In reply to:
1: Eur J Clin Nutr. 2007 May;61(5):575-81. Epub 2006 Nov 29.
Low-carbohydrate-high-protein diet and long-term survival in a general population
cohort.
Trichopoulou A, Psaltopoulou T, Orfanos P, Hsieh CC, Trichopoulos D.
Department of Hygiene and Epidemiology, School of Medicine, University of Athens,
Athens, Greece. antonia@nut.uoa.gr
OBJECTIVE: We have evaluated the effects on mortality of habitual low
carbohydrate-high-protein diets that are thought to contribute to weight control.
DESIGN: Cohort investigation. SETTING: Adult Greek population. SUBJECTS METHODS:
Follow-up was performed from 1993 to 2003 in the context of the Greek component
of the European Prospective Investigation into Cancer and nutrition. Participants
were 22 944 healthy adults, whose diet was assessed through a validated
questionnaire. Participants were distributed by increasing deciles according to
protein intake or carbohydrate intake, as well as by an additive score generated
by increasing decile intake of protein and decreasing decile intake of
carbohydrates. Proportional hazards regression was used to assess the relation
between high protein, high carbohydrate and the low carbohydrate-high protein
score on the one hand and mortality on the other. RESULTS: During 113 230 persons
years of follow-up, there were 455 deaths. In models with energy adjustment,
higher intake of carbohydrates was associated with significant reduction of total
mortality, whereas higher intake of protein was associated with nonsignificant
increase of total mortality (per decile, mortality ratios 0.94 with 95% CI 0.89
-0.99, and 1.02 with 95% CI 0.98 -1.07 respectively). Even more predictive of
higher mortality were high values of the additive low carbohydrate-high protein
score (per 5 units, mortality ratio 1.22 with 95% CI 1.09 -to 1.36). Positive
associations of this score were noted with respect to both cardiovascular and
cancer mortality.
CONCLUSION: Prolonged consumption of diets low in carbohydrates
and high in protein is associated with an increase in total mortality. Publication Types:
Research Support, Non-U.S. Gov't
PMID: 17136037 [PubMed - indexed for MEDLINE]
2: J Intern Med. 2007 Apr;261(4):366-74.
Comment in:
J Intern Med. 2007 Apr;261(4):363-5.
Low carbohydrate-high protein diet and mortality in a cohort of Swedish women.
Lagiou P, Sandin S, Weiderpass E, Lagiou A, Mucci L, Trichopoulos D, Adami HO.
Department of Hygiene and Epidemiology, University of Athens Medical School,
Goudi, Athens, Greece. plagiou@hsph.harvard.edu
OBJECTIVE: The long-term health consequences of diets used for weight control are
not established. We have evaluated the association of the frequently recommended
low carbohydrate diets - usually characterized by concomitant increase in protein
intake - with long-term mortality. DESIGN: The Women's Lifestyle and Health
cohort study initiated in Sweden during 1991-1992, with a 12-year almost complete
follow up. SETTING: The Uppsala Health Care Region. SUBJECTS: 42,237 women, 30-49
years old at baseline, volunteers from a random sample, who completed an
extensive questionnaire and were traced through linkages to national registries
until 2003. MAIN OUTCOME MEASURES: We evaluated the association of mortality
with: decreasing carbohydrate intake (in deciles); increasing protein intake (in
deciles) and an additive combination of these variables (low carbohydrate-high
protein score from 2 to 20), in Cox models controlling for energy intake,
saturated fat intake and several nondietary covariates. RESULTS: Decreasing
carbohydrate or increasing protein intake by one decile were associated with
increase in total mortality by 6% (95% CI: 0-12%) and 2% (95% CI: -1 to 5%),
respectively. For cardiovascular mortality, amongst women 40-49 years old at
enrolment, the corresponding increases were, respectively, 13% (95% CI: -4 to
32%) and 16% (95% CI: 5-29%), with the additive score being even more predictive.
CONCLUSIONS: A diet characterized by low carbohydrate and high protein intake was
associated with increased total and particularly cardiovascular mortality amongst
women. Vigilance with respect to long-term adherence to such weight control
regimes is advisable.
Publication Types:
Research Support, Non-U.S. Gov't
PMID: 17391111 [PubMed - indexed for MEDLINE]
3: N Engl J Med. 2006 Nov 9;355(19):1991-2002.
Comment in:
N Engl J Med. 2007 Feb 15;356(7):750; author reply 750-2. N Engl J Med. 2007 Feb 15;356(7):750; author reply 750-2.
Low-carbohydrate-diet score and the risk of coronary heart disease in women.
Halton TL, Willett WC, Liu S, Manson JE, Albert CM, Rexrode K, Hu FB.
Departments of Nutrition, Harvard School of Public Health, Boston, MA 02115, USA.
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. Copyright
2006 Massachusetts Medical Society.
Publication Types:
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
PMID: 17093250 [PubMed - indexed for MEDLINE]
4: Am J Clin Nutr. 2008 Feb;87(2):339-46.
Low-carbohydrate-diet score and risk of type 2 diabetes in women.
Halton TL, Liu S, Manson JE, Hu FB.
Department of Nutrition, Harvard School of Public Health, Boston, MA 02215, USA.
BACKGROUND: Low-carbohydrate weight-loss diets remain popular; however, the
long-term effects of these diets are not known. OBJECTIVE: The objective was to
examine the association between low-carbohydrate-diet score and risk of type 2
diabetes DESIGN: We prospectively examined the association between
low-carbohydrate-diet score (based on percentage of energy as carbohydrate, fat,
and protein) and risk of diabetes among 85 059 women in the Nurses' Health Study.
RESULTS: During 20 y of follow-up, we documented 4670 cases of type 2 diabetes.
The multivariate relative risk (RR) of diabetes, after adjustment for body mass
index and other covariates, in a comparison of the highest decile of
low-carbohydrate-diet score with the lowest was 0.90 (95% CI: 0.78, 1.04; P for
trend = 0.26). The multivariate RR for the comparison of extreme deciles of
low-carbohydrate-diet score based on total carbohydrate, animal protein, and
animal fat was 0.99 (95% CI: 0.85, 1.16; P for trend = 1.0), whereas the RR for a
low-carbohydrate-diet score based on total carbohydrate, vegetable protein, and
vegetable fat was 0.82 (95% CI: 0.71, 0.94; P for trend = 0.001). A higher
dietary glycemic load was strongly associated with an increased risk of diabetes
in a comparison of extreme deciles (RR: 2.47; 95% CI: 1.75, 3.47; P for trend <
0.0001)). A higher carbohydrate consumption was also associated with an increased
risk of diabetes in a comparison of extreme deciles (RR: 1.26; 95% CI: 1.07,
1.49; P for trend = 0.003).
CONCLUSION: These data suggest that diets lower in
carbohydrate and higher in fat and protein do not increase the risk of type 2
diabetes in women. In fact, diets rich in vegetable sources of fat and protein
may modestly reduce the risk of diabetes. Publication Types:
Comparative Study
Research Support, N.I.H., Extramural
PMID: 18258623 [PubMed - indexed for MEDLINE]