Mediterranean Diet Reduces Breast Cancer Risk

[Dean Pomerleau]

Al Pater posted [1], a study single-blind clinical trial comparing breast cancer rates among subjects assigned to two version of a Mediterranean diet (one supplemented with EVOO and one supplemented with nuts) or to a "low-fat" control diet. Actually the controls only received advice to reduce dietary fat. They didn't actually comply, since (from supplemental material) the end of trial fat intake as a percentage of total cal: Med-EVOO 41%, Med-Nut 39%, Control Diet 37%. So its really comparing a breast cancer risk between a Mediterranean diet with nuts or EVOO to a standard crappy diet.

 

What they found was that women on either the Med-EVOO diet or the Med-Nut diet had a lower risk of breast cancer, but only the Med-EVOO groups risk reduction (0.32, 95% CI, 0.13-0.79) was statistically significant. The Med-Nut group's risk was 0.59 (95% CI, 0.26-1.35) compared with controls.

 

So once again, a Mediterranean diet is shown to be good for avoiding cancer, this time breast cancer.

 

--Dean 

 

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[1] JAMA Intern Med. 2015 Nov 1;175(11):1752-60. doi: 10.1001/jamainternmed.2015.4838.

 

Mediterranean Diet and Invasive Breast Cancer Risk Among Women at High Cardiovascular Risk in the PREDIMED Trial: A Randomized Clinical Trial.

 

Toledo E, Salas-Salvadó J, Donat-Vargas C, Buil-Cosiales P, Estruch R, Ros E, Corella D, Fitó M, Hu FB, Arós F, Gómez-Gracia E, Romaguera D, Ortega-Calvo M, Serra-Majem L, Pintó X, Schröder H, Basora J, Sorlí JV, Bulló M, Serra-Mir M, Martínez-González MA.

 

Full text via sci-hub.io: http://archinte.jamanetwork.com.sci-hub.io/article.aspx?articleid=2434738

Abstract

IMPORTANCE:

Breast cancer is the leading cause of female cancer burden, and its incidence has increased by more than 20% worldwide since 2008. Some observational studies have suggested that the Mediterranean diet may reduce the risk of breast cancer.

OBJECTIVE:

To evaluate the effect of 2 interventions with Mediterranean diet vs the advice to follow a low-fat diet (control) on breast cancer incidence.

DESIGN, SETTING, AND PARTICIPANTS:

The PREDIMED study is a 1:1:1 randomized, single-blind, controlled field trial conducted at primary health care centers in Spain. From 2003 to 2009, 4282 women aged 60 to 80 years and at high cardiovascular disease risk were recruited after invitation by their primary care physicians.

INTERVENTIONS:

Participants were randomly allocated to a Mediterranean diet supplemented with extra-virgin olive oil, a Mediterranean diet supplemented with mixed nuts, or a control diet (advice to reduce dietary fat).

MAIN OUTCOMES AND MEASURES:

Breast cancer incidence was a prespecified secondary outcome of the trial for women without a prior history of breast cancer (n = 4152).

RESULTS:

After a median follow-up of 4.8 years, we identified 35 confirmed incident cases of breast cancer. Observed rates (per 1000 person-years) were 1.1 for the Mediterranean diet with extra-virgin olive oil group, 1.8 for the Mediterranean diet with nuts group, and 2.9 for the control group. The multivariable-adjusted hazard ratios vs the control group were 0.32 (95% CI, 0.13-0.79) for the Mediterranean diet with extra-virgin olive oil group and 0.59 (95% CI, 0.26-1.35) for the Mediterranean diet with nuts group. In analyses with yearly cumulative updated dietary exposures, the hazard ratio for each additional 5% of calories from extra-virgin olive oil was 0.72 (95% CI, 0.57-0.90).

CONCLUSIONS AND RELEVANCE:

This is the first randomized trial finding an effect of a long-term dietary intervention on breast cancer incidence. Our results suggest a beneficial effect of a Mediterranean diet supplemented with extra-virgin olive oil in the primary prevention of breast cancer. These results come from a secondary analysis of a previous trial and are based on few incident cases and, therefore, need to be confirmed in longer-term and larger studies.

 

PMID: 26365989

[Michael R]

All:
 

Al Pater posted [1], a study single-blind clinical trial comparing breast cancer rates among subjects assigned to two version of a Mediterranean diet (one supplemented with EVOO and one supplemented with nuts) or to a "low-fat" control diet. Actually the controls only received advice to reduce dietary fat. They didn't actually comply, since (from supplemental material) the end of trial fat intake as a percentage of total cal: Med-EVOO 41%, Med-Nut 39%, Control Diet 37%.

Yes ...
 

So its really comparing a breast cancer risk between a Mediterranean diet with nuts or EVOO to a standard crappy diet.

No ;) . Dean, I'm sure you made the above statement honestly, jumping to a premature conclusion from limited information and likely a somewhat casual reading of this report, and I would hazard almost certainly without reference to the main study results paper (2) (of which (1) was a post hoc substudy) and its key Supplementary Appendix), or the "Methods" paper for teh trial.(3) What bugs the piss out of me is others, who show clear evidence of having, at minimum, read (2) and its Appendix, and by their careful selection of words actively promote this "crappy control" diet myth when it's very clear that they know better.

When you consult those resources, two things are very apparent, in addition to the fact that (as you rightly say) the "low fat" control group wasn't actually low-fat in practice. The first is that even the baseline diets of all three groups were in multiple ways better than teh average American diet revealed eg. in NHANES, consuming more fruit and vegetables and olive oil and less saturated fat. In the breast cancer substudy(1), saturated fat intake averaged 10% of energy in all 3 groups at baseline and 9.8% after intervention in teh EVOO- and nut-supplemented Med Diet groups, while the "low-fat" controls lowered theirs to 8.8%: these are in line with the the current Dietary Guidelines for Americans (which recommend ≤10% of energy from SaFA) although somewhat higher than a recommendation from the American Heart Association (which recommend ≤7% of energy from SaFA). By contrast, the average American woman in NHANES 2009-2010 consumes 10.9% of energy as SaFA — nominally more than the Med diet groups in (1), and significantly more than consumed by the "low-fat" controls. (Men in NHANES do a hell of a lot worse on SaFA than women, unsurprisingly).

The second is that people in all three arms of the trial improved their diets: whether assigned to low-fat advice, or to Mediterranean diet with nuts or with extra-virgin olive oil, all three groups improved their scores on a standard “Mediterranean diet” assessment, and in the main study (2) cut back on saturated fat intake by 5-10% (whereas in this study, only the "low-fat" group did so). The latter was achieved even though these Spanish volunteers were already consuming significantly less saturated fat than typical Americans, Brits, or Australians when the study began. Additionally, people in the low-fat diet group cut back significantly on red and processed meat.

By far the biggest differences between the two groups assigned to Mediterranean diets and the controls was which fats they consumed. The EVOO-supplemented group increased their extra-virgin olive oil intake to about four tablespoons a day, while cutting their intake of refined olive and seed oils to almost zero. Meanwhile the group assigned to a Mediterranean diet with nuts consumed a bit less than an extra ounce of them a day. Both Mediterranean diet groups also became somewhat more regular consumers of red wine.

In fact, alcohol consumption is worth noting here. Subjects were encouraged to consume red wine ≥ 7 times/wk, since the main endpoint of the trial was to reduce CVD and events. Again, the Med diet groups in teh study as a whole (2) complied, and the controls did not. But alcohol is a well-established risk factor for breast cancer, so this really ought to have increased their risk of breast cancer. In the breast cancer substudy,(1) they don't report on red wine, but the percentage of abstainers was highest in the controls, lowest in the Med + nuts group, and intermediate in EVOO; the nut group had the highest prevalence for total alcohol intake >0 to <15 g/d, and intakes of >15 g alcohol/d was highest amongst EVOO, lowest with nuts, and intermediate for controls. This aspect of compliance to the Med diet should have increased the risk of breast cancer in the Med diet groups, especially Med + nuts.

And notably, in fact, the relative risk of breast cancer in either Med diet group vs. controls was actually more pronounced in those consuming >25 g alcohol/day (RR=0.32), showing a stronger protection than in those consuming less (RR=0.54).
 

What they found was that women on either the Med-EVOO diet or the Med-Nut diet had a lower risk of breast cancer, but only the Med-EVOO groups risk reduction (0.32, 95% CI, 0.13-0.79) was statistically significant. The Med-Nut group's risk was 0.59 (95% CI, 0.26-1.35) compared with controls.

So once again, a Mediterranean diet is shown to be good for avoiding cancer, this time breast cancer.

Yes. And, specifically, it does so relative to a still-pretty-Med-diet without active incorporation of nuts or especially EVOO.

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[1] JAMA Intern Med. 2015 Nov 1;175(11):1752-60. doi: 10.1001/jamainternmed.2015.4838.

Mediterranean Diet and Invasive Breast Cancer Risk Among Women at High Cardiovascular Risk in the PREDIMED Trial: A Randomized Clinical Trial.

Toledo E, Salas-Salvadó J, Donat-Vargas C, Buil-Cosiales P, Estruch R, Ros E, Corella D, Fitó M, Hu FB, Arós F, Gómez-Gracia E, Romaguera D, Ortega-Calvo M, Serra-Majem L, Pintó X, Schröder H, Basora J, Sorlí JV, Bulló M, Serra-Mir M, Martínez-González MA.

Full text via sci-hub.io: http://archinte.jamanetwork.com.sci-hub.io/article.aspx?articleid=2434738

PMID: 26365989

2: Estruch R, Ros E, Salas-Salvadó J, Covas MI, Corella D, Arós F, Gómez-Gracia E, Ruiz-Gutiérrez V, Fiol M, Lapetra J, Lamuela-Raventos RM, Serra-Majem L, Pintó X, Basora J, Muñoz MA, Sorlí JV, Martínez JA, Martínez-González MA; PREDIMED Study Investigators. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med. 2013 Apr 4;368(14):1279-90. doi: 10.1056/NEJMoa1200303. Epub 2013 Feb 25. PubMed PMID: 23432189.
http://dx.doi.org/10.1056/NEJMoa1200303


3: Martínez-González MÁ, Corella D, Salas-Salvadó J, Ros E, Covas MI, Fiol M, Wärnberg J, Arós F, Ruíz-Gutiérrez V, Lamuela-Raventós RM, Lapetra J, Muñoz MÁ, Martínez JA, Sáez G, Serra-Majem L, Pintó X, Mitjavila MT, Tur JA, Portillo MP, Estruch R; PREDIMED Study Investigators. Cohort profile: design and methods of the PREDIMED study. Int J Epidemiol. 2012 Apr;41(2):377-85. doi: 10.1093/ije/dyq250. Epub 2010 Dec 20. PubMed PMID: 21172932.

[AlPater]

In the MedDiet intervention groups, comparing the lowest to highest tertiles of total meat consumption, the MedDiet+EVOO group was 4.8% higher, the MedDiet+Nuts group was 0.2% lower and the low-fat control groups was 4.6% lower.  What's with that?

 

 

Replacing red meat and processed red meat for white meat, fish, legumes or eggs is associated with lower risk of incidence of metabolic syndrome.

Becerra-Tomás N, Babio N, Martínez-González MÁ, Corella D, Estruch R, Ros E, Fitó M, Serra-Majem L, Salaverria I, Lamuela-Raventós RM, Lapetra J, Gómez-Gracia E, Fiol M, Toledo E, Sorlí JV, Pedret-Llaberia MR, Salas-Salvadó J.

Clin Nutr. 2016 Mar 31. pii: S0261-5614(16)30005-X. doi: 10.1016/j.clnu.2016.03.017. [Epub ahead of print]

PMID: 27087650

http://sci-hub.io/10.1016/j.clnu.2016.03.017

 

Abstract

 

BACKGROUND & AIMS:

 

Few studies have assessed the association between consumption of red meat (RM) and processed red meats (PRM) and the incidence of metabolic syndrome (MetS) and results have been inconsistent. We investigated associations between total consumption of meat and its subtypes and incident MetS and estimated the effect of substituting RM or PRM for alternative protein-rich foods.

 

METHODS:

 

We analyzed 1868 participants (55-80 years-old) recruited into the PREDIMED study who had no MetS at baseline and were followed for a median of 3.2 years. MetS was defined using updated harmonized criteria. Anthropometric variables, dietary habits, and blood biochemistry were determined at baseline and yearly thereafter. Multivariable-adjusted hazard ratios (HRs) of MetS were estimated for the two upper tertiles (versus the lowest one) of mean consumption of meat and its subtypes during the follow-up as exposure.

 

RESULTS:

 

Comparing the highest vs the lowest tertile of consumption, we observed an increased risk of MetS incidence, with HRs of 1.23 (95% confidence interval [CI]: 1.03-1.45) and 1.46 (CI: 1.22-1.74) for total meat and pooled RM and PRM, respectively. Compared with participants in the lowest tertile, those in the highest tertile of poultry and rabbit consumption had a lower risk of MetS incidence. The risk of MetS was lower when one-serving/day of RM or PRM was replaced by legumes, poultry and rabbit, fish or eggs.

 

CONCLUSION:

 

RM and PRM consumption was associated with higher risk of MetS. Replacing RM or PRM with other protein-rich foods related to a lower risk of MetS and should, therefore, be encouraged.

 

KEYWORDS:

 

Metabolic syndrome; PREDIMED-study; Processed red meat; Red meat; Total meat