Study Concluded Replacing Dairy Fat With PUFA Calories Decreases CVD Incidence. Legit?

Elie

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Here is the abstract. Wonder if anyone has access to full text. I'd like to read the methodology.
Dairy fat and risk of cardiovascular disease in 3 cohorts of US adults. - PubMed - NCBI

Abstract
BACKGROUND:
Few prospective studies have examined dairy fat in relation to cardiovascular disease (CVD).

OBJECTIVE:
We aimed to evaluate the association between dairy fat and incident CVD in US adults.

DESIGN:
We followed 43,652 men in the Health Professionals Follow-Up Study (1986-2010), 87,907 women in the Nurses' Health Study (1980-2012), and 90,675 women in the Nurses' Health Study II (1991-2011). Dairy fat and other fat intakes were assessed every 4 y with the use of validated food-frequency questionnaires.

RESULTS:
During 5,158,337 person-years of follow-up, we documented 14,815 incident CVD cases including 8974 coronary heart disease cases (nonfatal myocardial infarction or fatal coronary disease) and 5841 stroke cases. In multivariate analyses, compared with an equivalent amount of energy from carbohydrates (excluding fruit and vegetables), dairy fat intake was not significantly related to risk of total CVD (for a 5% increase in energy from dairy fat, the RR was 1.02; 95% CI: 0.98, 1.05), coronary heart disease (RR: 1.03; 95% CI: 0.98, 1.09), or stroke (RR: 0.99; 95% CI: 0.93, 1.05) (P > 0.05 for all). In models in which we estimated the effects of exchanging different fat sources, the replacement of 5% of energy intake from dairy fat with equivalent energy intake from polyunsaturated fatty acid (PUFA) or vegetable fat was associated with 24% (RR: 0.76; 95% CI: 0.71, 0.81) and 10% (RR: 0.90; 95% CI: 0.87, 0.93) lower risk of CVD, respectively, whereas the 5% energy intake substitution of other animal fat with dairy fat was associated with 6% increased CVD risk (RR: 1.06; 95% CI: 1.02, 1.09).

CONCLUSIONS:
The replacement of animal fats, including dairy fat, with vegetable sources of fats and PUFAs may reduce risk of CVD. Whether the food matrix may modify the effect of dairy fat on health outcomes warrants further investigation.
 

marteagal

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@drk, the authors conclude that "the replacement of animal fats, including dairy fat, with vegetable sources of fats and PUFAs may reduce risk of CVD." Then, shouldn't the title of your post rather be "Study Concluded Replacing Dairy Fat With PUFA Calories Decreased CVD Incidence"? The authors seem to think that PUFAs are a good thing, in contrast to Peat's views.
 
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Prospective study. Not a randomized controlled trial. Conclusions reached based upon prejudice is much easier in such a study.

--------who is Included or excluded?

In the current analysis, we excluded men and women who had
diagnoses of diabetes, cancer, CVD, or coronary artery surgery
before completion of the baseline dietary questionnaires (15). In
addition, we excluded participants who left $10 of 131 food
items blank on the baseline FFQ (except in the NHS in 1980
when the FFQ had 61 items) or who reported unusual total
energy intakes (i.e., daily energy intake ,800 or .4200 kcal for
men and ,500 or .3500 kcal for women). We also excluded
participants without baseline information on dairy consumption
or follow-up information on the date of CVD diagnosis. After
exclusions, data from 43,652 HPFS participants, 87,907 NHS
participants, and 90,675 NHS II participants were available
for analysis (Supplemental Figure 1). The study protocol was
approved by the institutional review boards of Brigham and
Women’s Hospital and Harvard School of Public Health.

-------relative risks are really insignificant

Compared with 5% of energy intake from dairy fat, the same
amount of energy from vegetable fat was significantly associated
with a 10% decreased risk of CVD (RR: 0.90; 95% CI: 0.87,
0.93), and 11% decreased risk of CHD (RR: 0.89; 95% CI: 0.85,
0.93), and an 8% lower risk of stroke (RR: 0.92; 95% CI: 0.87, 0.97)
---------

These are so tiny in absolute terms as to be insignificant. I think.

14000 cases over 20 to 32 years out of about 210,000 people.

10% difference is 1400 out of 210,000 people over about 30 years. Too small to be meaningful.


-----all cause mortality ignored

This is the worst. Who cares about the end points other than how many more lived than died on a pufa substitution diet? We can't tell.
 

Giraffe

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Compared with 5% of energy intake from dairy fat, the same
amount of energy from vegetable fat was significantly associated
with a 10% decreased risk of CVD (RR: 0.90; 95% CI: 0.87,
0.93), and 11% decreased risk of CHD (RR: 0.89; 95% CI: 0.85,
0.93), and an 8% lower risk of stroke (RR: 0.92; 95% CI: 0.87, 0.97)
Unclear how they came to the conclusion.

Some interesting information if you look at table 1 (Baseline age adjusted characteristics)
- Intake of dairy fat is negatively associated with high cholesterol.
- The participants with the lowest intake of dairy fat had the highest incidence of hypertension.
- Energy intake around 1,800 kcal. :?:
- PUFA/Sat Fat ratio > 0.41

And then look at how they described their model:
Our basic model included age, calendar time with updated information at each 2-y questionnaire cycle, BMI, and total energy intake. We further adjusted for ethnicity, smoking, physical activity, alcohol consumption, menopausal status and menopausal hormone use (NHS and NHS II participants only), oral contraceptive use (NHS II participants only), baseline diagnosed hypertension, and hypercholesterolemia. In the final model, we further adjusted the dietary factors, including dietary intakes of fruit, vegetables, coffee, protein, vegetable fat, and other animal fat.

-----all cause mortality ignored

This is the worst.
:+1
 
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Elie

Elie

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@drk, the authors conclude that "the replacement of animal fats, including dairy fat, with vegetable sources of fats and PUFAs may reduce risk of CVD." Then, shouldn't the title of your post rather be "Study Concluded Replacing Dairy Fat With PUFA Calories Decreased CVD Incidence"? The authors seem to think that PUFAs are a good thing, in contrast to Peat's views.
Yes, I geuss my title was a bit confusing, but that the association of PUFA with healthier outcome was the thing that seemed odd to me
 
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Elie

Elie

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thanks for sharing the full copy. I will read the study design. The first thing I wanted to check quicly was whether any of the authors reported a conflict of interest (research sponsored by seed ol companies) since the study results seem to be contrary to what you'd expect from PUFA
 

Giraffe

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This is a reply to a post in another thread. I post it here because the study I use as an example was discussed here.

Now after carefully reading through giraffes critique of the several papers on the other thread, I still find it very hard to believe that not only all are of these studies somehow rigged or flawed
Most cohort studies only discuss data they already have adjusted for various factors. These studies more often than not are useless at best. In most cases you would get a better picture if they reported raw data grouped for age or only age adjusted. Sometimes they include the raw data, so you can get some rough idea how the data have been manipulated. An example is the study discussed above.

This study was about heart disease in relation to intake of dairy fat. When you look at the (almost) raw data, you see that the folk with higher intake of dairy fat had lower cholesterol levels and less incidence of hypertension. When adjusting the data they said, "Well, hypercholesterolemia and hypertension are risk factors for heart disease. Those who at baseline had a higher risk at developing heart disease, we will weigh lower." This is where everything goes wrong: Cholesterol is protective, high cholesterol is a symptom not the cause of anything. High intake of dairy fats tends to go with higher intake of calcium. When asked about hypertension, Peat has recommended to raise the calcium intake. (On pubmed you will find lots of articles on the role of PTH in CVD.)
 
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Agent207

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Prospective study. Not a randomized controlled trial. Conclusions reached based upon prejudice is much easier in such a study.
Most cohort studies only discuss data they already have adjusted for various factors. These studies more often than not are useless at best. In most cases you would get a better picture if they reported raw data grouped for age or only age adjusted.


Do you apply the same criteria on any of the studies referenced by Peat or Haidut in this forum?
 

dibble

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Harvard School of Public Health yet again promoting PUFA I see. Virtually every study I have seen in the last 5 years which is positive about PUFA comes from these guys.

One wonders why they take such an interest in it..
 

Koveras

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https://www.sciencedaily.com/releases/2016/12/161202094340.htm

Saturated fat could be good for you, study suggests
December 2, 2016
University of Bergen

Summary:
A new diet intervention study raises questions regarding the validity of a diet hypothesis that has dominated for more than half a century: that dietary fat and particularly saturated fat is unhealthy for most people.
 

Agent207

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Keeping paying attention to the "class of fat" instead of a balance between them and their specific source is relying on looking at the finger instead the moon.

All blind and categoric study posters and apologist/detractors of pufa/saturated/x as good/bad is nothing but a mockery of what human rationale should be. Looks like someone trying to defend his "fortress"; no one will progress in knowledge that way, rather will remain stuck in time forever.
 

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