safa and cardiovascular_mortality_yamagishi

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Dietary intake of saturated fatty acids and mortality from cardiovascular

disease in Japanese: the Japan Collaborative Cohort Study for

Evaluation of Cancer Risk (JACC) Study

Yamagishi K et al.

Am J Clin Nutr 2010;92:759-765.

Yamagishi K et al. Am J Clin Nutr 2010;92:759-765.

Pronutritionist’s background (1/2)

• SFA intake is strongly correlated with blood LDL-cholesterol concentrations and high LDL is a strong risk factor for ischemic heart disease (IHD)

• The association between SFA intake and IHD has been controversial:– SFA intake has been shown to be positively associated with the risk

of IHD in some studies (Mann et al. 1997, Boniface et al. 2002), but not in all (Siri-Tarino et al. 2010)

– replacing SFA intake with polyunsaturated fatty acid (PUFA) has been associated with a lower risk of IHD (Jakobsen et al. 2009, Mozaffarian et al. 2010)

– however, SFA intake has been inversely associated with the progression of existing coronary atherosclerosis (Mozaffarian et al. 2004).

– recent meta-analyses/systematic reviews did not support an independent adverse effect of SFA intake on risk of IHD (Siri-Tarino et al. 2010, Mente et al. 2009).

Yamagishi K et al. Am J Clin Nutr 2010;92:759-765. www.pronutritionist.net

Pronutritionist’s background (2/2)

• The association between SFA intake and strokes has been controversial:– SFA intake has been shown to be negatively associated with the

risk of stokes in some American studies (Gillman et al 1997, Iso et al 2003) and in Swedish population (Warensjö et al. 2009),

– In some studies no association has been found between SFA intake and strokes (He et al 2004, Howard et al. 2006)

– A recent meta-analysis: SFA consumption is associated with trends towards lower risk of stroke, RR 0.81 (95 % CI=0.62-1.05) ( Siri-Tarino et al. 2010 )

– In contrast to above, in a cross sectional French study, high intake of SFA associated with increased strokes (Mahe et al. 2010)


Methods

• prospective cohort study in Japan

• n = 58 453

• age 40–79 years at baseline

• follow-up 14 years

• diet was followed with a food-frequency questionnaire


Results (1/3)

• There was an inverse association of SFA intake with – mortality from total stroke (HR 0.69)– mortality from intraparenchymal hemorrhage (HR 0.48)– mortality from ischemic stroke (HR 0.58)– mortality from cardiovascular disease (driven by strokes) (HR

0.82)

• No associations were observed between SFA and mortality from subarachnoid hemorrhage and ischemic heart disease


Hazard ratios (HR) for the highest compared with the lowest quintile of SFA intake for mortality

www.pronutritionist.netYamagishi K et al. Am J Clin Nutr 2010;92:759-765.6

HR 0.69 (p= 0.004)

HR 0.58 (p=0.01)

Results (2/3)

Results (3/3)

• In substitution models replacement of SFA with increasing MUFA, PUFA or carbohydrate intakes was positively associated with stroke mortality

• No protective effect on ischemic heart disease was found when SFA was replaced with MUFA, PUFA or carbohydrates

www.pronutritionist.netYamagishi K et al. Am J Clin Nutr 2010;92:759-765.

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The HRs of MUFA, PUFA, or carbohydrates forwhich 1% of energy was substituted for SFA


8

The HRs of MUFA, PUFA, or carbohydrates forwhich 1% of energy was substituted for SFA


9

Pronutritionist’s discussion (1/2)

• In this Japanese study, there was an inverse correlation between SFA intake and occurrence of strokes

• SFA intake in Japan is lower than in Western countries:– lowest quintile of SAFA intake was 2,5 to <11,0 g/day

– highest quintile of SAFA intake was 17,9-40,0 g/day

– the lowest quartile of intake in the Nurses’ Health Study in 1980 was 20 g/d

• In addition to low SFA intake, intake of omega-3 fatty acids is high in Japanese population, which may play a role as a background factor. Therefore, the results may not be applicable to Western populations

• However, similar inverse associations have been observed also in American (Gillman et al 1997, Iso et al 2003) and in Swedish populations between SFA intake and stroke incidence (Warensjö et al. 2009)


Pronutritionist’s discussion (2/2)

• Recent cohort trials from US did not show any association between SFA intake and strokes (He et al 2004, Howard et al. 2006)

• In contrast to prospective cohort trials case-control studies have demonstrated inverse association between SFA and stroke incidence (Mahe et al. 2010)

• There are virtually no randomized interventions scrutinizing the effect of saturated fat on strokes. Considering the wealth of data on ischemic heart disease, the lack of data on strokes is odd

• If SFA’s role in coronary heart disease is controversial, its role in stroke prevention remains even more controversial. Some studies, like the most recent one, have suggested a protective role of saturated fat in prevention of strokes

• Randomized trials investigating the effects of SFA on strokes are warranted


safa and cardiovascular_mortality_yamagishi

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