When Ancel Keys started work on his
hypothesis, in 1955, he reported that butter only accounted for 4.8% of fats
consumed in the USA.[1] Remember that.It’s well-known that eggs are associated with type 2 diabetes in the USA, but there’s no such association in the rest of the world, and in Finland eggs have protective association with type 2 diabetes.
“When stratified by geographic area, there was a 39% higher risk of DM (95% CI: 21%, 60%) comparing highest with lowest egg consumption in US studies (I2 = 45.4%, P = 0.089) and no elevated risk of DM with egg intake in non-US studies (RR = 0.89; 95% CI: 0.79, 1.02 using the fixed-effect model, P < 0.001 comparing US with non-US studies). In a dose-response assessment using cubic splines, elevated risk of DM was observed in US studies among people consuming ≥3 eggs/wk but not in non-US studies.”[2]
In this chart you can see that Finland is an outlier.[3] In 2 studies, egg consumption has a protective association with type 2 diabetes.
You might well ask, does this have something to do with the way eggs are consumed? In The USA, as far as I can tell from watching TV shows, eggs are mainly consumed fried and scrambled in oil, or in cakes and pancakes. They are also consumed as egg whites. They lie around in warming drawers and skillets for most of the day being reheated, too. How are eggs consumed in Finland? The internet is pretty consistent about that. In Finland eggs are hard-boiled, then mashed up with a cup of butter. Cheese might be added.
https://www.google.co.nz/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=finland%20egg%20recipe
We know from the Malmö Diet and Cancer study that butter has protective associations with regard to type 2 diabetes.[4]
So what about CVD? There is only a little evidence on butter and CVD. Malmö again (probably the best quality epidemiological study to date) has no correlation, even non-significant, for a high intake of butter vs none.[5] EPIC-Netherland has a protective association for butter, HR 0.94 (0.90, 0.99).[6]
There are only 2 studies where butter is positively associated with CVD. In another Netherlands study, butter has no association with IHD mortality in men (1.0 ns) but an association in women - 1.08 (1.01, 1.15).[7]
A curious finding arises from another study in women in the Swedish Mammography Cohort.[8] “Whereas total dairy and cheese reportedly had inverse relationships with CVD risk, butter (as a spread) was associated with disease but total butter consumption was not.” This is perhaps explicable by the role of canola-based spread in Scandinavia; plausibly, people who use butter, but don’t eat fatty fish (which can be contaminated in inland parts of these countries), are missing out on supplemental omega 3. Certainly, Scandinavia is not the place to look for epidemiological evidence that canola spread is harmful (cooking oil or "margarine" is another story).
Anyway, the conclusion is "clear"– if you want to eat eggs, eat them with butter (and don't overcook them - boiling limits temperature to 100oC) -, and if you’re a woman and you want to eat butter, don’t eat bread.
[1] Keys A. Atherosclerosis and the diet.
SAMJ. 1955.
[2] Djoussé L, Khawaja OA, Gaziano JM. Egg consumption and risk of type 2 diabetes: a meta-analysis of prospective studies. Am J Clin Nutr. ajcn119933.
[3] Wallin A, Forouhi NG, Wolk A, Larsson SC. Egg consumption and risk of type 2 diabetes: a prospective study and dose–response meta-analysis. Diabetologia. June 2016, Volume 59, Issue 6, pp 1204–1213
http://link.springer.com/article/10.1007/s00125-016-3923-6
[4] Ericson, U, Hellstrand, S, Brunkwall, L, Schulz, C-A, Sonestedt, E, Wallström, P, et al. Food sources of fat may clarify the inconsistent role of dietary fat intake for incidence of type 2 diabetes. AJCN 2015;114.103010v1
[5] Sonestedt E, Wirfält E, Wallström P, Gullberg B, Orho-Melander M, Hedblad B. Dairy products and its association with incidence of cardiovascular disease: the Malmö diet and cancer cohort. Eur J Epidemiol. 2011 Aug;26(8):609-18. doi: 10.1007/s10654-011-9589-y. Epub 2011 Jun 10.
[2] Djoussé L, Khawaja OA, Gaziano JM. Egg consumption and risk of type 2 diabetes: a meta-analysis of prospective studies. Am J Clin Nutr. ajcn119933.
[3] Wallin A, Forouhi NG, Wolk A, Larsson SC. Egg consumption and risk of type 2 diabetes: a prospective study and dose–response meta-analysis. Diabetologia. June 2016, Volume 59, Issue 6, pp 1204–1213
http://link.springer.com/article/10.1007/s00125-016-3923-6
[4] Ericson, U, Hellstrand, S, Brunkwall, L, Schulz, C-A, Sonestedt, E, Wallström, P, et al. Food sources of fat may clarify the inconsistent role of dietary fat intake for incidence of type 2 diabetes. AJCN 2015;114.103010v1
[5] Sonestedt E, Wirfält E, Wallström P, Gullberg B, Orho-Melander M, Hedblad B. Dairy products and its association with incidence of cardiovascular disease: the Malmö diet and cancer cohort. Eur J Epidemiol. 2011 Aug;26(8):609-18. doi: 10.1007/s10654-011-9589-y. Epub 2011 Jun 10.
[6] Praagman J, Beulens JWJ, Alssema M et
al. The association between dietary saturated fatty acids and ischemic heart
disease depends on the type and source of fatty acid in the European Prospective
Investigation into Cancer and Nutrition–Netherlands cohort. Am J Clin Nutr. ajcn122671
[7] Goldbohm RA, Chorus AM, Galindo Garre F, Schouten LJ, van den Brandt PA. Dairy consumption and 10-y total and cardiovascular mortality: a prospective cohort study in the Netherlands. Am J Clin Nutr. 2011 Mar;93(3):615-27. doi: 10.3945/ajcn.110.000430. Epub 2011 Jan 26.
[7] Goldbohm RA, Chorus AM, Galindo Garre F, Schouten LJ, van den Brandt PA. Dairy consumption and 10-y total and cardiovascular mortality: a prospective cohort study in the Netherlands. Am J Clin Nutr. 2011 Mar;93(3):615-27. doi: 10.3945/ajcn.110.000430. Epub 2011 Jan 26.
[8] Patterson E, Larsson SC, Wolk A,
Akesson A. Association between dairy food consumption and risk of myocardial
infarction in women differs by type of dairy food. J Nutr. 2013;143:74–79. doi:
10.3945/jn.112.166330.