Should “inflammatory” testosterone-boosting saturated fat be avoided since it increases endotoxin

If saturated fat is good for testosterone but endotoxin bad, how can saturated fat be good if it enhances the absorption of endotoxin and causes inflammation?


Saturated fat is positively correlated with testosterone levels, as 40% is often better than 20%, depending on the amount of calories consumed or the amount of adiposity someone has.

Saturated fat “has been shown” to increase endotoxin absorption and endotoxin potently promote inflammation and lower testosterone. However, it’s important to look for the inflammatory response created by the endotoxin, since there are many kinds of endotoxin (and the test doesn’t distinguish). In short, saturated fat isn’t unique in its ability to enhance the absorption of endotoxin or cause inflammation compared to other fat sources.


  • There are many kinds of LPS, so just because you have elevated LPS in the blood, doesn’t mean it’s harmful. Check inflammatory markers.
  • The small intestine is mostly sterile, so saturated fat doesn’t enhance intestinal LPS. However, LPS that are absorbed, which are coming from food or saliva, are rapidly contained and broken down after slowly coming out of the lymphatic system.
  • The colon retains its LPS tightly. However, if it is absorbed, the liver breaks it down rapidly.
  • To reduce endotoxin and inflammation, lose excess weight, eliminate inflammatory foods you might be sensitive to and improve insulin sensitivity.

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Table of Contents

Saturated fat on testosterone

When it comes to testosterone optimization, saturated fat is the go-to fat.

Fat sources such as beef, buffalo, bison, lamb, goat, game, lean fish, dairy, coconuts and eggs.

The fats found in these sources will have the greatest testosterone boosting effect, because saturated fatty acids (SFAs) are positively associated with testosterone, monounsaturated fatty acids (MUFAs) are more or less neutral whereas polyunsaturated fatty acids (PUFAs) are will lower testosterone. 

Fats T

PUFAs might increase your LH in the short term which might seem like a good thing, but long term studies show that PUFAs lead to testicular shrinkage and dysfunction. Elevated LH is actually a sign of dysfunctional testes.

There appears to be a misunderstanding about saturated fat and some people/experts put all the saturated fats into the same category, but there are many different saturated fats, each having its own function.

For example, long-chain saturated, such as palmitic- and stearic acid (found in animal fat and cocoa butter) are more androgenic and anabolic than shorter fatty acids, such as MCT oil and lauric acid (found in coconut oil).

Stearic acid increases P450scc (which is the rate-limited step at transporting cholesterol into the testes for steroidogenesis) (R). Palmitic and stearic acid directly increases pregnenolone and DHEA production, while inhibiting cortisol production (RR).

Although the longer chain fats more anabolic, shorter chain saturated fats also seem to be pro-androgenic, as shown here that caprylic acid, a medium-chain fat found in MCT oil, is an androgen receptor agonist (R).

MCT oil – rocket fuel 

The shorter chain fats are burned very quickly for energy, whereas longer SFAs will be incorporated into cell membranes and will make cells more stable. More stable cells, which are less fluid and more structured, are more resilient to stressors, produce less inflammation, are more insulin sensitive, produce more energy, testosterone, etc. 

Research shows that animals fed a very low PUFA diet have double the testosterone of the group that was fed a higher PUFA diet (A).

On the other hand, polyunsaturated fats not only lower testosterone production but also inhibits androgens from binding to their receptors (R) and inhibit DHT formation by blocking 5-AR.

How much fat for testosterone?

There are a few variables, namely obesity, insulin resistance, total calorie intake, etc.

If someone is obese and loses weight, their testosterone can go up regardless of their fat intake.

If someone is lean and goes into a slight surplus, their fat intake doesn’t have to be very high to boost testosterone.

But let’s say that someone is insulin sensitive and eating at maintenance, then between 25-40% is generally ideal for maximizing testosterone production.

I discuss how to tweak your diet, macros, micros, lifestyle and much more in the Alpha Energy Male Course: maximizing your testosterone naturally.

Endotoxin and testosterone

Endotoxin is actually called lipopolysaccharides (LPS). A lipid molecule combined with a sugar molecule. Ultimately, the term ‘‘endotoxin’’ refers to the pro-inflammatory potential of LPS molecules.

Some LPS are much more inflammatory than others.

LPS are part of the cell wall of gram-negative bacteria which are released when they die. LPS, after absorption, binds to the TLR4 receptor, through which it induces most of its damage. We’ll discuss endotoxin in more detail in just a bit.

Many studies have found a negative correlation between LPS and testosterone levels (R). Certain LPS are potent inducers of inflammation (e.g. IL-1B, IL-6, CRP, etc.) and they also directly damage the Leydig and Sertoli cells, thus reducing testosterone. It causes direct as well as indirect damage (by increasing inflammation), which reduces testosterone.

The testes have a high expression of TLR4, which makes the Leydig cells particularly susceptible to direct LPS inhibition independent of cytokine action (R).

LPS “directly inhibits the production of testosterone by reducing steroidogenic acute regulatory protein (StAR) activity (519), a key protein involved in the initial transfer of cholesterol into mitochondria, where it is converted into testosterone. Rodent studies report that mitochondrial StAR levels fall to only 10% of baseline within 2 h of endotoxin exposure, mediated primarily by mitochondrial oxidative stress, not direct cytokine action (519). Subsequently, several hours later, indirect inhibition of Leydig cell function is mediated by the release of proinflammatory cytokines such as TNF-α, IL-1β, and IL-6, which reduce the activity of other key enzymes involved in steroidogenesis (11920). These cytokines are produced by testicular macrophages and Leydig cells themselves in response to LPS (132) plus adipose tissue (18). Therefore, the obesity-related inflammatory inhibition of testicular steroidogenesis is the net effect of a direct and rapid endotoxin-related reduction in StAR activity, followed by a delayed inhibition of steroidogenic enzymes such as cholesterol side chain cleavage (P450) by cytokines released by LPS-activated Leydig cells and macrophages plus adipose tissue independent of endotoxin exposure.” (R)

This is usually when LH and FSH remain mid-range, but testosterone starts to tank. Testicular dysfunction.

Furthermore, LPS-induced inflammation stimulates aromatase and estradiol potently inhibits steroidogenesis.

People with elevated inflammation tend to have more visceral fat and visceral fat tends to be more inflammatory. It’s a vicious cycle. LPS and visceral fat-induced inflammation (e.g. IL-6) stimulate aromatase. There is a significant inverse association between IL-6 and testosterone, which suggests an important role of low-grade visceral fat inflammation in the central hypogonadism associated with metabolic syndrome (R).

Saturated fat and endotoxin

Saturated fat has been thought to enhance the absorption of endotoxin, compared to monounsaturated fat and polyunsaturated fat.

However, here are the problems with that:

  • It hasn’t always been shown to occur in all or even most studies (R, R).
  • In the studies where saturated increases endotoxin, it’s by a very low amount
    • Example 1: 0.305 to 0.455 EU/ml || average range being 3.89 to 61.06 EU/ml) (R)
    • Example 2: 3.3 to 6.3 EU/ml when healthy non-obese subjects, 5.1 to 7.7 EU/ml, while it rose from 5.7 to 7.5 EU/ml in subjects with impaired glucose tolerance and 5.3 to 14.2 EU/ml in subjects with type 2 diabetes (R)
  • Some studies found that all fat can increase endotoxin levels.
  • An increase in endotoxin doesn’t result in an increase in inflammatory markers (IL-6, IL-8, IL-10, TNFa, CRP, etc.) (R, R, R, R, R, R, R).
    • This study found that the only marker found to consistently change in the postprandial period was IL-6. Let’s look at the stats. From a baseline of ∼1.4 pg/mL, it peaked at ∼2.9 pg/mL ∼6 h post-high fat meal. CRP, TNF-α, IL-1β, and IL-8 did not change significantly (R). The average range for IL-6 is between 0 and 43.5 pg/ml. Going from 1.4 to 2.9 is not even worth mentioning IMO. Exercising increases IL-6 much more than that (R).
  • Not all endotoxin are inflammatory. The increase in blood endotoxin doesn’t mean it’s the inflammatory endotoxin. More on that below.
  • And lastly, the endotoxin test is highly inaccurate. More on that below.
  • Saturated fat potently promotes bile flow and bile acids reduce the absorption of intestinal endotoxins (R). Bile acids also keep the small intestine sterile. More on why that’s important below.

Let’s start with endotoxin

Saturated fat is thought to enhance the absorption of endotoxin.

But here are the problems with that:

Amount of endotoxin found in our blood

This study looked at a total of 5 studies and found that the mean levels of circulating endotoxin ranged widely from 5.19 to 70.73 EU/ml in unhealthy and between 3.89 to 61.06 EU/ml in healthy control subjects. It is important to note that the range is higher than what other researchers found for healthy individuals as well as patients with NAFLD, sepsis or septic shock (where the latter ranged between 1 and 4 EU/ml, with maximum levels of 12.5 EU/ml). Further, other studies report that between 89% and 11% of patients with sepsis or septic shock, respectively, and more than 50% of other ill and hospitalized subjects had no detectable levels of endotoxin in their blood (R).

It can definitely be due to error of the test or it can be because not all LPS are created equal and cause the same amount of inflammation. More on that below.

Plus, using anti-biotics doesn’t necessarily lower LPS, but some can actually increase LPS (R). Also, antibiotics don’t do much for overall survival.

Small intestine

Fat is absorbed in the small intestine where it then enters the lymphatic system. So the endotoxin doesn’t go straight to the blood. This is an extremely important point because the small intestine is relatively sterile (free of bacteria and endotoxin). What LPS is being absorbed when there are no LPS in the small intestine?

Most bacteria (and LPS) are in the mouth and colon. Fat doesn’t enhance the absorption of endotoxin from either of those areas. So clearly, the low number of bacteria in the small intestine, therefore, suggests that the majority of the LPS that are absorbed come from either the oral microbiome or from the food itself (R, R, R, R).

LPS absorbed from the small intestine

Most of the natural routes to the blood are via lymphatic channels, not veins; they deliver smaller amounts of endotoxin into the blood gradually (and intermittently) over time, and they provide more opportunities for the body’s LPS-neutralizing mechanisms (see below) to do their job.” (R)

Saturated fat carries LPS into the lymphatic system via chylomicrons. The process is very slow and the “substance” in the lymphatic system is very slowly released into the blood. This gives the body ample time to bind, transport and degrade the LPS as they trickle out.

Some of the LPS inactivation mechanisms include:

  • LPS binding protein (LBP) and phospholipid transfer protein which passes LPS to HDL and other plasma lipoproteins (R). HDL transports the LPS to the liver from breakdown by alkaline phosphatase (ALP; also expressed in the intestine) and acyloxyacyl hydrolase (AOAH). High levels of LBP can also strip LPS from cells and prevent signaling, and other plasma proteins may also bind LPS and modulate its bioactivity.
  • Bactericidal-permeability protein binds the LPS produced by many Gram-negative bacteria and blocks lipid A bioactivity (R).
  • Alkaline phosphatase(s) produced in the small intestine and liver.
  • Macrophage acid phosphatase that dephosphorylates lipid A.
  • Lipid A phosphatase in monocytes.
  • AOAH. Made by neutrophils, monocyte-macrophages (including Kupffer cells), dendritic cells, NK (natural killer cells) cells, and renal proximal tubule cells, AOAH acts both intracellularly and in inflammatory fluids to inactivate LPS (R).
  • CD14. Plasma CD14 can quickly remove LPS from the surfaces of monocytes and transfer it to HDL (R)
  • Gelsolin, a highly conserved plasma protein, binds LPS and neutralizes its stimulatory potency [133], as do lactoferrin [134], albumin, and other plasma proteins.
  • Antiendotoxin antibodies may bind O-antigen, core, or lipid A moieties, and the resulting immune complexes are cleared rapidly from the blood; the antibodies can neutralize LPS (R)

So as you can see, LPS are transported very slowly in the lymphatic system where it doesn’t cause inflammation. Once out (which is a very slow process) it’s rapidly neutralized.


LPS are created by gram-negative (GN) bacteria, which are found in the colon. So technically, the number of bacteria necessary to cause disease needs to be very high, to create all the LPS. However, in experimental rabbit and canine models of GN bacteremia with either E. coli or Pasteurella sp. bacterial challenge, GN bacteremias at levels of ∼10,000 CFU/ml corresponded to endotoxemia levels of 10 ng/ml, 500 ng/ml, and 50 EU/ml (∼5 ng/ml). Note, that these bacteremia levels are approximately 1,000 times higher than those typically seen in sepsis in humans (R). So even with a massive excess of GN bacteria and LPS, it’s highly unlikely to cause sepsis. And this is because bacteria and LPS are contained in the colon.

LPS concentrations are much higher in the colon than in the small intestine and most of the LPS that is detected in peripheral venous blood translocates from the small intestine, not the colon (R). So clearly, if all the LPS are in the colon, but fat absorption is happening in the small intestine, which LPS is the fat absorbing?

Normally, colonic bacteria (and their LPS) are prevented from entering the circulation by a combination of tight junctions between epithelial cells, the colonic mucous barrier, and neutralizing secretory IgA antibodies. However, in obesity this barrier is impaired, resulting in the passage of bacterial endotoxin into the circulation, where it elicits a systemic inflammatory response through activation of Toll-like receptor 4 (TLR4) expressed on innate immune cells (R).

Furthermore, the relatively small surface area of the colon is significantly smaller compared to the small intestine (∼0.35 m2 vs. 300 m2 due to the presence of villi in the small intestine), so even if endotoxin absorption occurs there, it will be significantly less (R). Also, the absorption of endotoxin from the colon goes straight to the liver (as opposed to the lymphatic system). And the liver is very well equipped to detox LPS right away via the enzymes alkaline phosphatase (ALP; also expressed in the intestine) and acyloxyacyl hydrolase (AOAH).

AOAH treatment produces LPS with a tetraacyl lipid A moiety that is ∼100-fold less stimulatory to human cells than is fully acylated LPS (R). So let’s say we are absorbing LPS, but they are mild to non-stimulating to the TLR4 receptor to begin with, and then AOAH further breaks it down to even weaker metabolites. Are LPS really a concern then?

Different kinds of LPS

LPS binds to the endotoxin receptor, TLR4, and different LPS structures have different effects on that receptor. Certain bacteria create strong agonists, others are weak agonists and others even have antagonistic effects.

Optimal LPS recognition by MD-2–TLR4, the host LPS receptor complex, occurs when the lipid A moiety of LPS has 6 fatty acyl chains and 2 phosphates (Fig. 2D, left). This structure is found in the LPSs produced by most Enterobacteriaceae and certain other Gram-negative aerobes, whereas the LPSs produced by Pseudomonas aeruginosa, Burkholderia sp., and many others often have 5 acyl chains and are usually less stimulatory to human cells. The tetraacyl LPSs of Yersinia pestis and Francisella tularensis are even less stimulatory. Unlike enterobacterial LPS, the LPSs made by most Bacteroides sp. and many other Gram-negative anaerobes lack the 4′-phosphate, have 5 acyl chains, and are very weak agonists; some may even inhibit the ability of E. coli LPS to stimulate human cells in vitro” (R)

Another example: LPS from E. coli is stimulatory, whereas LPS from B. fragilis antagonizes its stimulatory effect (R). So it’s more so the ratio of different LPS that matters. Even if you absorb inflammatory LPS, you’ll also absorb antagonistic LPS.

As you can see, LPS differ a lot and there are many different kinds of LPS. And not just between different species, but even in the same species. E.g. Porphyromonas gingivalis bacteria produce LPSs that are TLR4 agonists, TLR4 antagonists, or nonstimulatory (R).

And the test doesn’t know which one is which. It doesn’t know if it’s highly inflammatory, weakly inflammatory, non-stimulatory or has antagonistic effects.

Ultimately, it’s not the number of LPS that matters, but rather TLR4 stimulation. This study found that “Surprisingly, TLR4-stimulants were found to be present at much lower concentrations (1–25 g E. coli LPS equivalents per gramme) than were predicted by simple extrapolation from the number of Gram negative bacteria present in the large intestine, in which case a figure of around ∼1 mg LPS/g would have been expected. An explanation for this was found in the discovery that LPS of diverse Bacteroides species, which are the most numerous Gram-negative group in the gut outnumbering enterobacteria at least 1000:1, did not stimulate TLR4 signalling.” (R)

In this study, we performed computational and experimental analyses of healthy human fecal samples to examine the TLR4 signaling capacity of the gut microbiota. These analyses revealed that an immunoinhibitory activity of LPS, conserved across the members of the order Bacteroidales and derived from an underacylated structural feature, silences TLR4 signaling for the entire consortium of organisms inhabiting the human gut… These findings challenge the current belief that robust TLR4 signaling is a feature of the microbiome and demonstrate that microbiome-derived LPS has the ability to facilitate host tolerance of gut microbes.” (R)

This study shows that an important proinflammatory pathway that is commonly triggered by pathogenic bacteria upon interaction with the host is, in fact, actively repressed by the bacteria of the gut microbiome, supporting the idea that beneficial microbes themselves contribute to the immune tolerance in support of homeostasis. These findings are important for two reasons. First, many currently assume that proinflammatory signaling by lipopolysaccharide is a fundamental feature of the gut flora. This assumption influences greatly how host-microbiome interactions are theoretically modeled but also how they are experimentally studied, by using robust TLR signaling conditions to simulate commensals. Second, elucidation of the mechanisms that support host-microbe tolerance is key to the development of therapeutics for both intestinal and systemic inflammatory disorders.” (R)

Raising LPS artificially

It’s extremely important to know where the endotoxin came from, how the experiment was done, how they tested it, etc, etc.

With all the above information, it feels like I have debunked LPS. However, I’m not denying that LPS can be a problem. Since there are studies showing that LPS injection causes inflammation, lowers testosterone, causes fever and even death.

Injecting endotoxin can produce “sickness behavior” in healthy men, which is characterized by impaired mood, anxiety, and social disconnection (R).

However, there is a massive difference between absorbing LPS from the colon or small intestine and injection into a vein.

Much has been learned from the “volunteer endotoxemia” model [3536], but intravenous LPS injection resembles no natural condition other than, perhaps, the infusion of contaminated intravenous fluids [37]. It is not surprising that a small dose of E. coli LPS, injected directly into the bloodstream, can elicit fever and other responses in volunteers. Most of the natural routes to the blood are via lymphatic channels, not veins; they deliver smaller amounts of endotoxin into the blood gradually (and intermittently) over time, and they provide more opportunities for the body’s LPS-neutralizing mechanisms (as discussed above) to do their job.” (R)

Endotoxin test (Limulus amebocyte lysate (LAL) assay) problems

Although the LAL assay was approved by the FDA for use with pharmaceuticals and other medical products, it is not approved for the determination of endotoxin in either human or animal blood plasma or sera or for monitoring other biological fluids, presumably as these samples contain a
number of other materials that may compromise the accuracy of the test.

Problems include (R):

  • likely presence of interfering components, which may sequester or metabolize endotoxin absorbed from the gut, altering its reactivity to the LAL reagents. (R)
  • Heterogeneity in LPS structure (the test can’t distinguish between different kinds of LPS and the LPS differ in polysaccharide chain length, acylation of the lipid A backbone, and the extent to which phosphates, ethanolamine, arabinose, and other “decorations” are attached to lipid A or the core oligosaccharide (R)), solubility, physical state, and bioactivity (R)
  • Contamination during sampling of blood
  • Problems with the kinetics of the LAL reaction
  • Problems with the method of calculation
  • Problems with the sample diluent
  • Problems with sequestration of endotoxin spiked into serum or plasma
  • Variation in the endotoxin test between manufacturers and between batches
  • The LAL assay seems to be more sensitive to LPS molecules that are less endotoxic to humans, i.e. the epitopes in LPS that have been already detoxified for example by the intestinal alkaline phosphatase that is secreted into the intestinal lumen

With all those problems, it’s really hard to take any human (and animal) studies done looking at endotoxin seriously at all.


Never has blood-borne, Gram-negative bacterial endotoxin (LPS) been invoked in the pathogenesis of so many diseases—not only as a trigger for septic shock, once its most cited role, but also as a contributor to atherosclerosis, obesity, chronic fatigue, metabolic syndrome, and many other conditions.” (R)

Circulating endotoxin, usually attributed to translocation of LPS from the GI tract into the bloodstream (“intestinal endotoxemia”), has been invoked to cause or exacerbate human pathologies as diverse as atherosclerosis, alcoholic liver disease, autoimmunity, metabolic syndrome, renal injury, transplant rejection, traumatic brain injury, obesity, multiple organ failure, depression, chronic fatigue, HIV disease, and type 2 diabetes.” (R)

But with all the research I showed, one would think: “DA FAQ! It’s a mess. Why do they even do research on endotoxin?”

The research out there just shines light on a possible theory and there isn’t nearly enough research to indicate that endotoxin is a problem.

So since endotoxin is likely not a problem, saturated fat is automatically not a problem. Because even if it enhances LPS absorption slightly, it doesn’t mean anything.

What really matters

Metabolic syndrome. That’s what’s going on.

A lot of people are insulin resistant and obese and that’s causing a lot of inflammation, which then causes gut dysbiosis and low testosterone.

Diet-induced weight loss, with or without gut modulation therapy, has been shown to reduce circulating endotoxin, reduce systemic inflammation, and improve glucose homeostasis in obese individuals and T2D.” (R)

But doesn’t saturated fat cause insulin resistance and inflammation?

Nope. Saturated fat from whole fat dairy, unprocessed red meat, dark chocolate and coconut oil are saturated fat-rich foods with a complex matrix that are not associated with an increased risk of CVD, which is also caused by metabolic syndrome (R).

PUFAs on the other hand are direct precursors to endocannabinoids, which activate the endocannabinoid 1 receptor. Excess activation of the receptor causes leaky gut (R).

Gut dysbiosis and low T

I’m also not trying to deny that there isn’t a gut-testes axis. Gut dysbiosis producing inflammation can damage the testes and lower T. But again, cleaning up the diet and improving insulin sensitivity can also dramatically improve dysbiosis.

Testosterone boosting micros that also lower endotoxin

There are many micros (vitamins and minerals) that help to increase testosterone which also helps to improve gut function and lower endotoxin.

Vitamin A, D, K2, B1, B2, B3, B5, CoQ10, zinc, magnesium, etc, are essential for gut integrity (preventing LPS translocation) as well as immune modulation.

Intestinal alkaline phosphatase (iALP), which breaks down endotoxin, is increased by vit D, vit K2, zinc, taurine + butyrate, etc.


  • There are many kinds of LPS, so just because you have elevated LPS in the blood, doesn’t mean it’s harmful. Check inflammatory markers.
  • The small intestine is mostly sterile, so saturated fat doesn’t enhance intestinal LPS. However, LPS that are absorbed coming from food or saliva, are rapidly contained and broken down after slowly coming out the lymphatic system.
  • The colon retains its LPS tightly. However, if it is absorbed, the liver breaks it down rapidly.
  • To reduce endotoxin and inflammation, lose excess weight, eliminate inflammatory foods you might be sensitive to and improve insulin sensitivity.

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3 thoughts on “Should “inflammatory” testosterone-boosting saturated fat be avoided since it increases endotoxin”

  1. I’ve seen research (couldn’t find the paper now) where bile acts on intestinal bacteria environment, by neutralizing bad bacteria types and promoting lactic acid bacteria types. Saturated fat and PUFA probably stimulate different bile acids within the bile and promote different flow or effects of the bile itself.

    Killing or reducing bad bacteria will release endotoxins by nature, that’s why antibiotics can cause problems or shock to the body as well. Which in long term perspective would make sense that saturated fat is making your gut healthier and balanced by nature (like we had for millions of years).

    Hence the studies you mention don’t separate endotoxicity between PUFA’s, overall positive effects of saturated fat are still there, reduced inflammation etc. According to Ray Peat, by nature, not just by studies that we have until this point, PUFA’s are not designed for mammal consumption. Except for birds who have enzymes to break down certain constituents that repel mammals. Hence when we eat the eggs, the PUFA’s we get act different, than the PUFA’s we process.


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