the first two. All of those sugars and fats = calories. When we are not using that energy for something, it gets stored. It gets stored, we get fat. We eat too much and move too little.

 

As for the article, I didn't have time to read it, but I am curious if cancerous cells can get glucose preferentially. If that were the case, I could see how a high carb diet is going to exacerbate the growth.

 

Balance, I guess, would just mean 'reasonable'. People need to cut portion size WAAAAAY down. We don't need to eat until we're full. Just eat enough. For me, I get tons of carbs in my diet, but I'm active all the time, so my body just burns through it. So, I'm using it, not storing it. At the same time, I'm also not sitting there making milkshakes with Oreos and Mountain Dew. Sensible. Reasonable. And don't eat stuff high in sugar and fat regularly. Pretty simple.

[Robert Z]

I am curious if cancerous cells can get glucose preferentially. If that were the case, I could see how a high carb diet is going to exacerbate the growth.

 

From the quote

contrary to normal cells, most malignant cells depend on steady glucose availability in the blood for their energy and biomass generating demands and are not able to metabolize significant amounts of fatty acids or ketone bodies due to mitochondrial dysfunction

 

If I understand your meaning, the answer seems to be yes. Perhaps more to the point, while pathways for metabolic processes are generally known for fatty acids and ketones while in a ketogenic state, cancer cells specifically cannot process either. So, if I understand this, a ketogenic diet can in principle starve the cancer and prevent growth. Glucose is absolutely required for most cancers to multiply.

 

Late edit: Oh wait, I think I see your meaning. Can cancer rob your glucose from other processes? Would it really matter as long as there is enough glucose to satisfy the momentary demand at any time?

Edited July 13, 2013 by Robert Z

[RonaldS]

From the quote

 

 

If I understand your meaning, the answer seems to be yes. Perhaps more to the point, while pathways for metabolic processes are generally known for fatty acids and ketones while in a ketogenic state, cancer cells specifically cannot process either. So, if I understand this, a ketogenic diet can in principle starve the cancer and prevent growth. Glucose is absolutely required for most cancers to multiply.

 

Late edit: Oh wait, I think I see your meaning. Can cancer rob your glucose from other processes? Would it really matter as long as there is enough glucose to satisfy the momentary demand at any time?

Yeah, it's a matter of if the cancerous cells can get it before other cells. Admittedly, I'm very rusty on my bio-chem and physiology. A lot of what a cells needs and gets is determined by signaling from transmembrane proteins, so if a certain cell or cell type is getting a molecule preferentially, it's signal is overriding or canceling out another signal from another cell (or preventing those signaling proteins from even being activated?). Again, it's been a long time, so I can't remember the details.

 

Either way, it's interesting. I would think if the cancer cells are just getting glucose through the normal pathways as a function of normal processes, and other cells are getting glucose the same way, it could be a situation where an excess of carbs is acting to 'feed' the cancerous cells. If the cancerous cells are getting glucose preferrentially, that could be troublesome, because then limiting glucose would of course be detrimental to cancerous cells, but also other cells that need it, given that the cancerous cells are taking it first.

 

In other words, I need to shut up and read the article.

[RonaldS]

So, I dug out my Powers and Howley 'Exercise Physiology' textbook, 7th Ed from 2009....so, fairly up to date.

 

Anyway, I was curious about what constitutes a 'balanced diet'. According to them, an adult should get 45-65% of their calories from carbs, 20-35% from fats, and 10-35% from protein.

 

Now, those are pretty broad ranges, and where an individual fits within those ranges is obviously going to depend on a lot of factors (sex, age, activity level, etc). Now for me, I'm extremely active. I did a comprehensive diet analysis on some pretty crazy program to get an idea of what my caloric allowance is. Believe it or not, I am probably at about 4500 kcal/day. So, I'm lucky...I can eat pretty much whatever I want. And because I am athletic and play a lot of sports as well as just have a high activity level in general, I can have a diet where I'm probably getting 60+% of my calories from carbs. That means I can eat a lot of candy (and I sorta do) as well as rice and pastas, breads, whatever. It just doesn't have a chance to get stored. It's like pouring gasoline on a fire. I burn through it instantly.

 

Robert, you are spot on with your points about portion size and the number of calories in most people's meals. Incredible. And FitChick is right. You have to moderate caloric intake, fix your diet, and essentially take in LESS than you use if you want to lose weight. Once the weight is lost, you can take in = to what you use. Of course, the exercise is going to allow you to take more calories in, but if the goal is weight/fat loss, you have to be in a deficit for a little while.

 

Finally, regarding this thread...I just think the title is misleading. Carb reduction can seemingly inhibit tumor growth, if what the study shows is true, but it's unlikely that carb reduction is a cancer preventative. That implies that carbs are causing cancer. No. Carbs are essential for good metabolic activity, health, etc. your body needs carbs. Remember, cancer is just cells that had a genetic alteration that deprograms apoptosis, or programmed cell death. Cells have mechanisms to self-destruct when things go wrong. In cancerous cells, that is deactivated and the cells are allowed to replicate. Just pointing that out because of the misconceptions about what cancer truly is.

[FitChick]

I think fat people have higher rates of cancer because fat increases estrogen levels and hormonal imbalances are a cause of cancer. Fat people tend to eat more junk food, processed food, salt, fat and sugar. Not good for preventing any type of disease.

 

All things in moderation.

[Robert Z]

Finally, regarding this thread...I just think the title is misleading. Carb reduction can seemingly inhibit tumor growth, if what the study shows is true, but it's unlikely that carb reduction is a cancer preventative. That implies that carbs are causing cancer. No. Carbs are essential for good metabolic activity, health, etc. your body needs carbs.

 

I disagree with your basic objection. Firstly, if a cancer is unable to grow and spread, then this does amount to prevention. It doesn't imply that carbs create the cancer, but they may make cancer possible. Note that insulin plays a critical role in the spread of cancer cells as well.

 

I would add that a paper published in a major medical journal used the word, prevention, in their title. If it passes peer review for the Journal of Nutrition and Metabolism, then I think it passes muster for LS.

 

Your argument about carbs completely ignores the plethora of information in regards to ketogenic diets. Beyond a minimum, we don't necessarily need carbs to function and be healthy; that is, it may not be critical that carbs constitute the major part of our diet.

 

The popular definition of a healthy diet is basically the Pritikin diet. This was just one of many diet plans to come out during the 70s and 80s. By no means are these conventions written in stone. As with all sciences, our understanding of nutrition and metabolism are still in a high state of flux.

Edited July 14, 2013 by Robert Z

[RonaldS]

Here's what I took from skimming the study: the role of carbohydrates in cancer cell propagation stems from elevated levels of blood glucose, etc and the cancer cell's ability to influence signaling. The bottom line is that in the event that you have malignant cancerous cells in your body, having a high carb diet where those carbs are not used quickly as an energy source is probably going to help the cancerous cells grow and proliferate. No disagreement there.

 

I think we're both making the same point, but from different angles. You are stressing more of a ketogenic diet, whereas I'm stressing more activity.

 

The issue becomes comparing our diet to that of hunter-gatherer populations. The big difference between the two is how many calories are available and how many calories it takes to procure them. In a 'normal' diet for pretty much any animal, the name of the game is conserving energy, because there's an economy involved in getting calories...if its too much work, it's not worth the expenditure. Is it worth it for a predator to expend 500 calories to get a piece of food that contains 400 calories? No.

 

That's not a problem we face. We can walk to our freezer, expend 30 calories, and grab a Ben and Jerry's ice cream that has 1000 calories. So, we face an entirely different set of conditions in nourishing ourselves. We have more carbs available to us than those populations, at far less of a cost. At the end of the day, as we are both pointing out, we're taking in far more than we need.

 

For me, being extremely active, I don't do well on a ketogenic diet. I need a lot of energy quickly, and when I have tried to do things like reducing carbs, I simply run out of gas. But I don't have a lot of fat, so I don't have a bunch of energy stored to replace what I'm using. I constantly felt run down, and during strenuous exercise, I didn't have the endurance.

 

FitChick raises a good point that sort of ties it together. Many people have unhealthy diets and lifestyles and have more susceptibility to cancer as such, and once you are in a situation where you've got cancerous cells growing, continuing with the unhealthy diet and lifestyle is going to exacerbate the issue.