Colon Cancer Prevention and Anti-Inflammatory Diets

Written by Dr. Steve Chaney on . Posted in Colon Cancer

How Can You Reduce Colon Cancer Risk?

Author: Dr. Stephen Chaney

 

colon cancer prevention colorectalColorectal cancer is third most common form of cancer in the United States. The American Cancer Society estimates that there will be 140,000 new cases and 50,000 deaths from colorectal cancer in 2018. The death rate has been decreasing due to more aggressive screening, but it is still much too high.

Thus, there is considerable interest in discovering colon cancer prevention we can control. Several studies have suggested that inflammatory diets may be one preventable cause of colon cancer. There are many reasons for suspecting that inflammation may increase colon cancer risk. For example, we know:

  • Inflammation plays an important mechanistic role in cancer development.
  • Obesity causes a chronic state of low-grade inflammation, and obesity increases colon cancer risk.
  • Inflammatory bowel disease increases the risk of colon cancer.
  • Anti-inflammatory medications such as aspirin decrease colon cancer risk.

However, it has been difficult to prove that inflammatory diets increase colon cancer risk. In part, that is because we can’t measure inflammation directly. We must rely on inflammatory markers such as C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor (TNF). Unfortunately, these markers correlate with different inflammatory processes in the body and seldom increase or decrease in unison.

The authors of the current study (FK Tabung et al, JAMA Oncology, 4: 366-373, 2018 ) used a dietary scoring system based on all three inflammatory markers to examine the correlation between an inflammatory diet and colon cancer risk.

How Was The Study Done?

colon cancer prevention inflammationThis study made use of data collected from 46,804 men enrolled in the Health Professionals Follow-up Study (conducted between 1986 and 2012) and 74,246 women enrolled in the Nurses’ Health Study (conducted between 1984 and 2012). Lifestyle, medical, and other health-related information were collected every 2 years. A comprehensive dietary questionnaire was administered every 4 years. During the 26-year follow-up period 2699 cases of colon cancer were diagnosed.

The inflammatory potential of the diet was estimated using an index called the empirical dietary inflammation pattern (EDIP) score that the authors had developed in a previous study (FK Tabung et al, Journal of Nutrition, 146: 1560-1570, 2016 ). This index was based on the effects of individual foods on all three markers of inflammation (CRP, IL-6, and TNF). Inflammatory foods had positive EDIP scores (they increased levels of one or more of the inflammatory markers). Anti-inflammatory foods had negative EDIP scores (they decreased levels of one or more inflammatory markers).

Most of the EDIP scores were consistent with previous studies on the inflammatory potential of various foods. For example:

  • Red meats, processed meats, refined grains, sugar-sweetened beverages, and diet beverages all scored as highly inflammatory.
  • One serving of beer or wine, coffee, dark yellow vegetables, and leafy green vegetables all scored as highly anti-inflammatory.

 

Colon Cancer Prevention By Avoiding Inflammatory Diets

colon cancer prevention fireThe subjects enrolled in the study were divided into five groups based on their inflammatory diet (EDIP) scores. When the investigators compared subjects who had the most inflammatory diet with subjects who had the least inflammatory diet:

  • The risk of colon cancer was increased by 44% in men and 22% in women.
  • People who refrain from alcohol consumption received even greater benefit from anti-inflammatory diets. For teetotalers an anti-inflammatory diet decreased colon cancer risk by 62% in men and 33% in women.

The authors concluded: “Findings from this large prospective [that is scientific jargon meaning the study was carried out over a period of many years] study support a role for the inflammatory potential of diet in colorectal cancer development, suggesting inflammation as a potential mechanism linking dietary patterns and colorectal cancer development.”

 

How To Prevent Colon Cancer Or At Lest Reduce The Risk?

 

colon cancer prevention american cancer societyOf course, holistic approaches are always best. Reducing colon cancer risk involves much more than simply consuming an anti-inflammatory diet. To put this study in perspective, let’s look at what the American Cancer Society recommendations about modifiable lifestyle factors that increase your risk of colon cancer. So, consider these when you think about colon cancer prevention.  I call this the 10,000-foot view because they only list the biggest contributors to colon cancer – the ones for which there is the most scientific evidence (I have put their exact comments in quotes):

#1: Being overweight or obese. “If you are overweight or obese your risk of developing and dying from colorectal cancer is higher”.

#2: Physical inactivity. “If you are not physically active, you have a greater chance of developing colon cancer.”

#3: Certain types of diets.

  • “A diet that’s high in red meats (such as beef, pork, lamb, or liver) and processed meats (like bacon, sausage, hot dogs and some luncheon meats) raises your colorectal cancer risk.” My comment: The evidence is stronger for red meats and processed meats than for any other foods. Processed meats are listed as likely carcinogens and red meats are listed as probable carcinogens by the International Agency For Research On Cancer (IARC), an agency of the WHO.
  • “Cooking meats at very high temperatures (frying, broiling, or grilling) creates chemicals that may raise your cancer risk.”

#4: Smoking. “People who have smoked for a long time are more likely than non-smokers to develop and die from colorectal cancer.”

#5: Heavy alcohol use. “Colorectal cancer has been linked to moderate to heavy alcohol use. Limiting alcohol use to no more than 2 drinks a day for men and 1 drink a day for women could have many health benefits, including a lower risk of many kinds of cancer. “

#6: Early detection. In case you have not heard, the American Cancer Society just released new guidelines recommending that screening for colon cancer begin at age 45.

If you want to take a closer look at the diet – colon cancer connection, you might be interested in the recommendations of Harvard’s Men’s Health Watch newsletter.

 

What Does This Mean For You?

colon cancer prevention inflammatory dietsIf you are confused about the conflicting information about which foods affect colon cancer risk, start with the American Cancer Society recommendations. Avoid red meats and processed meats as much as possible and don’t cook your meats at high temperatures. I realize this is not popular advice at the time of year when everyone is firing up their grills for summer cookouts, but these recommendations will go a long way towards colon cancer prevention. Don’t shoot the messenger. I’m just conveying information based on the best scientific evidence we have to date.

For best results follow the recommendations of the Harvard Men’s Health Watch newsletter to also avoid fried foods, sugary beverages and refined carbohydrates and add anti-inflammatory foods such as fresh fruits & vegetables, nuts, olive oil, and fatty fish.

With Harvard’s recommendations in mind, let me extend an olive branch to all of you red meat lovers. An ounce or two of red meat in a green salad or a stir fry with lots of fresh, colorful vegetables is much less likely to increase your risk of cancer than a steak or burger with fries. You will find more information on this topic in my book “Slaying The Food Myths.”

 

The Bottom Line:

A major study has just been published looking at the correlation between an inflammatory diet and colon cancer risk. When the investigators compared subjects who had the most inflammatory diet with subjects who had the least inflammatory diet:

  • The risk of colon cancer was increased by 44% in men and 22% in women.
  • People who refrain from alcohol consumption received even greater benefit from anti-inflammatory diets. For teetotalers an anti-inflammatory diet decreased colon cancer risk by 62% in men and 33% in women.

The authors concluded: “Findings from this large study support a role for the inflammatory potential of diet in colorectal cancer development, suggesting inflammation as a potential mechanism linking dietary patterns and colorectal cancer development.”

If you are confused about the conflicting information about which foods are inflammatory and anti-inflammatory, start with the American Cancer Society recommendations. Avoid red meats and processed meats as much as possible and don’t cook your meats at high temperatures. I realize this is not popular advice at the time of year that everyone is firing up their grills for summer cookouts, but these recommendations will go a long way towards colon cancer prevention.

For best results follow the recommendations of the Harvard Men’s Health Watch newsletter to also avoid inflammatory foods such as fried foods, sugary beverages and refined grains and add anti-inflammatory foods such as fresh fruits & vegetables, nuts, olive oil, and fatty fish.

With Harvard’s recommendations in mind, let me extend an olive branch to all of you red meat lovers. An ounce or two of red meats in a green salad or a stir fry with lots of fresh, colorful fruits and vegetables is much less likely to increase your risk of cancer than a steak or burger with fries. You will find more information on this topic in my book “Slaying The Food Myths.”

For more details on the American Cancer Society and Harvard recommendations and colon cancer prevention, read the article above:

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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Latest Article

A Low Carb Diet and Weight Loss

Posted January 15, 2019 by Dr. Steve Chaney

Do Low-Carb Diets Help Maintain Weight Loss?

Author: Dr. Stephen Chaney

 

low carb dietTraditional diets have been based on counting calories, but are all calories equal? Low-carb enthusiasts have long claimed that diets high in sugar and refined carbs cause obesity. Their hypothesis is based on the fact that high blood sugar levels cause a spike in insulin levels, and insulin promotes fat storage.

The problem is that there has been scant evidence to support that hypothesis. In fact, a recent meta-analysis of 32 published clinical studies (KD Hall and J Guo, Gastroenterology, 152: 1718-1727, 2017 ) concluded that low-fat diets resulted in a higher metabolic rate and greater fat loss than isocaloric low-carbohydrate diets.

However, low-carb enthusiasts persisted. They argued that the studies included in the meta-analysis were too short to adequately measure the metabolic effects of a low-carb diet. Recently, a study has been published in the British Medical Journal (CB Ebbeling et al, BMJ 2018, 363:k4583 ) that appears to vindicate their position.

Are low carb diets best for long term weight loss?

Low-carb enthusiasts claim the study conclusively shows that low-carb diets are best for losing weight and for keeping it off once you have lost it. They are saying that it is time to shift away from counting calories and from promoting low-fat diets and focus on low-carb diets instead if we wish to solve the obesity epidemic. In this article I will focus on three issues:

  • How good was the study?
  • What were its limitations?
  • Are the claims justified?

 

How Was The Study Designed?

low carb diet studyThe investigators started with 234 overweight adults (30% male, 78% white, average age 40, BMI 32) recruited from the campus of Framingham State University in Massachusetts. All participants were put on a diet that restricted calories to 60% of estimated needs for 10 weeks. The diet consisted of 45% of calories from carbohydrate, 30% from fat, and 25% from protein. [So much for the claim that the study showed low-carb diets were more effective for weight loss. The diet used for the weight loss portion of the diet was not low-carb.]

During the initial phase of the study 161 of the participants achieved 10% weight loss. These participants were randomly divided into 3 groups for the weight maintenance phase of the study.

  • The diet composition of the high-carb group was 60% carbohydrate, 20% fat, and 20% protein.
  • The diet composition of the moderate-carb group was 40% carbohydrate, 40% fat, and 20% protein.
  • The diet composition of the low-carb group was 20% carbohydrate, 60% fat, and 20% protein.

Other important characteristics of the study were:

  • The weight maintenance portion of the study lasted 5 months – much longer than any previous study.
  • All meals were designed by dietitians and prepared by a commercial food service. The meals were either served in a cafeteria or packaged to be taken home by the participants.
  • The caloric content of the meals was individually adjusted on a weekly basis so that weight was kept within a ± 4-pound range during the 5-month maintenance phase.
  • Sugar, saturated fat, and sodium were limited and kept relatively constant among the 3 diets.

120 participants made it through the 5-month maintenance phase.

 

Do Low-Carb Diets Help Maintain Weight Loss?

low carb diet maintain weight lossThe results were striking:

  • The low-carb group burned an additional 278 calories/day compared to the high-carb group and 131 calories/day more than the moderate-carbohydrate group.
  • These differences were even higher for those individuals with higher insulin secretion at the beginning of the maintenance phase of the study.
  • These differences lead the authors to hypothesize that low-carb diets might be more effective for weight maintenance than other diets.

 

What Are The Pros And Cons Of This Study?

low carb diet pros and consThis was a very well-done study. In fact, it is the most ambitious and well-controlled study of its kind. However, like any other clinical study, it has its limitations. It also needs to be repeated.

The pros of the study are obvious. It was a long study and the dietary intake of the participants was tightly controlled.

As for cons, here are the three limitations of the study listed by the authors:

#1: Potential Measurement Error: This section of the paper was a highly technical consideration of the method used to measure energy expenditure. Suffice it to say that the method they used to measure calories burned per day may overestimate calories burned in the low-carb group. That, of course, would invalidate the major findings of the study. It is unlikely, but it is why the study needs to be repeated using a different measure of energy expenditure.

#2: Compliance: Although the participants were provided with all their meals, there was no way of being sure they ate them. There was also no way of knowing whether they may have eaten other foods in addition to the food they were provided. Again, this is unlikely, but cannot be eliminated from consideration.

#3: Generalizability: This is simply an acknowledgement that the greatest strength of this study is also its greatest weakness. The authors acknowledged that their study was conducted in such a tightly controlled manner it is difficult to translate their findings to the real world. For example:

  • Sugar and saturated fat were restricted and were at very similar levels in all 3 diets. In the real world, people consuming a high-carb diet are likely to consume more sugar than people in the other diet groups. Similarly, people consuming the low-carb diet are likely to consume more saturated fat than people in the other diet groups.
  • Weight was kept constant in the weight maintenance phase by constantly adjusting caloric intake. Unfortunately, this seldom happens in the real world. Most people gain weight once they go off their diet – and this is just as true with low-carb diets as with other diets.
  • The participants had access to dietitian-designed prepared meals 3 times a day for 5 months. This almost never happens in the real world. The authors said “…these results [their data] must be reconciled with the long-term weight loss trials relying on nutrition education and behavioral counseling that find only a small advantage for low carbohydrate compared with low fat diets according to several recent meta-analyses.” [I would add that in the real world, people do not even have access to nutritional education and behavioral modification.]

 

low carb diet and youWhat Does This Study Mean For You?

  • This study shows that under very tightly controlled conditions (dietitian-prepared meals, sugar and saturated fat limited to healthy levels, calories continually adjusted so that weight remains constant) a low-carb diet burns more calories per day than a moderate-carb or high-carb diet. These findings show that it is theoretically possible to increase your metabolic weight and successfully maintain a healthy weight on a low-carb diet. These are the headlines you probably saw. However, a careful reading of the study provides a much more nuanced viewpoint. For example, the fact that the study conditions were so tightly controlled makes it difficult to translate these findings to the real world.
  • In fact, the authors of the study acknowledged that multiple clinical studies show this almost never happens in the real world. These studies show that most people regain the weight they have lost on low-carb diets. More importantly, the rate of weight regain is virtually identical on low-carb and low-fat diets. Consequently, the authors of the current study concluded “…translation [of their results to the real world] requires exploration in future mechanistic oriented research.” Simply put, the authors are saying that more research is needed to provide a mechanistic explanation for this discrepancy before one can make recommendations that are relevant to weight loss and weight maintenance in the real world.
  • The authors also discussed the results of their study in light of a recent, well-designed 12-month study (CD Gardener et al, JAMA, 319: 667-669, 2018 ) that showed no difference in weight change between a healthy low-fat versus a healthy low-carbohydrate diet. That study also reported that the results were unaffected by insulin secretion at baseline. The authors of the current study noted that “…[in the previous study] participants were instructed to minimize or eliminate refined grains and added sugars and maximize intake of vegetables. Probably for this reason, the reported glycemic load [effect of the diet on blood sugar levels] of the low-fat diet was very low…and similar to [the low-carb diet].” In short, the authors of the current study were acknowledging that diets which focus on healthy, plant-based carbohydrates and eliminate sugar, refined grains, and processed foods may be as effective as low-carb diets for helping maintain a healthy weight.
  • This would also be consistent with previous studies showing that primarily plant-based, low-carb diets are more effective at maintaining a healthy weight and better health outcomes long-term than the typical American version of the low-fat diet, which is high in sugar and refined grains. In contrast, meat-based, low-carb diets are no more effective than the American version of the low-fat diet at preventing weight gain and poor health outcomes. I have covered these studies in detail in my book “Slaying The Food Myths.”

Consequently, the lead author of the most recent study has said: “The findings [of this study] do not impugn whole fruits, beans and other unprocessed carbohydrates. Rather, the study suggests that reducing foods with added sugar, flour, and other refined carbohydrates could help people maintain weight loss….” This is something we all can agree on, but strangely this is not reflected in the headlines you may have seen in the media.

The Bottom Line

 

  • A recent study compared the calories burned per day on a low-carb, moderate-carb, and high-carb diet. The study concluded that the low-carb diet burned significantly more calories per day than the other two diets and might be suitable for long-term weight control. If confirmed by subsequent studies, this would be the first real evidence that low-carb diets are superior for maintaining a healthy weight.
  • However, the study has some major limitations. For example, it used a methodology that may overestimate the benefits of a low-carb diet, and it was performed under tightly controlled conditions that can never be duplicated in the real world. As acknowledged by the authors, this study is also contradicted by multiple previous studies. Further studies will be required to confirm the results of this study and show how it can be applied in the real world.
  • In addition, the kind of carbohydrate in the diet is every bit as important as the amount of carbohydrate. The authors acknowledge that the differences seen in their study apply mainly to carbohydrates from sugar, refined grains, and processed foods. They advocate diets with low glycemic load (small effects on blood sugar and insulin levels) and acknowledge this can also be achieved by incorporating low-glycemic load, plant-based carbohydrates into your diet. This is something we all can agree on, but strangely this is not reflected in the headlines you may have seen in the media.
  • Finally, clinical studies report averages, but none of us are average. When you examine the data from the current study, it is evident that some participants burned more calories per hour on the high-carb diet than other participants did on the low carb diet. That reinforces the observation that some people lose weight more effectively on low-carb diets while others lose weight more effectively on low-fat diets. If you are someone who does better on a low-carb diet, the best available evidence suggests you will have better long-term health outcomes on a primarily plant-based, low-carb diet such as the low-carb version of the Mediterranean diet.

For more details read the article above.

 

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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