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This study found that people with high red meat intake, combined with low fruit and vegetable intake and a poor overall diet (which was found most frequently in males of low socioeconomic status) had biological markers indicating accelerated aging and poor renal function (early indicators of chronic kidney disease). Bottom line: eat less red meat, more whole grains, more fruits and vegetables for your health. From Medical Xpress:

Too much red meat and too few vegetables may increase your body's biological age

A diet containing too much red meat and not enough fruit and vegetables could increase your body's 'biological age' and contribute to health problems. Research led by the University of Glasgow and published today in Aging, has found that a moderate increase in serum phosphate levels caused by red meat consumption, combined with a poor overall diet, increases biological age (miles on the clock) in contrast to chronological age (years of age).
The study, which looked at participants from the most deprived to the least deprived in the NHS Greater Glasgow Health Board area, also demonstrates that deprived males were the worst affected.

Data from the study suggests that accelerated biological ageing, and dietary derived phosphate levels among the most deprived males, were directly related to the frequency of red meat consumption. Researchers believe that excess red meat particularly affects this group because of their poor diet and "sub-optimal fruit and vegetable intake".
The research, led by the Institute of Cancer Sciences in collaboration with the Karolinska Institutet (Stockholm, Sweden), also found that high phosphate levels in deprived males correlated with reduced kidney function and even underlying mild to moderate chronic kidney disease.

Phosphate is naturally present in basic foodstuffs, including meats, fish, eggs, dairy products and vegetables. Intestinal absorption of naturally occurring phosphate is minimally regulated, as absorption is efficient, hence high supplementation results in markedly elevated levels of serum phosphate, which can have adverse health consequences. Indeed high phosphate levels, as a consequence of dietary intake, have already been linked to higher all-cause and cardiovascular mortality risk, premature vascular ageing and kidney disease.

The researchers observed significant relationships between serum phosphate and biological age markers, including DNA content and telomere length(Original study.)

Another study showing big problems with anticholinergics, which are in many popular medicines - both non-prescription and prescription (e.g., Chlor-Trimeton, Benadryl, Tavist, Dimetapp). An earlier study with older adults found a dose-response link with dementia, but the current study explored this issue further. They followed 2 groups of  "cognitively normal older adults" in their early 70s for several years: those who took anticholinergic medicines and those who did not take anticholinergic medicines. They found that those who took anticholinergic medicines had reduced brain volume (brain shrinking) and cognitive decline (when compared to those who did not take anticholinergic medicines). The researchers summarized their findings as the "use of anticholinergic medication was associated with increased brain atrophy and dysfunction and clinical decline". This finding was greatest for those taking drugs with the most anticholinergic activity.

See a list of anticholinergic medicines  from the Aging Brain Program of the Indiana University Center for Aging Research. Definitely try to avoid medicines with a score of 2 (medium effect) or 3 (high effect), but I would even be cautious about score 1 (low effect) medicines - use all medicines only as long as absolutely needed. My one very important question is: If these effects are found in older adults, what do anticholinergics do to younger brains, especially the developing brains of children? From Medical Xpress:

Brain scans link physical changes to cognitive risks of widely used class of drugs

Older adults might want to avoid a using class of drugs commonly used in over-the-counter products such as nighttime cold medicines due to their links to cognitive impairment, a research team led by scientists at Indiana University School of Medicine has recommended. Using brain imaging techniques, the researchers found lower metabolism and reduced brain sizes among study participants taking the drugs known to have an anticholinergic effect, meaning they block acetylcholine, a nervous system neurotransmitter.

Previous research found a link between between the anticholinergic drugs and cognitive impairment and increased risk of dementia.....Drugs with anticholinergic effects are sold over the counter and by prescription as sleep aids and for many chronic diseases including hypertension, cardiovascular disease, and chronic obstructive pulmonary disease. A list of anticholinergic drugs and their potential impact is at http://www.agingbraincare.org/uploads/products/ACB_scale_-_legal_size.pdf.

Scientists have linked anticholinergic drugs and cognitive problems among older adults for at least 10 years. A 2013 study by scientists at the IU Center for Aging Research and the Regenstrief Institute found that drugs with a strong anticholinergic effect cause cognitive problems when taken continuously for as few as 60 days. Drugs with a weaker effect could cause impairment within 90 days.

The current research project involved 451 participants, 60 of whom were taking at least one medication with medium or high anticholinergic activity. The participants were drawn from a national Alzheimer's research project....and the Indiana Memory and Aging Study. To identify possible physical and physiological changes that could be associated with the reported effects, researchers assessed the results of memory and other cognitive tests, positron emission tests (PET) measuring brain metabolism, and magnetic resonance imaging (MRI) scans for brain structure.

The cognitive tests revealed that patients taking anticholinergic drugs performed worse than older adults not taking the drugs on short-term memory and some tests of executive function, which cover a range of activities such as verbal reasoning, planning, and problem solving. Anticholinergic drug users also showed lower levels of glucose metabolism—a biomarker for brain activity—in both the overall brain and in the hippocampus, a region of the brain associated with memory and which has been identified as affected early by Alzheimer's disease. The researchers also found significant links between brain structure revealed by the MRI scans and anticholinergic drug use, with the participants using anticholinergic drugs having reduced brain volume and larger ventricles, the cavities inside the brain.

Another study showing that higher physical activity (from a variety of activities) is "related to larger gray matter volume in the elderly, regardless of cognitive status", specifically in gray matter areas of the brain responsible for memory, learning, and cognition. In other words, higher levels of physical activity reduce brain atrophy that occurs with aging and improves cognitive function in elderly individuals.  There is also discussion of higher activity levels improving cerebral (brain) blood flow. Bottom line: get off your butt and move more for better brain health. From Medical Xpress:

Burning more calories linked with greater gray matter volume, reduced Alzheimer's risk

Whether they jog, swim, garden or dance, physically active older persons have larger gray matter volume in key brain areas responsible for memory and cognition, according to a new study by researchers at the University of Pittsburgh School of Medicine and UCLA.The findings, published today in the Journal of Alzheimer's Disease, showed also that people who had Alzheimer's disease or mild cognitive impairment experienced less gray matter volume reduction over time if their exercise-associated calorie burn was high.

A growing number of studies indicate physical activity can help protect the brain from cognitive decline, said investigator James T. Becker, Ph.D., professor of psychiatry, Pitt School of Medicine..... "Our study is one of the largest to examine the relationship between physical activity and cognitive decline, and the results strongly support the notion that staying active maintains brain health."

Led by Cyrus Raji, M.D., Ph.D., formerly a student at Pitt School of Medicine and now a senior radiology resident at UCLA, the team examined data obtained over five years from nearly 876 people 65 or older participating in the multicenter Cardiovascular Health Study. All participants had brain scans and periodic cognitive assessments. They also were surveyed about how frequently they engaged in physical activities, such as walking, tennis, dancing and golfing, to assess their calorie expenditure or energy output per week.

Using mathematical modeling, the researchers found that the individuals who burned the most calories had larger gray matter volumes in the frontal, temporal and parietal lobes of the brain, areas that are associated with memory, learning and performing complex cognitive tasks. In a subset of more than 300 participants at the Pitt site, those with the highest energy expenditure had larger gray matter volumes in key areas on initial brain scans and were half as likely to have developed Alzheimer's disease five years later.

"Gray matter houses all of the neurons in your brain, so its volume can reflect neuronal health," Dr. Raji explained. "We also noted that these volumes increased if people became more active over five years leading up to their brain MRI."

 Two articles about the link between Alzheimer's disease (AD) and microbes this past week: a study linking periodontal disease and Alzheimer's, and the other a journal editorial (written by an international team of 31 researchers) suggesting that we need to more closely look at the role of microbes in Alzheimer's disease, especially herpes virus, chlamydia and spirochaete bacteria.

This team is suggesting an "infectious cause" for Alzheimer's, an example being the reactivation of herpes simplex virus type 1 (HSV1) in the person. The researchers state that "regarding HSV1, about 100 publications by many groups indicate directly or indirectly that this virus is a major factor in the disease".  The team also mentions the possibility of fungi infection in some cases (see my November 6, 2015 post about a study finding fungal involvement). Both articles mention that treatment of the diseases with some form of antimicrobials or antivirals could possibly treat Alzheimer's disease, and that trails now need to be done.

From Science Daily: Link between gum disease and cognitive decline in Alzheimer’s

A new study has found a link between gum disease and greater rates of cognitive decline in people with early stages of Alzheimer's Disease. Periodontitis or gum disease is common in older people and may become more common in Alzheimer's disease because of a reduced ability to take care of oral hygiene as the disease progresses. Higher levels of antibodies to periodontal bacteria are associated with an increase in levels of inflammatory molecules elsewhere in the body, which in turn has been linked to greater rates of cognitive decline in Alzheimer's disease in previous studies.

The presence of gum disease at baseline was associated with a six-fold increase in the rate of cognitive decline in participants over the six-month follow-up period of the study. Periodontitis at baseline was also associated with a relative increase in the pro-inflammatory state over the six-month follow-up period. The authors conclude that gum disease is associated with an increase in cognitive decline in Alzheimer's Disease, possibly via mechanisms linked to the body's inflammatory response.....However, growing evidence from a number of studies links the body's inflammatory response to increased rates of cognitive decline, suggesting that it would be worth exploring whether the treatment of gum disease might also benefit the treatment of dementia and Alzheimer's Disease.

From Journal of Alzheimer's Disease: Microbes and Alzheimer’s Disease

We are researchers and clinicians working on Alzheimer’s disease (AD) or related topics, and we write to express our concern that one particular aspect of the disease has been neglected, even though treatment based on it might slow or arrest AD progression. We refer to the many studies, mainly on humans, implicating specific microbes in the elderly brain, notably herpes simplex virus type 1 (HSV1), Chlamydia pneumoniae, and several types of spirochaete, in the etiology of AD [1–4]. Fungal infection of AD brain [5, 6] has also been described, as well as abnormal microbiota in AD patient blood [7]. The first observations of HSV1 in AD brain were reported almost three decades ago [8]. The ever-increasing number of these studies (now about 100 on HSV1 alone) warrants re-evaluation of the infection and AD concept.

AD is associated with neuronal loss and progressive synaptic dysfunction, accompanied by the deposition of amyloid-β (Aβ) peptide, a cleavage product of the amyloid-β protein precursor (AβPP), and abnormal forms of tau protein, markers that have been used as diagnostic criteria for the disease [9, 10]. These constitute the hallmarks of AD, but whether they are causes of AD or consequences is unknown. We suggest that these are indicators of an infectious etiology. In the case of AD, it is often not realized that microbes can cause chronic as well as acute diseases; that some microbes can remain latent in the body with the potential for reactivation, the effects of which might occur years after initial infection; and that people can be infected but not necessarily affected, such that ‘controls’, even if infected, are asymptomatic [2].

Regarding HSV1, about 100 publications by many groups indicate directly or indirectly that this virus is a major factor in the disease....The only opposing reports, two not detecting HSV1 DNA in elderly brains and another not finding an HSV1–APOE association, were published over a decade ago [76–78]. However, despite all the supportive evidence, the topic is often dismissed as ‘controversial’. One recalls the widespread opposition initially to data showing that viruses cause some types of cancer, and that a bacterium causes stomach ulcers.

In summary, we propose that infectious agents, including HSV1, Chlamydia pneumonia, and spirochetes, reach the CNS and remain there in latent form. These agents can undergo reactivation in the brain during aging, as the immune system declines, and during different types of stress (which similarly reactivate HSV1 in the periphery). The consequent neuronal damage— caused by direct viral action and by virus-induced inflammation— occurs recurrently, leading to (or acting as a cofactor for) progressive synaptic dysfunction, neuronal loss, and ultimately AD.

AD causes great emotional and physical harm to sufferers and their carers, as well as having enormously damaging economic consequences. Given the failure of the 413 trials of other types of therapy for AD carried out in the period 2002–2012 [79], antiviral/antimicrobial treatment of AD patients, notably those who are APOE ɛ 4 carriers, could rectify the ‘no drug works’ impasse. We propose that further research on the role of infectious agents in AD causation, including prospective trials of antimicrobial therapy, is now justified.

Brain aging can be viewed as having 2 parts: chronological age (normally  the brain grey matter volume slowly shrinks with advancing age) and a lifetime of exposures - which can be negative from unhealthy lifestyle and injuries, and positive from a healthy lifestyle and enriched environments. That's why after a lifetime there can be wide variation in the physiological age of our brains. These differences in the  brain (in the grey matter) can be measured with magnetic resonance imaging (MRIs).

The researchers in this study used the concept of physiological age - the difference between the chronological age and predicted age, as a marker of brain health. They looked at adults of varying ages,and found that the more flights of stairs a person climbs daily, and the more years of school a person had completed, the "younger" their brain physically appears.  This study was a cross-sectional study and so shows an association rather than a definite cause, but interestingly other forms of exercise did not show this link (walking/hiking, jogging, running, bicycling, aerobic exercise, lap swimming, tennis.squash/racquetball, low intensity exercise). From Science Daily:

Want a younger brain? Stay in school -- and take the stairs

Taking the stairs is normally associated with keeping your body strong and healthy. But new research shows that it improves your brain's health too -- and that education also has a positive effect. In a study recently published in the journal Neurobiology of Aging, researchers led by Jason Steffener, a scientist at Concordia University's Montreal-based PERFORM Centre, show that the more flights of stairs a person climbs, and the more years of school a person completes, the "younger" their brain physically appears.

The researchers found that brain age decreases by 0.95 years for each year of education, and by 0.58 years for every daily flight of stairs climbed -- i.e., the stairs between two consecutive floors in a building.

For the study, Steffener and his co-authors used magnetic resonance imaging (MRI) to non-invasively examine the brains of 331 healthy adults who ranged in age from 19 to 79. They measured the volume of grey matter found in participants' brains because its decline, caused by neural shrinkage and neuronal loss, is a very visible part of the chronological aging process. Then, they compared brain volume to the participants' reported number of flights of stairs climbed, and years of schooling completed. 

Results were clear: the more flights of stairs climbed, and the more years of schooling completed, the younger the brain. "This study shows that education and physical activity affect the difference between a physiological prediction of age and chronological age, and that people can actively do something to help their brains stay young," he says.

A new study has confirmed an association between proton pump inhibitors (PPIs) — drugs that treat heartburn, peptic ulcers, and other acid-related disorders of the upper gastrointestinal tract — and increased risk for dementia in older patients. An earlier study by the same researchers found the same link between PPI use and dementia risk. The drugs work by lowering the amount of acid produced by the stomach. PPIs are among the most frequently prescribed drugs, and include omeprazole (Losec), esomeprazole (Nexium), lansoprazole (Prevacid), and the over-the-counter medication Olex.

The U.S. Food and Drug Administration have warned people to take them for the shortest period possible, namely a few weeks, and only for serious acid reflux, ulcers, or stomach bleeding. Other problems linked to long-term use are: fractures, pneumonia, increased rates of C. difficile, low magnesium levels, and chronic kidney disease. From Science Daily:

Proton pump inhibitors may be associated with increased risk of Dementia

The use of proton pump inhibitors, the popular medications used to treat gastroesophageal reflux and peptic ulcers, may be associated with an increased risk of dementia in a study using data from a large German health insurer, according to an article published online by JAMA Neurology.  The use of proton pump inhibitors (PPIs) has increased among older patients and PPIs are among the most frequently used classes of drugs.

Britta Haenisch, Ph.D., of the German Center for Neurodegenerative Diseases, Bonn, Germany, and coauthors examined the association between the use of PPIs and the risk of dementia using data from 2004 to 2011 on inpatient and outpatient diagnoses and drug prescriptions. Regular PPI use was at least one PPI prescription in each quarter of an 18-month interval.

The study population included 218,493 individuals 75 or older before 144,814 individuals were excluded, leaving 73,679 individuals included in the final analysis. The authors identified 29,510 patients who developed dementia during the study period. Regular users of PPIs (2,950 patients, mostly female and average age nearly 84) had a 44 percent increased risk of dementia compared with those (70,729 patients, mostly female and average age 83) not receiving PPI medication, according to the results.

"The present study can only provide a statistical association between PPI use and risk of dementia. The possible underlying causal biological mechanism has to be explored in future studies. 

Another famous long-running study (Framingham Heart Study) finds more bad news for middle-aged coach-potatoes (that is, those who don't exercise or have poor physical fitness). It's an observational study (thus they found an association), but the finding is pretty damn convincing: that poor physical fitness (basically a sedentary life-style) may be linked to a smaller brain size (brain volume) 20 years later. The reason this is significant is because shrinking brain volume means that accelerated brain aging is occurring.

Researcher Nicole Spartano said: "Brain volume is one marker of brain aging. Our brains shrink as we age, and this atrophy is related to cognitive decline and increased risk for dementia. So, this study suggests that people with poor fitness have accelerated brain aging." Bottom line: if you don't get much exercise or lead a sedentary life-style, then increase your activity levels for hopefully better brain health decades later. Just getting out daily (or several times a week) and walking briskly would improve fitness. From Medical Xpress:

Couch potatoes may have smaller brains later in life

Poor physical fitness in middle age may be linked to a smaller brain size 20 years later, according to a study published in the February 10, 2016, online issue of Neurology, the medical journal of the American Academy of Neurology."We found a direct correlation in our study between poor fitness and brain volume decades later, which indicates accelerated brain aging," said study author Nicole Spartano, PhD, with Boston University School of Medicine in Boston.

For the study, 1,583 people enrolled in the Framingham Heart Study, with an average age of 40 and without dementia or heart disease, took a treadmill test. They took another one two decades later, along with MRI brain scans. The researchers also analyzed the results when they excluded participants who developed heart disease or started taking beta blockers to control blood pressure or heart problems; this group had 1,094 people. 

The participants had an average estimated exercise capacity of 39 mL/kg/min, which is also known as peak VO2, or the maximum amount of oxygen the body is capable of using in one minute. Exercise capacity was estimated using the length of time participants were able to exercise on the treadmill before their heart rate reached a certain level. For every eight units lower a person performed on the treadmill test, their brain volume two decades later was smaller, equivalent to two years of accelerated brain aging. When the people with heart disease or those taking beta blockers were excluded, every eight units of lower physical performance was associated with reductions of brain volume equal to one year of accelerated brain aging.

The study also showed that people whose blood pressure and heart rate went up at a higher rate during exercise also were more likely to have smaller brain volumes two decades later. Spartano said that people with poor physical fitness often have higher blood pressure and heart rate responses to low levels of exercise compared to people with better fitness. Spartano noted that the study is observational. It does not prove that poor physical fitness causes a loss of brain volume; it shows the association. (Link to study in journal Neurology.)

This study found that greater intake of dietary nitrate and green leafy vegetables was associated with a 20 percent to 30 percent lower risk of primary open-angle glaucoma (POAG), which is the most common form of glaucoma. Glaucoma can lead to vision loss and even blindness (if left untreated).There is evidence that nitric oxide has a role in primary open-angle glaucoma, and that dietary intake of nitrates is beneficial. Green leafy vegetables (iceberg lettuce, romaine lettuce,  mustard, or chard, cooked spinach, and raw spinach) were found to be most beneficial, as well as kale and collard greens. Those who ate the most green leafy vegetables ate about 1.5 servings per day, versus .3 servings daily in the lowest intake group.

Dietary nitrate is predominately derived from green leafy vegetables, which contribute approximately 80% of nitrate intake. But they are found as well in other vegetables, such as beets and carrots. It should be pointed out that those who consumed the most dietary nitrate in this study also consumed more fruits and vegetables, and so also consumed more dietary carotenoids, vitamin C, vitamin E, flavonoids, folate, and vitamin A. Bottom line: try to eat fruits and vegetables daily, especially green leafy vegetables (e.g., a salad). From Science Daily:

Higher dietary nitrate, green leafy vegetable intake associated with lower risk of glaucoma

Greater intake of dietary nitrate and green leafy vegetables was associated with a 20 percent to 30 percent lower risk of primary open-angle glaucoma, according to a study published online by JAMA Ophthalmology.

Elevated intraocular pressure and impaired autoregulation of optic nerve blood flow are implicated in primary open-angle glaucoma (POAG; optic nerve damage from multiple possible causes that is chronic and progresses over time). Evidence suggests that nitrate or nitrite, precursors for nitric oxide, is beneficial for blood circulation. Jae H. Kang, Sc.D., of Brigham & Women's Hospital and Harvard Medical School, Boston, and colleagues evaluated the association between dietary nitrate intake, derived mainly from green leafy vegetables, and POAG. The researchers followed up participants biennially in the prospective cohorts of the Nurses' Health Study (63,893 women; 1984-2012) and the Health Professionals Follow-up Study (41,094 men; 1986-2012). Eligible participants were 40 years or older, were free of POAG, and reported eye examinations. Information on diet was updated with questionnaires.

During follow-up, 1,483 incident cases of POAG were identified. Participants were divided into quintiles (one of five groups) of dietary nitrate intake (quintile 5, approximately 240 mg/d; quintile 1, approximately 80 mg/d). The researchers found that greater intake of dietary nitrate and green leafy vegetables was associated with a 20 percent to 30 percent lower POAG risk; the association was particularly strong (40 percent-50 percent lower risk) for POAG with early paracentral visual field loss (a subtype of POAG linked to dysfunction in blood flow autoregulation). 

Of course! Makes sense that people who have a higher sense of purpose in life are at lower risk of death and cardiovascular disease!. From Science Daily:

Sense of purpose in life linked to lower mortality and cardiovascular risk

People who have a higher sense of purpose in life are at lower risk of death and cardiovascular disease, reports a pooled data analysis."Possessing a high sense of purpose in life is associated with a reduced risk for mortality and cardiovascular events," according to the study by Drs. Randy Cohen and Alan Rozanski and colleagues at Mt. Sinai St. Luke's-Roosevelt Hospital, New York. While the mechanisms behind the association remain unclear, the findings suggest that approaches to strengthening a sense of purpose might lead to improved health outcomes.

Using a technique called meta-analysis, the researchers pooled data from previous studies evaluating the relationship between purpose in life and the risk of death or cardiovascular disease. The analysis included data on more than 136,000 participants from ten studies -- mainly from the United States or Japan. The US studies evaluated a sense of purpose or meaning in life, or "usefulness to others." The Japanese studies assessed the concept of ikigai, translated as "a life worth living."

The study participants, average age 67 years, were followed up for an average of seven years. During this time, more than 14,500 participants died from any cause while more than 4,000 suffered cardiovascular events (heart attack, stroke, etc).

The analysis showed a lower risk of death for participants with a high sense of purpose in life. After adjusting for other factors, mortality was about one-fifth lower for participants reporting a strong sense of purpose, or ikigai. A high sense of purpose in life was also related to a lower risk of cardiovascular events. Both associations remained significant on analysis of various subgroups, including country, how purpose in life was measured, and whether the studies included participants with pre-existing cardiovascular disease..

There is a well-documented link between "negative psychosocial risk factors" and adverse health outcomes, including heart attack, stroke, and overall mortality. "Conversely, more recent study provides evidence that positive psychosocial factors can promote healthy physiological functioning and greater longevity," according to the authors.

While further studies are needed to determine how purpose in life might promote health and deter disease, preliminary data suggest a few basic mechanisms. The association might be explained physiologically, such as by buffering of bodily responses to stress; or behaviorally, such as by a healthier lifestyle.

Data from 2 huge studies was analyzed and found that vigorous exercise and other healthy habits seems to cut the chance of developing aggressive and lethal prostate cancer up to 68 percent in men over 60. The beneficial lifestyle habits are: weekly vigorous exercise or activity to the point of sweating, at least 7 servings of tomatoes a week, at least one serving of fatty fish per week, reduced intake of processed meat, and being a long-term non-smoker.

Interestingly, vigorous activity or exercise to sweating - ideally up to 3 hours a week - showed the biggest association with a 34 % reduced risk of aggressive prostate cancer.

From Science Daily: Working up a sweat may protect men from lethal prostate cancer

A study that tracked tens of thousands of midlife and older men for more than 20 years has found that vigorous exercise and other healthy lifestyle habits may cut their chances of developing a lethal type of prostate cancer by up to 68 percent.

While most prostate cancers are "clinically indolent," meaning they do not metastasize and are nonlife-threatening, a minority of patients are diagnosed with aggressive disease that invades the bone and other organs, and is ultimately fatal. Lead author Stacey Kenfield, ScD, of UCSF, and a team of researchers at UCSF and Harvard, focused on this variant of prostate cancer to determine if exercise, diet and smoke-free status might have life-saving benefits.

In the study, published in the Journal of the National Cancer Institute, the researchers analyzed data from two U.S. studies: the Health Professionals Follow-Up Study that tracked more than 42,000 males ages 40 to 75, from 1986 to 2010; and a second, the Physicians' Health Study that followed more than 20,000 males ages 40 to 84, from 1982 to 2010.

To gage the effects of lifestyle habits, the researchers developed a score based on the results of the health professionals survey, then applied it to the physicians' study. They assigned one point for each affirmative response to questions about regular intense exercise that induced sweating, body mass index (BMI) under 30, tobacco-free status for a minimum of 10 years, high intake of fatty fish, high intake of tomatoes and low intake of processed meat.

The researchers identified 576 cases of lethal prostate cancer in the health professionals' group and 337 cases in the physicians' group. Participants with 5 to 6 points in the health professionals' group had a 68 percent decreased risk of lethal prostate cancer and a 38 percent decreased risk was observed in the physicians' group for the same comparison.

"We estimated that 47 percent of lethal prostate cancer cases would be prevented in the United States if men over 60 had five or more of these healthy habits," said Kenfield, assistant professor in the Department of Urology at UCSF Medical Center, and formerly of the Department of Medicine at Harvard Medical School in Boston, where the study was initiated.

"It's interesting that vigorous activity had the highest potential impact on prevention of lethal prostate cancer. We calculated the population-attributable risk for American men over 60 and estimated that 34 percent of lethal prostate cancer would be reduced if all men exercised to the point of sweating for at least three hours a week," Kenfield said.

The researchers also calculated that lethal prostate cancer among American men over 60 would be cut by 15 percent if they consumed at least seven servings of tomatoes per week and that 17 percent would be spared this diagnosis if they consumed at least one serving of fatty fish per week. Reducing intake of processed meats would cut the risk by 12 percent, they reported. In contrast, the population-attributed risk for smoking was 3 percent, largely because the majority of older American men are long-term nonsmokers.