Coconut oil is healthy, … Coconut oil is bad for you. Saturated fat causes heart disease… now it doesn’t? Sigh. It seems like every few days a report comes out that “proves” that saturated fat causes all kinds of diseases. What do studies really prove?

Mouse Studies

One way of studying the health impacts of a dietary system is to feed it to rodents in a laboratory environment, and follow the unsuspecting animal over time.

Many thousands of animal studies have been done using mice or rats as models of obesity. Laboratory supply companies have rodent chow that is specifically designed to make them fat. This mouse chow is called DIO (Diet Induced Obesity). This obesity-inducing diet is sometimes referred to as a “High Fat Diet”. These DIO diets also cause the mice (or rats) to have diabetes, heart disease, and metabolic problems. Often, scientific papers are published linking high fat diets to an unfortunate list of health problems. Other papers identify saturated fat as the evil villain that’s making the poor animals sick.

Most laboratory supply companies use lard as their source of saturated fat. Research Diets Inc, a laboratory supplier, explains how their DIO rodent chow induces metabolic diseases in mice, saying, “Many high-fat diets used in laboratory animal research typically contain high saturated fat sources such as lard …. and these diets are quite capable of inducing obesity and metabolic diseases….” So scientists doing research are told up front that their furry subjects are being giving saturated fat to give them a deranged metabolism.

Already we know that:

• Lard fattens mice.
• Fat mice get heart disease, diabetes, and other diseases of inflammation.
• Lard contains saturated fat.

So, saturated fat causes health problems. Right?

The connection between saturated fat and inflammation isn’t that simple. For example, lard also contains other potentially damaging compounds that could confound the studies. Here are some examples…

A study in the 2010 Journal of NeuroImmunology is entitled Cognitive impairment following high fat diet consumption is associated with brain inflammation. This study used a DIO diet (from Research Diets Inc) based on lard to cause brain inflammation.  (ScienceDirect, 2017)

Research Diets Inc. is not the only one using lard to fatten mice. Bio-Serv is another supplier of laboratory rodent food, and they also use lard in their high fat product. (Bio-Serv, 2017) An article in the Journal of Lipid Research was Titled Influence of dietary saturated fat content on adiposity, macrophage behavior, inflammation, and metabolism: composition matters (Enos, et.al. 2012). A study found that the 12% saturated fat diet (12%-SF) caused the greatest amount of insulin resistance. Their conclusion is that inflammation is heavily influenced by saturated fat content. Here’s a clipping of the actual source of fat:

The columns on the right are the high saturated fat diets, the left are the control diets. All of the diets have 40% of calories coming from fat. The saturated fat is increased by adding lard and coconut oil. But, corn oil is known to be high in compounds that can cause inflammation! So why is saturated fat blamed on for insulin resistance? Why not blame rancid corn oil? Both lard and corn oil are also dangerously high in polyunsaturated (which I’ll call PUFA). So if rodents get fat and sick on an amalgamation of saturated fat and PUFA, why are we so quick to blame saturated fat?

Another Example

A mouse study from 2012 compared mice eating a 10% fat diet to mice eating 60% fat. The study was entitled “Increased Gut Permeability and Microbiota Change Associate with Mesenteric Fat Inflammation and Metabolic Dysfunction in Diet-Induced Obese Mice”. Their conclusion was that “High saturated fat diet induced weight gain, systemic insulin resistance and inflammation”. However, they don’t disclose the supplier of the mouse chow, and there’s no mention of the type of fat in the chow.

The “high fat” diet was 38% saturated. If the researchers had used simple algebra, they would have seen that proportions of non-saturated fats must be a lot higher than the control diet also. Aside from that, 38% is similar to the USDA’s reported saturated content of lard. Assuming lard was used in this study, the actual amount of fats in lard can differ greatly from the USDA’s estimates. Pigs that are fed grains will have a high amount of PUFA in their fat. Again, why do we assume that saturated fat is responsible for all the metabolic effects?

Problems With Lard

In almost all of these studies, lard (and other fats) are used to fatten mice and cause inflammation and obesity. They then conclude that saturated fat is bad. Why don’t we conclude that lard is not healthy? If lard is bad for us, can we blame the saturated fat? We could just as easily point to the PUFA, or any other component in lard as the culprit. Vegetable seed oils contain high levels of PUFAs, and should receive at least some of the blame here.

What The Research Really Proves

Studies clearly show that

• A severe excess of calories results in weight gain, and leads to metabolic dysfunction.
• Carbs + Fat causes mice to get fat, and insulin resistant.
• Lard is particularly detrimental to the metabolism.
• Any single nutrient, consumed in excess, can cause harm.

Perhaps lard and seed oils could be part of the problem? Let’s continue…

Toxins in Lard

Lard is a type of animal fat, and animals can store toxins in fats. Pesticide residues end up in the fat of animals. Animals higher on the food chain have more dissolved toxins. In the United States, most pigs are fed diets that are high in corn and soy. Some states allow food waste to be fed to pigs. Studies have found animal fat to be high in dioxin, DDT, veterinary residues, and chlorinated pesticides. Lard, which comes from pigs, can accumulate these toxins (Muntean et.al, 2003) (Kovacs et.al, 2009). So if a scientific study finds higher rates of inflammatory diseases in rodents that eat lard, can we blame the fat content, or could accumulated toxins be to blame? This variable is usually not controlled, nor is it accounted for in any of these studies, but could influence the outcomes.

Lard is high in Saturated Fat, or Unsaturated Fat!?!?

If lard causes heart disease, it reinforces the idea that saturated fat is the culprit. What if we consider the null hypothesis that polyunsaturated fat causes heart disease? It turns out that this this might also be a logical conclusion. The fatty acid profile of pig fat depends strongly on what the pigs are being fed. Modern pigs are eating grains, and food scraps. Grain-fed pigs have a lot more polyunsaturated fat (PUFA) in their own fat. In other words, the actual fatty acid profile used in scientific studies might be much higher in PUFA’s than is accounted for.

Why Not Coconut Oil?

If lard-fed mice are getting sick, why not use coconut oil instead? It has the advantages of being

• Lower in polyunsaturated fats, which are known to cause inflammation
• Less likely to have toxic residues from environmental pollutants

Very little research has been done comparing the health benefits of coconut oil to lard, or other popular cooking oils. Coconut oil, being high in saturated fat, is assumed guilty by association.