Does Butter Cause Fatty Liver Disease?
The usual suspects have a found a 'new' paper to defend the consumption of seed oils—the Scone Study.
Is it plausible?
Whenever one evaluates a new paper, one has to consider plausibility.
If you read that a paper on homeopathy shows a positive result, well, you have a problem. Because it’s impossible for homeopathic ‘treatments’ to do anything at all, by definition. So putatively positive result is in fact just random variation—even if the P value is less than .05.
Saturated fats cause fatty liver…
So here, when reviewing “Effects of N-6 PUFAs Compared with SFAs on Liver Fat, Lipoproteins, and Inflammation in Abdominal Obesity: A Randomized Controlled Trial” (Bjermo et al., 2012) one must examine the context, and determine if the results are plausible.
Bjermo et al. note:
“Nonalcoholic fatty liver disease (NAFLD)5 affects 25% of the adult population (1) and is strongly associated with metabolic disorders and type 2 diabetes, even independently of abdominal obesity (2, 3).”
However they fail to note that NAFLD is a recent disease. The first modern description of it was in 1980 (Ludwig et al, 1980), almost yesterday in terms of Medicine, and yet in the 32 years between Ludwig and Bjermo, the disease has gone from rare to common.
What changed?
Bjermo and colleagues, who include Ulf Risérus, the senior author, would implicitly have us believe that it’s the massive increase in saturated fat consumption that has occurred over that period, and which apparently continues to this day, as NAFLD rates continue to increase.
“SFAs have been positively related to liver fat (9, 10), whereas the essential [Ω-6] PUFA linoleic acid (18:2n26) has been inversely related to plasma alanine aminotransferase (ALT) concentrations (10).”
So they tested butter vs. “foods rich in [Ω-6] linoleic acid”. Including scones with either “baked-on sunflower oil” or “baked-on butter”. No indication of what the rest of the ingredients were, however.
The participants (one is inclined to say victims), “…were instructed to consume the given food items corresponding to ~15% of energy as linoleic acid.” This is 50% beyond the level considered to by dangerous by the U.S. National Academy of Medicine (IoM):
“An upper boundary for linoleic acid is set at 10 percent of energy for three reasons: (1) individual dietary intakes in the North American population rarely exceed 10 percent of energy, (2) epidemiological evidence for the safety of intakes greater than 10 percent of energy are generally lacking, and (3) high intakes of linoleic acid create a pro-oxidant state that may predispose to several chronic diseases, such as CHD and cancer. Therefore, an AMDR of 5 to 10 percent of energy is estimated for n-6 polyunsaturated fatty acids (linoleic acid).”
But how can SFA cause fatty liver if we are eating less of it?
So is it plausible that the epidemic of fatty liver disease is caused by our eating too much butter and too little saturated fat? See the following two images:
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