Tag Archives: cancer

Telomere length and the cancer-atherosclerosis trade-off 

Posted on July 10, 2016 | Comments Off on Telomere length and the cancer-atherosclerosis trade-off 

Telomeres are a hot research area now. If you can keep your telomeres long, you may live longer. But that may be an oversimplification. Click the link below for details. A teaser:

“Telomeres are caps of tandem repeats of DNA that protect the ends of all chromosomes. They are implicated in ageing because, with successive bouts of cell division, they are gradually whittled away to expose chromosomes to damage and, eventually, an inability to replicate any further. Sarah Tishkoff, together with co-authors Rivka Stone and Abraham Aviv, from the New Jersey Med School, and several others, have been taking a hard look at the evolution of telomere length across species and human groups and argue that there is a direct relationship between telomere length and susceptibility to cancer and atherosclerosis (and other diseases of ageing). Specifically, they describe evidence for an evolutionary trade-off whereby shorter telomeres in some human groups protect against cancer but expose individuals to a greater risk of other diseases in later life.”

Source: Telomere length and the cancer – atherosclerosis trade-off – The Evolution and Medicine Review

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R.I.P.: A Horse Named Steve; and a Neurosurgeon Confronts His Own Death

Posted on February 1, 2014 | 2 comments

The New York Times online has the story:

As soon as the CT scan was done, I began reviewing the images. The diagnosis was immediate: Masses matting the lungs and deforming the spine. Cancer. In my neurosurgical training, I had reviewed hundreds of scans for fellow doctors to see if surgery offered any hope. I’d scribble in the chart “Widely metastatic disease — no role for surgery,” and move on. But this scan was different: It was my own.

Well worth your time to read unless you’re in denial of death.

h/t Yoni Freedhoff.

*  *  *

A pall hangs over the Parker Compound since one of our horses died of colic yesterday. Certainly not the same as a human death, but still….  

My wife and daughter rescued Steve from appalling conditions  eight or nine years ago when he was about seven years old. They named him after me for some reason—his original name was Wyatt. Sunny paid $200 (USD) for Steve, which is one cheap horse. Many horses are like boats and airplanes in that they may not cost all the much initially—it’s the maintenance and repairs that get you.

The seller in Apache Junction, Arizona, had him in a large pen with 20 or 30 other horses. At feeding time, the owner threw a few flakes of hay into the pen and then it was “survival of the fittest” time. Horses are not by nature sharing creatures. Steve was not high up on the pecking order. If she hadn’t bought him, he may well have ended up in a meat market.

Steve was originally my daughter’s first horse, not mine. For reasons forgotten, we got her another horse, Buckwheat. Steve was to be my wife’s horse then. Soon enough Sunny broke her leg and was out of commission for months. Horses, like people, need exercise. The most fun way to exercise them is to ride them. That’s when I first started riding Steve, to give him exercise. My daughter and a cowgirl named Angel Antan were my instructors.

I had an odd experience with him one time when my daughter and I were on a trail ride to the Verde River from our home in Rio Verde. If you don’t know how to ride, note that a horse isn’t supposed to move or stop unless the rider gives the signal. You can’t let the horse be in charge. We were in a dry wash when Steve suddenly stopped and started sniffing the ground. I had no idea what was up and thought I’d just sit there waiting to see what would happen. Soon and without warning, Steve knelt down on his front legs, then his back ones, and was on his belly, starting to roll over! I jumped off and pulled him up by the reins before he did the deed. You do NOT want a horse rolling over on you, or your saddle for that matter. He never did that again, nor have I heard of that happening to others.

One of the cool things about our trail rides is that you can get close to coyotes. When you’re on horseback, the coyotes don’t perceive you as much of a threat.

Steve always liked men more than women. It was only in the last few months that my wife and he became quite fond of each other.

My wife gave him a great home. He was a good horse who taught me how to ride. I always felt safe when I was around him and on him, regardless of the near roll-over.

He “colicked” every year for the last five years. I’d like to think that Steve’s in horse heaven with his buddy Buckwheat, running over grassy  hills and wading through clear streams. RIP, Steve. No more pain, ever. 

Steve is the palomino on the right

Steve is the palomino on the right

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Why Are Nuts So Prominent in My Diet Plans?

Posted on November 26, 2013 | Comments Off on Why Are Nuts So Prominent in My Diet Plans?
Nuts with more omega-3 fatty acids (compared to omega-6) may be the healthiest

Nuts with the lowest omega-6/omega-3 fatty acid ratios may be the healthiest. In other words, increase your omega-3s and decrease omega-6s.

Conner Middelmann-Whitney explains in her recent post at Psychology Today. In a nutshell, they are linked to longer life and better health. For example:

In the largest study of its kind, Harvard scientists found that people who ate a handful of nuts every day were 20% less likely to die from any cause over a 30-year period than those who didn’t consume nuts. The study also found that regular nut-eaters were leaner than those who didn’t eat nuts, a finding that should calm any fears that eating nuts will make you gain weight.

The report also looked at the protective effect on specific causes of death. “The most obvious benefit was a reduction of 29% in deaths from heart disease—the major killer of people in America,” according to Charles S. Fuchs, director of the Gastrointestinal Cancer Treatment Center at Dana-Farber, the senior author of the report and a professor of medicine at Harvard Medical School. “But we also saw a significant reduction—11% —in the risk of dying from cancer,” added Fuchs.

Read the whole enchilada.

Nuts are integral to my Advanced Mediterranean Diet, Low-Carb Mediterranean Diet, Paleobetic Diet, and Ketogenic Mediterranean Diet.

Walnuts seem to have the lowest omega-6/omega-3 fatty acid ratio of all the common nuts. That may make them the healthiest nut. The jury is still out. Paleo dieters focus on cutting out omega-6s and increasing omega-3s. Julianne Taylor has a great post on how to do that with a variety of foods, not just nuts.

Steve Parker, M.D.

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Is mTORC1 Modulation the Key To Diseases of Civilization?

Posted on July 13, 2013 | Comments Off on Is mTORC1 Modulation the Key To Diseases of Civilization?

Was Hippocrates the dude that said something about “make food your medicine”?

Bodo Melnik has an article in DermatoEndocrinology regarding the dietary causes of acne.  He also comments on the role of Western foods in obesity, cancer, diabetes, high blood pressure, and neurodegenerative disorders.  These are our old friends, the “diseases of civilization.”  Melnik mentions the Paleolithic diet favorably.

Melnik says it’s all tied in with mTORC1: mammalian target of rapamycin complex 1.

A snippet:

These new insights into Western diet-mediated mTORC1-hyperactivity provide a rational basis for dietary intervention in acne by attenuating mTORC1 signaling by reducing (1) total energy intake, (2) hyperglycemic carbohydrates, (3) insulinotropic dairy proteins and (4) leucine-rich meat and dairy proteins. The necessary dietary changes are opposed to the evolution of industrialized food and fast food distribution of Westernized countries. An attenuation of mTORC1 signaling is only possible by increasing the consumption of vegetables and fruit, the major components of vegan or Paleolithic diets. The dermatologist bears a tremendous responsibility for his young acne patients who should be advised to modify their dietary habits in order to reduce activating stimuli of mTORC1, not only to improve acne but to prevent the harmful and expensive march to other mTORC1-related chronic diseases later in life.

You sciencey types can read the rest.  Our new friend mTOR also seems to be involved with growth of muscle induced by resistance exercise.

h/t Mangan

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Heart-Healthy Lifestyle Also Cuts Cancer Risk By Half

Posted on March 19, 2013 | 1 comment

…according to a report in MedPageToday.

I'm still not convinced that severe sodium restriction is necessary or even possible for most people

I’m still not convinced that severe sodium restriction is necessary or even possible for most people

The American Heart Association has published guidelines aiming to reduce premature death and illness caused by cardiovascular diseases such as heart attacks, high blood pressure, and strokes.

The guidelines focus on seven factors critical to cardiovascular health:

  • smoking
  • blood sugar
  • blood pressure
  • physical activity
  • total cholesterol
  • body mass index (BMI)
  • ideal diet

Using data from the Atherosclerosis Risk In Communities study (almost two decades’ follow-up), researchers found that those who maintained goals for six or seven of the American Heart Association critical factors had a 51% lower risk of cancer compared with those meeting no goals.

For detailed information about the specific goals, click here.

As you might expect, I was curious about what the American Heart Association considered a heart-healthy diet.  I quote the AHA summary:

The recommendation for the definition of the dietary goals and metric, therefore, is as follows: “In the context of a diet that is appropriate in energy balance, pursuing an overall dietary pattern that is consistent with a DASH [Dietary Approaches to Stop Hypertension]-type eating plan, including but not limited to:

  • Fruits and vegetables: ≥ 4.5 cups per day
  • Fish: ≥ two 3.5-oz servings per week (preferably oily fish)
  • Fiber-rich whole grains (≥ 1.1 g of fiber per 10 g of carbohydrate): ≥ three 1-oz-equivalent servings per day
  • Sodium: < 1500 mg per day
  • Sugar-sweetened beverages: ≤ 450 kcal (36 oz) per week

Intake goals are expressed for a 2000-kcal diet and should be scaled accordingly for other levels of caloric intake. For example, ≤ 450 calories per week represents only up to one quarter of discretionary calories (as recommended) coming from any types of sugar intake for a 2000-kcal diet.

Diet recommendations are more complicated than that; read the full report for details.  Only 5% of study participants ate the “ideal diet.”  The Mediterranean diet easily meets four out of five of those diet goals; you’d have to be extremely careful to reach the sodium goal on most any diet.

Cardiovascular diseases and cancer are among the top causes of death in Western societies.  Adhering to the guidelines above may kill two birds with one stone.

Steve Parker, M.D.

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Posted in Cancer, Coronary Heart Disease, Diet-Heart Hypothesis, Exercise, Heart Disease, High Blood Pressure

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Which Cancers Are Linked to Obesity?

Posted on January 13, 2013 | Comments Off on Which Cancers Are Linked to Obesity?

American Institute for Cancer Research has the list along with a helpful article.  You’d think that a person moving from obese down to overweight or normal weight would reduce future cancer risk, but I’m not sure that’s ever been proven.  We’ve learned in the last decade that obese and overweight patients with heart disease seem to live longer if they stay overweight – an example of the obesity paradox.

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Huge U.S. Study Confirms Health and Longevity Benefits of the Mediterranean Diet

Posted on September 3, 2012 | Comments Off on Huge U.S. Study Confirms Health and Longevity Benefits of the Mediterranean Diet

This is a reprint of the very first blog post I ever did, from December 24, 2007, at my old Advanced Mediterranean Diet Blog.  

We now have results of the first U.S. study on mortality and the Mediterranean dietary pattern.  380,000 people, aged 50-71, were surveyed on their dietary habits and scored on their conformity to the Mediterranean diet.  They were visited again 10 years later.  As you would expect, some of them died.  12,105 to be exact: 5985 from cancer, 3451 from cardiovascular disease, 2669 from other causes.  However, the people with the highest adherence to the Mediterranean diet had better survival overall, and specifically better odds of avoiding death from cardiovascular disease and cancer.  Compared to the people with low conformity to the Mediterranean diet, the high conformers were 15-20% less likely to die over the 10 years of the study.  The study authors, funded by the National Institutes of Health, noted eight similar studies in Europe and one in Australia with similar results.

Nothing to do with this post…I just like this picture

Once again, my promotion of the Mediterranean diet is vindicated by the scientific literature.  I’m not aware of any other diet that can prove anywhere near this degree of health benefit.  If you are, please share. 

Steve Parker, M.D.

Reference: Mitrou, Panagiota N., et al.  Mediterranean Dietary Pattern and Prediction of All-Cause Mortality in a US Population,  Archives of Internal Medicine, 167 (2007): 2461-2468.


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Mediterranean Diet Reduces Cancer Risk

Posted on July 7, 2012 | Comments Off on Mediterranean Diet Reduces Cancer Risk

In 2008, the British Journal of Cancer published a report linking the traditional Mediterranean diet “…with markedly and significantly reduced overall cancer….”

Researchers from the University of Athens, the International Agency for Research on Cancer, and the Harvard School of Public Health looked at 25,623 participants of the Greek portion of the European Prospective Investigation into Cancer and nutrition (the EPIC study).  Adherence to the Mediterranean diet was assessed with a food-frequency questionnaire.

Cancer developed in 851 participants over an average follow up of 7.9 years.  Non-melanoma skin cancers were not included since they are usually not serious or life-threatening.  The common cancers in men involved the lung, prostate, colon, and stomach.  For women, common cancers were breast, colon, ovary, and uterus.

Participants’ conformity to the Mediterranean diet was graded on a 10-point scale based on consumption of vegetables, legumes, fruits and nuts, cereals, fish, meat and meat products, dairy products, ethanol (alcohol), and the monounsaturated to saturated lipid ratio.  A score of zero indicated minimal adherence; maximal adherence scored a nine.

Every two-point increase in adherence was associated with a 12% reduction in the incidence of overall cancer.  So those participants with greatest conformity to the traditional Mediterranean diet had a dramatically reduced incidence of cancer compared to those with minimal adherence.

The researchers cite three independent studies that found a similar association between the Mediterranean diet and cancer.  The study at hand was not sufficiently powered to determine reliably which specific cancers were reduced with the Mediterranean diet.  Other studies indicate that the reduced cancers are prostate, breast, colon, and uterus.

The researchers surmise that the cancer-reducing benefit of the Mediterranean diet relates to the whole diet rather than to individual components.

To move your way of eating in a Mediterranean direction, review the diet here.

Steve Parker, M.D.

Reference:  Benetou, V., et al.  Conformity to traditional Mediterranean diet and cancer incidence: the Greek EPIC cohort.  British Journal of Cancer, 99 (2008): 191-195.

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Alcohol Consumption and Cancer in Women

Posted on May 30, 2012 | Comments Off on Alcohol Consumption and Cancer in Women

The Million Women Study (2009) looked at the association between alcohol consumption and the incidence of various cancers in middle-aged women in the United Kingdom.

Here’s the conclusion from the abstract in the Journal of the National Cancer Institute:

Low to moderate alcohol consumption in women increases the risk of certain cancers. For every additional drink regularly consumed per day, the increase in incidence up to age 75 years per 1000 for women in developed countries is estimated to be about 11 for breast cancer, 1 for cancers of the oral cavity and pharynx, 1 for cancer of the rectum, and 0.7 each for cancers of the esophagus, larynx and liver, giving a total excess of about15 cancers per 1000 women up to age 75.

Other cancers seemed to be reduced by increasing levels of alcohol consumption: thyroid, non-Hodgkin lymphoma, renal cell carcinoma.

Comparing wine with other alcohol types, no differences in cancer risks were found.

Low to moderate alcohol consumption is associated with prolonged life, lesser risk of dementia, and lower rates of cardiovascular disease. The article abstract doesn’t mention these issues, nor the possibility that the benefits of judicious alcohol consumption may outweigh the cancer risks. 

Steve Parker, M.D.

References:

Allen, Naomi, et al. Moderate Alcohol Intake and Cancer Incidence in Women. Journal of the National Cancer Institute, 101 (2009): 296-305.

Lauer, Michael and Sorlie, Paul. Alcohol, Cardiovascular Disease, and Cancer: Treat With Caution. Journal of the National Cancer Institute, 101 (2009): 282-283.

Szwarc, Sandy. In Vino Veritas – Part Two. Junkfood Science blog, March 1, 2009. Accessed March 10, 2009. A quote from Ms. Szwarc regarding the Million Women Study:

The bottom line is that scary claims that “there is no level of alcohol consumption that can be considered safe,” simply was not supported by the data. This study actually found no credible link between alcohol consumption and cancers at all. Or, if you want to split hairs and believe the small computed numbers, it found that the lowest risk for cancers was associated with women drinking up to 1-2 drinks a day.

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Glycemic Index and Chronic Disease Risk (Mostly in Women)

Posted on May 26, 2012 | 3 comments

I’ve written about glycemic index (GI), glycemic load (GL), and glycemic diets in preparation for today’s post.

The concept of glycemic index was introduced by Jenkins et al in 1981 at the University of Toronto.

Studies investigating the association between disease risk and GI/GL have been inconsistent. By “inconsistent,” I mean some studies have made an association in one direction or the other, and other studies have not. Diseases possibly associated with high-glycemic diets have included diabetes, cardiovascular disease, cancer, gallbladder disease, and eye disease.

“Diet” in this post refers to a habitual way of eating, not a weight loss program.

Researchers with the University of Sydney (Sydney, Australia) identified the best-designed published research reports investigating the relationship between certain chronic diseases and glycemic index and load. The studied diseases were type 2 diabetes, coronary heart disease, stroke, breast cancer, colorectal cancer, pancreatic cancer, endometrial cancer, ovarian cancer, gallbladder disease, and eye disease.

Methodology

Literature databases were searched for articles published between 1981 and March, 2007. The researchers found 37 studies that enrolled 1,950,198 participants ranging in age from 24 to 76, with BMI’s averaging 23.5 to 29. These were human prospective cohort studies with a final outcome being occurrence of a chronic disease (not its risk factors). Twenty-five of the studies were conducted in the U.S., five in Canada, five Europe, and two in Australia. Ninety percent of participants were women [for reasons not discussed]. Food frequency questionnaires were used in nearly all the studies. Individual studies generated between 4 to 20 years of follow-up, and 40,129 new cases of target diseases were identified.

Associations between GI, GL, and risk of developing a chronic disease were measured as rate ratios comparing the highest with the lowest quantiles. For example, GI and GL were measured in the study population. The population was then divided into four groups (quartiles), reflecting lowest GI/GL to medium to highest GI/GL diets. The lowest GI/GL quartile was compared with the highest quartile to see if disease occurrence was different between the groups. Some studies broke the populations into tertiles, quintiles, deciles, etc.

Findings

Comparing the highest with the lowest quantiles, studies with a high GI or GL independently

  • increased the risk of type 2 diabetes by 27 (GL) or 40% (GI)
  • increased the risk of coronary heart disease by 25% (GI)
  • increased the risk of gallbladder disease by 26% (GI) or 41% (GL) (gallstones and biliary colic, I assume, but the authors don’t specify)
  • increased the risk of breast cancer by 8% (GI)
  • increased risk of all studied diseases (11) combined by 14% (GI) or 9% (GL)

Overall, high GI was more strongly associated with chronic disease than was high GL

So low-GI diets may offer greater protection against disease than low-GL diets.

Comments from the Researchers

They speculate that low-GI diets may be more protective than low-GL because the latter can include low-carb foods such as cheese and meat, and low-GI, high-carb foods. Both eating styles will reduce glucose levels after meals while having very different effects in other areas such as pancreas beta cell function, free fatty acid levels, triglyceride levels, and effects on satiety.

High GI and high GL diets, independently of known confounders, modestly increase the risk of chronic lifestyle-related diseases, with more pronounced effects for type 2 diabetes, coronary heart disease, and gallbladder disease.

Direct quotes:

. . . 90% of participants were female; therefore, the findings may not be generalizable to men.

There are plausible mechanism linking the development of certain chronic diseases with high-GI diets. Specifically, 2 major pathways have been proposed to explain the association with type 2 diabetes risk. First the same amount of carbohydrate from high-GI food produces higher blood glucose concentrations and a greater demand for insulin. The chronically increased insulin demand may eventually result in pancreatic beta cell failure, and, as a consequence, impaired glucose tolerance. Second, there is evidence that high-GI diets may directly increase insulin resistance through their effect on glycemia, free fatty acids, and counter-regulatory hormone secretion. High glucose and insulin concentrations are associated with increased risk profiles for cardiovascular disease, including decreased concentrations of HDL cholesterol, increased glycosylated protein, oxidative status, hemostatic variables, and poor endothelial function

Low-GI and/or low-GL diets are independently associated with a reduced risk of certain chronic diseases. In diabetes and heart disease, the protection is comparable with that seen for whole grain and high fiber intakes. The findings support the hypothesis that higher postprandial glycemia is a universal mechanism for disease progression.

My Comments

Studies like this tend to accentuate the differences in eating styles since they compare the highest with the lowest post-prandial (after meal) glucose levels. Most people are closer to the middle of the pack, so a person there has potentially less to gain by moving to a low-GI diet. But still some to gain, on average, particularly in regards to avoiding type 2 diabetes and coronary heart disease.

(To be fair, many population-based studies use this same quantile technique. It increases the odds of finding a statistically significant difference.)

Only two of the 37 studies examined coronary heart disease, the cause of heart attacks. One study was the massive Nurses’ Health Study database with 75,521 women. The other was the Zutphen (Netherlands) Elderly Study which examined men 64 and older. Here’s the primary conclusion of the Zutphen authors verbatim:

Our findings do not support the hypothesis that a high-glycemic index diet unfavorably affects metabolic risk factors or increases risk for CHD [coronary heart disease] in elderly men without a history of diabetes or CHD.

So there’s nothing in the meta-analysis at hand to suggest that high-GI/GL diets promote heart disease in males in the general population.

However, the recent Canadian study in Archives of Internal Medicine found strong evidence linking CHD with high-glycemic index diets. Although not mentioned in the text of that article, Table 3 on page 664 shows that the association is much stonger in women than in men. Relative risk for women on a high-glycemic index/load diet was 1.5 (95% confidence interval = 1.29-1.71), and for men the relative risk was 1.06 (95% confidence interval = 0.91-1.20). See reference below.

Nine of the 37 studies examined the occurrence of type 2 diabetes. Only one of these studied men only – 42,759 men: the abstract is not available online and the Sydney group does not mention if high-GI or high-GL was positively associated with onset of diabetes in this cohort. Two of the diabetes studies included both men and women, but the abstracts don’t break down the findings by sex. (I’m trying to deduce if the major overall findings of this meta-analysis apply to men or not.)

I don’t know anybody willing to change their diet just to avoid the risk of gallstones. It’s only after they develop symptomatic gallstones that they ask me what they can do about them. The usual answer is surgery.

The report is well-done and seems free of commercial bias, even though several of the researchers are authors or co-authors of popular books on low-GI eating.

Steve Parker, M.D.

References:

Barclay, Alan W.; Petocz, Peter; McMillan-Price, Joanna; Flood, Victoria M.; Prvan, Tania; Mitchell, Paul; and Brand-Miller, Jennie C. Glycemic index, glycemic load, and chronic disease risk – a meta-analysis of observational studies [of mostly women]. American Journal of Clinical Nutrition, 87 (2008): 627-637.

Brand-Miller, Jennie, et al. “The New Glucose Revolution: The Authoritative Guide to the Glycemic Index – The Dietary Solution for Lifelong Health.” Da Capo Press, 2006.

Mente, Andrew, et al. A Systematic Review of the Evidence Supporting a Causal Link Between Dietary Factors and Coronary Heart Disease. Archives of Internal Medicine, 169 (2009): 659-669.

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