As promised, the skeptical cardiologist has reviewed, refurbished, republished and revised his first ever post (first published 12/27/2012) which challenged the advice presented by the Dietary Guidelines for Americans, the American Heart Association, and every mainstream nutritional guideline published since 1985.
I’ve added some links to subsequent posts which support my statements, improved the formatting, and corrected typos.
Everything that I said in this initial post has been further confirmed by subsequent scientific studies. I’ve added some comments in green. I wrote a letter to Scott Gottlieb, the FDA director in 2018 asking why he was still pushing low-fat dairy .
The post summarizes the evidence at that time:
It turns out when objectively analyzed (as I have written about here and here ) there is no scientific evidence that supports the concept that dairy processed to remove dairy fat is healthier than the original unadulterated product.
In fact, evidence suggests full fat dairy reduces central obesity, diabetes, cardiovascular disease and atherosclerosis in general. Alas, no changes have occurred in major guideline recommendations.
I do feel the scientific consensus on this is slowy (but reluctantly) shifting as reflected in a 2020 State of the art review paper in the Journal of the American College of Cardiology entitled “Saturated Fats and Health: A Reassessment and Proposal for Food-based recommendations,” which concludes a “Whole-fat dairy, unprocessed meat, and dark chocolate are SFA-rich foods with a complex matrix that are not associated with increased risk of CVD.”
However, most of those who have been making this recommendation for decades seem incapable of correcting their errors.
Dietary guidelines recommend the consumption of milk and dairy products as an important part of a healthy, well-balanced diet.
The 2010 USDA Guidelines state:
“Milk and milk products contribute many nutrients, such as calcium, vitamin D (for products fortified with vitamin D), and potassium, to the diet. Moderate evidence shows that intake of milk and milk products is linked to improved bone health, especially in children and adolescents. Moderate evidence also indicates that intake of milk and milk products is associated with a reduced risk of cardiovascular disease and type 2 diabetes and with lower blood pressure in adults.”
However, dairy fat has been portrayed as the unhealthy component of milk and dairy products, largely because it is energy-dense and a rich source of saturated fatty acids . Therefore, typical dietary advice recommends fat-reduced milk and dairy products.
Shockingly, and despite expert and government-backed recommendations, the advice to change to fat-reduced or skim milk and dairy products is not supported by any prospective scientific studies.
The main reason cited for the recommendations is that the consumption of saturated fatty acids is related to an increase in LDL cholesterol which in turn has been related to increased coronary heart disease-the major cause of heart attacks.
As we discuss this topic more, we will discover that this logic is flawed because
1) saturated fats are a diverse family of compounds with varying effects on the cholesterol profile
2) the cholesterol profile itself is incredibly complex and simple measurements of “bad” (LDL) and “good” (HDL) cholesterol alone don’t tell us enough about the risk of heart disease. (I now consider apolipoprotein B to be the primary driver of atherosclerosis)
To these points I would now add
3) The saturated fat acids (SFAs) in dairy products are delivered in a complex matrix of macro and micronutrients far different than that in other animal sources. Thus, the more complex matrix for yogurt and cheese, despite similar SFA profile to butter results in a lower LDL level (see here.)
4) Whereas since 1990 it has become clear that lowering LDL cholesterol by statins, ezetimibe, and PCSK9 inhibitors strongly reduces cardiovascular events , these benefits may not be extrapolated to the effect of dietary change on the risk (see here and here.)
Partially as a result of these guidelines, the pattern of dairy fat intake has changed considerably in the last 40 years, a time frame during which the modern obesity epidemic has developed in the United States.
Butter consumption has dropped considerably and low-fat milk has supplanted full-fat milk as the preferred product.
In parallel, dairy fat consumption has increased from other, less healthy sources such as highly processed foods and pizza. All that fat extracted from milk, yogurt and cheese to make them “healthy” has reappared in less healthy, highly processed forms.
I fact-checked myself on these dietary changes and also looked at current trends. Cheese consumption was and is still trending upward. Most of this increase in cheese consumption is in the form of pizza (see here.) I have written in defense of real cheese.
Liquid milk consumption has been declining for some time which I think is a good thing in adults. Primarily, because drinking calories is worse for weight management than eating them. Butter consumption dropped like a rock after authorities began condemning SFAs and margarine consumption soared. Once it became clear that the industrially-produced trans fats in margarine was a lot worse than butter in the early 1990s they switched trajectories.
When epidemiologists have scientifically reviewed the relationship between high fat dairy consumption and heart disease or obesity, almost invariably they have found an inverse relationship. That is, the more dairy consumed, the lower the risk of heart disease and the less obesity. (This is even more apparent in 2022, see here.)
In subsequent posts, we’ll look in more detail at the evidence supporting dairy consumption in reducing heart disease and obesity.
There are a couple of really interesting studies in this area I hope to write about in the near future
I didn’t end my first post with skeptically yours.
But I remain
Myristically Yours,
-ACP