Tuesday, November 21, 2006

Diet Rendah Karbohidrat dan Risiko Penyakit Jantung Koroner untuk Wanita

Diet rendah karbohidrat (low carb) banyak digunakan untuk menurunkan berat
badan dan mencegah obesitas. Bagaimana efek diet low carb terhadap risiko
penyakit jantung koroner (PJK)?

Penelitian yang melibatkan >82 ribu subyek dan difollow-up selama 20 tahun,
menyimpulkan terhadap risiko terjadinya PJK, diet low carb ataupun diet low
fat ternyata tidak berbeda. Kedua jenis diet - low carb maupun low fat -
mempunyai kelebihan dan kekurangan masing2.

Temuan terpenting adalah bahwa dengan memperbanyak sayuran dalam diet
(sebagai sumber protein nabati dan lemak nabati) risiko PJK dapat diturunkan
sebesar 30%. Sebaliknya konsumsi karbohidrat ber-indeks glisemik rendah
(misalnya gula) akan meningkatkan risiko PJK.

New England Journal of Medicine number 19, Volume 355:1991-2002.
Low-Carbohydrate-Diet Score and the Risk of Coronary Heart Disease in Women.
Thomas L. Halton, Sc.D., Walter C. Willett, M.D., Dr.P.H., Simin Liu, M.D.,
Sc.D., JoAnn E. Manson, M.D., Dr.P.H., Christine M. Albert, M.D., M.P.H.,
Kathryn Rexrode, M.D., and Frank B. Hu, M.D., Ph.D.

ABSTRACT

Background Low-carbohydrate diets have been advocated for weight loss and to
prevent obesity, but the long-term safety of these diets has not been
determined.
Methods We evaluated data on 82,802 women in the Nurses' Health Study who
had completed a validated food-frequency questionnaire. Data from the
questionnaire were used to calculate a low-carbohydrate-diet score, which
was based on the percentage of energy as carbohydrate, fat, and protein (a
higher score reflects a higher intake of fat and protein and a lower intake
of carbohydrate). The association between the low-carbohydrate-diet score
and the risk of coronary heart disease was examined.
Results During 20 years of follow-up, we documented 1994 new cases of
coronary heart disease. After multivariate adjustment, the relative risk of
coronary heart disease comparing highest and lowest deciles of the
low-carbohydrate-diet score was 0.94 (95% confidence interval [CI], 0.76 to
1.18; P for trend=0.19). The relative risk comparing highest and lowest
deciles of a low-carbohydrate-diet score on the basis of the percentage of
energy from carbohydrate, animal protein, and animal fat was 0.94 (95% CI,
0.74 to 1.19; P for trend=0.52), whereas the relative risk on the basis of
the percentage of energy from intake of carbohydrates, vegetable protein,
and vegetable fat was 0.70 (95% CI, 0.56 to 0.88; P for trend=0.002). A
higher glycemic load was strongly associated with an increased risk of
coronary heart disease (relative risk comparing highest and lowest deciles,
1.90; 95% CI, 1.15 to 3.15; P for trend=0.003).

Conclusions Our findings suggest that diets lower in carbohydrate and higher
in protein and fat are not associated with increased risk of coronary heart
disease in women. When vegetable sources of fat and protein are chosen,
these diets may moderately reduce the risk of coronary heart disease.

Source Information
From the Departments of Nutrition (T.L.H., W.C.W., F.B.H.) and Epidemiology
(W.C.W., J.E.M., F.B.H.), Harvard School of Public Health, Boston; the
Department of Epidemiology, University of California, Los Angeles, School of
Public Health, Los Angeles (S.L.); and the Division of Preventive Medicine
(J.E.M., C.M.A., K.R.), the Channing Laboratory (W.C.W., J.E.M., K.R.,
F.B.H.), and the Cardiovascular Division (C.M.A.), Department of Medicine,
Brigham and Women's Hospital and Harvard Medical School, Boston.

Friday, November 10, 2006

Untung Rugi Konsumsi Seafood

Para peneliti dari Harvard ingin mengetahui keuntungan dan kerugian konsumsi
seafood.

Ternyata konsumsi seafood (terutama ikan yang kaya asam lemak omega-3 berupa
DHA maupun EPA) sebanyak 1-2 porsi tiap minggu dapat menurunkan angka
kematian penyakit jantung koroner sebesar 36%.

DHA mendukung perkembangan awal sel2 saraf, sehingga ibu hamil dan menyusui
dianjurkan untuk konsumsi seafood 2 porsi tiap minggu. Kontaminasi
metil-merkuri sebaliknya menghambat perkembangan sel2 saraf, namun pengaruh
metil-merkuri untuk orang dewasa kurang nyata.

Dianjurkan mengkonsumsi beragam jenis seafood.

Kadar kontaminasi dioxin dan polychlorinated biphenyls terdeteksi rendah,
sehingga potensi karsinogeniknya juga rendah.

Disimpulkan bahwa keuntungan konsumsi beragam seafood lebih besar dibanding
efek negatifnya, termasuk untuk kelompok wanita usia subur.

Catatan untuk seafood dari perairan dengan tingkat kontaminasi lebih tinggi,
kesimpulan di atas mungkin tidak berlaku.

Abstract

JAMA
<http://jama.ama-assn.org/cgi/content/abstract/296/15/1885?etoc><http://jama
.ama-assn.org/cgi/content/abstract/296/15/1885?etoc> 2006;296:1885-1899.
Vol. 296 No. 15, October 18, 2006 © 2006 American Medical Association.
Fish Intake, Contaminants, and Human Health: Evaluating the Risks and the
Benefits.
Dariush Mozaffarian, Eric B. Rimm.

Context Fish (finfish or shellfish) may have health benefits and also
contain contaminants, resulting in confusion over the role of fish
consumption in a healthy diet.
Evidence Acquisition We searched MEDLINE, governmental reports, and
meta-analyses, supplemented by hand reviews of references and direct
investigator contacts, to identify reports published through April 2006
evaluating (1) intake of fish or fish oil and cardiovascular risk, (2)
effects of methylmercury and fish oil on early neurodevelopment, (3) risks
of methylmercury for cardiovascular and neurologic outcomes in adults, and
(4) health risks of dioxins and polychlorinated biphenyls in fish. We
concentrated on studies evaluating risk in humans, focusing on evidence,
when available, from randomized trials and large prospective studies. When
possible, meta-analyses were performed to characterize benefits and risks
most precisely.
Evidence Synthesis Modest consumption of fish (eg, 1-2 servings/wk),
especially species higher in the n-3 fatty acids eicosapentaenoic acid (EPA)
and docosahexaenoic acid (DHA), reduces risk of coronary death by 36% (95%
confidence interval, 20%-50%; P<.001) and total mortality by 17% (95%
confidence interval, 0%-32%; P = .046) and may favorably affect other
clinical outcomes. Intake of 250 mg/d of EPA and DHA appears sufficient for
primary prevention. DHA appears beneficial for, and low-level methylmercury
may adversely affect, early neurodevelopment. Women of childbearing age and
nursing mothers should consume 2 seafood servings/wk, limiting intake of
selected species. Health effects of low-level methylmercury in adults are
not clearly established; methylmercury may modestly decrease the
cardiovascular benefits of fish intake. A variety of seafood should be
consumed; individuals with very high consumption (5 servings/wk) should
limit intake of species highest in mercury levels. Levels of dioxins and
polychlorinated biphenyls in fish are low, and potential carcinogenic and
other effects are outweighed by potential benefits of fish intake and should
have little impact on choices or consumption of seafood (women of
childbearing age should consult regional advisories for locally caught
freshwater fish).
Conclusions For major health outcomes among adults, based on both the
strength of the evidence and the potential magnitudes of effect, the
benefits of fish intake exceed the potential risks. For women of
childbearing age, benefits of modest fish intake, excepting a few selected
species, also outweigh risks.

Author Affiliations: Channing Laboratory, Department of Medicine, Brigham
and Women's Hospital, and Harvard Medical School; and Departments of
Epidemiology and Nutrition, Harvard School of Public Health, Boston, Mass.

Thursday, November 2, 2006

Kopi, diabetes dan berat badan

Beberapa penelitian epidemiologi menyimpulkan bahwa kopi (baik caffeinated
maupun decaffeinated) dapat mengurangi risiko diabetes. Ini mungkin
berhubungan dengan penurunan berat badan. Penurunan berat badan diduga
berhubungan dengan kandungan kafein dan zat2 lain dalam kopi (chlorogenic
acid dan quinides). Namun kopi dapat menyebabkan kenaikan tekanan darah akut
sehingga ditakutkan akan meningkatkan risiko penyakit kardiovaskuler. Satu
penelitian singkat menyimpulkan bahwa kopi decaffeinated tidak menaikan
tekanan darah. Dengan demikian konsumsi kopi decaffeinated lebih aman dan
tetap dapat mengurangi risiko diabetes.

Abstract

American Journal of Clinical Nutrition, Vol. 84, No. 4, 682-693, October
2006
© 2006 American Society for Nutrition.
Coffee, diabetes, and weight control.
James A Greenberg, Carol N Boozer and Allan Geliebter.
From the Department of Health and Nutrition Sciences, Brooklyn College, City
University of New York, New York NY (JAB), and the Department of Medicine,
Columbia University and New York Obesity Research Center, St
Luke's-Roosevelt Hospital Center, New York, NY (NB and AG)
Several prospective epidemiologic studies over the past 4 y concluded that
ingestion of caffeinated and decaffeinated coffee can reduce the risk of
diabetes. This finding is at odds with the results of trials in humans
showing that glucose tolerance is reduced shortly after ingestion of
caffeine or caffeinated coffee and suggesting that coffee consumption could
increase the risk of diabetes. This review discusses epidemiologic and
laboratory studies of the effects of coffee and its constituents, with a
focus on diabetes risk. Weight loss may be an explanatory factor, because
one prospective epidemiologic study found that consumption of coffee was
followed by lower diabetes risk but only in participants who had lost
weight. A second such study found that both caffeine and coffee intakes were
modestly and inversely associated with weight gain. It is possible that
caffeine and other constituents of coffee, such as chlorogenic acid and
quinides, are involved in causing weight loss. Caffeine and caffeinated
coffee have been shown to acutely increase blood pressure and thereby to
pose a health threat to persons with cardiovascular disease risk. One
short-term study found that ground decaffeinated coffee did not increase
blood pressure. Decaffeinated coffee, therefore, may be the type of coffee
that can safely help persons decrease diabetes risk. However, the ability of
decaffeinated coffee to achieve these effects is based on a limited number
of studies, and the underlying biological mechanisms have yet to be
elucidated.