Daging meningkatkan risiko jantung dan kanker

JAMA http://archinte.jamanetwork.com/issue.aspx?journalid=71&issueid=23009

Red Meat Consumption and Mortality
Results From 2 Prospective Cohort Studies

An Pan, PhD; Qi Sun, MD, ScD; Adam M. Bernstein, MD, ScD; Matthias B. Schulze, DrPH; JoAnn E. Manson, MD, DrPH; Meir J. Stampfer, MD, DrPH; Walter C. Willett, MD, DrPH; Frank B. Hu, MD, PhD

Background Red meat consumption has been associated with an increased risk of chronic diseases. However, its relationship with mortality remains uncertain.

Methods We prospectively observed 37 698 men from the Health Professionals Follow-up Study (1986-2008) and 83 644 women from the Nurses' Health Study (1980-2008) who were free of cardiovascular disease (CVD) and cancer at baseline. Diet was assessed by validated food frequency questionnaires and updated every 4 years.

Results We documented 23 926 deaths (including 5910 CVD and 9464 cancer deaths) during 2.96 million person-years of follow-up. After multivariate adjustment for major lifestyle and dietary risk factors, the pooled hazard ratio (HR) (95% CI) of total mortality for a 1-serving-per-day increase was 1.13 (1.07-1.20) for unprocessed red meat and 1.20 (1.15-1.24) for processed red meat. The corresponding HRs (95% CIs) were 1.18 (1.13-1.23) and 1.21 (1.13-1.31) for CVD mortality and 1.10 (1.06-1.14) and 1.16 (1.09-1.23) for cancer mortality. We estimated that substitutions of 1 serving per day of other foods (including fish, poultry, nuts, legumes, low-fat dairy, and whole grains) for 1 serving per day of red meat were associated with a 7% to 19% lower mortality risk. We also estimated that 9.3% of deaths in men and 7.6% in women in these cohorts could be prevented at the end of follow-up if all the individuals consumed fewer than 0.5 servings per day (approximately 42 g/d) of red meat.

Conclusions Red meat consumption is associated with an increased risk of total, CVD, and cancer mortality. Substitution of other healthy protein sources for red meat is associated with a lower mortality risk.

Meat is a major source of protein and fat in most diets. Substantial evidence from epidemiological studies shows that consumption of meat, particularly red meat, is associated with increased risks of diabetes,¹ cardiovascular disease (CVD),² and certain cancers.³ Several studies also suggest an elevated risk of mortality associated with red meat intake. A recent large cohort study⁶ with 10 years of follow-up found that a higher intake of total red meat and total processed meat was associated with an increased risk of mortality. However, this study did not differentiate unprocessed from processed red meat, and diet and other covariates were assessed at baseline only. Furthermore, to our knowledge, no study has examined whether substitution of other dietary components for red meat is associated with a reduced mortality risk.

Therefore, we investigated the association between red meat intake and cause-specific and total mortality in 2 large cohorts with repeated measures of diet and up to 28 years of follow-up: the Health Professionals Follow-up Study (HPFS) and the Nurses' Health Study (NHS). We also estimated the associations of substituting other healthy protein sources for red meat with total and cause-specific mortality.

Perubahan lifestyle mencegah penuaan, penyakit dan 'premature morbidity'

The Lancet Oncology, Volume 14, Issue 11, Pages 1112 - 1120, October 2013

Effect of comprehensive lifestyle changes on telomerase activity and
telomere length in men with biopsy-proven low-risk prostate cancer:
5-year follow-up of a descriptive pilot study

Prof Dean Ornish MD et al

Background
Telomere shortness in human beings is a prognostic marker of ageing,
disease, and premature morbidity. We previously found an association
between 3 months of comprehensive lifestyle changes and increased
telomerase activity in human immune-system cells. We followed up
participants to investigate long-term effects.

Methods
This follow-up study compared ten men and 25 external controls who had
biopsy-proven low-risk prostate cancer and had chosen to undergo active
surveillance. Eligible participants were enrolled between 2003 and 2007
from previous studies and selected according to the same criteria. Men
in the intervention group followed a programme of comprehensive
lifestyle changes (diet, activity, stress management, and social
support), and the men in the control group underwent active surveillance
alone. We took blood samples at 5 years and compared relative telomere
length and telomerase enzymatic activity per viable cell with those at
baseline, and assessed their relation to the degree of lifestyle changes.

Findings
Relative telomere length increased from baseline by a median of 0·06
telomere to single-copy gene ratio (T/S)units (IQR—0·05 to 0·11) in the
lifestyle intervention group, but decreased in the control group (−0·03
T/S units, −0·05 to 0·03, difference p=0·03). When data from the two
groups were combined, adherence to lifestyle changes was significantly
associated with relative telomere length after adjustment for age and
the length of follow-up (for each percentage point increase in lifestyle
adherence score, T/S units increased by 0·07, 95% CI 0·02—0·12,
p=0·005). At 5 years, telomerase activity had decreased from baseline by
0·25 (—2·25 to 2·23) units in the lifestyle intervention group, and by
1·08 (—3·25 to 1·86) units in the control group (p=0·64), and was not
associated with adherence to lifestyle changes (relative risk 0·93, 95%
CI 0·72—1·20, p=0·57).

Interpretation
Our comprehensive lifestyle intervention was associated with increases
in relative telomere length after 5 years of follow-up, compared with
controls, in this small pilot study. Larger randomised controlled trials
are warranted to confirm this finding.

Fitness trumps weight when it comes to the good cholesterol

There's no question that high levels of good cholesterol
- also known as high-density lipoprotein (HDL) - seem to be protective against heart disease. Rather than depositing fat into the blood vessels the way the "bad" cholesterol (low-density lipoprotein (LDL)) does, HDL appears to carry cholesterol away from blood vessels to the liver. From there, the liver processes it
for removal from the body.

However, adequate levels of HDL might not be enough. Several recent
studies have suggested that many cases of heart disease occur in people
with normal levels of HDL cholesterol. Consequently, some researchers
believe that even if people have adequate amounts of HDL cholesterol, it
might not work well. Such HDL may not fulfill this molecule's other
important duties in the body, such as reducing inflammation
and acting as an antioxidant.

Because exercise has the potential to protect against heart disease in a
variety of ways, Christian K. Roberts and his colleagues at UCLA tested
whether HDL in men who weight trained regularly behaved in a healthier
way than HDL in sedentary men. They found that the men who didn't
exercise were more likely than those who weight trained to have
dysfunctional HDL. Having faulty HDL was associated with numerous other
risk factors for heart disease, including high triglycerides and a
higher trunk fat mass. This finding held true regardless of the men's
weight, which suggests that maintaining a "healthy" weight isn't as
important for healthy cholesterol function as being active by regularly
performing strength training.

The article is entitled "Untrained Young Men Have Dysfunctional HDL
Compared to Strength Trained Men Irrespective of Body Weight Status." *
It appears in the Articles in Press section of Journal of Applied
Physiology, published by the American Physiological Society.

*Methodology*

The researchers worked with 90 men between the ages of 18 and 30 who
already had established exercise habits. They separated these
participants into three groups: lean men who weight trained at least
four times each week, overweight men who also weight trained at least
four times each week, and overweight men who had no structured exercise
regimen. The researchers took some basic physical measurements from the
volunteers, including height and weight, waist circumference, blood
pressure, and body composition. They tested the volunteers' muscle
strength and their carotid artery thickness (a sign of heart disease),
and they took a blood sample. The researchers analyzed that sample for a
variety of different molecules present, including cholesterol, insulin,
various markers for heart disease including triglycerides and C-reactive
protein, and sex hormones. They also checked the volunteers' HDL to see
how well it functioned as an antioxidant, a sign of how well their HDL
works in general.

*Results*

The study authors found that HDL functioned better in the participants
who had a regular weight-lifting program, regardless of their
weight-overweight exercisers' HDL has similar effectiveness as an
antioxidant as the lean exercisers' HDL cholesterol. Both groups' HDL
performed significantly better than those who didn't exercise. Such
dysfunctional HDL was associated with numerous other factors associated
with heart disease, such as elevated triglycerides and trunk fat mass.

*Importance of the Findings*

These findings suggest that regular weight training might improve HDL
function and protect against heart disease, even in those who remain
overweight. Although indices of weight were associated with HDL
cholesterol function, differences in fitness, the authors say, may be a
better measure of who has healthier functioning HDL cholesterol, and
therefore, who is at risk of heart disease.

"The role of obesity in the risk of coronary heart disease may indeed be
largely accounted for by differences in fitness," the authors say.