Advanced Topic: SIBO/SIFO and Anti-Aging

Should SIBO/SIFO Management Be Part of Your Anti-Aging Efforts?

sibi-sifo Classify this as a speculative piece, musings on the role of small intestinal bacterial overgrowth, SIBO, and small intestinal fungal overgrowth, SIFO, on the phenomena of aging. But a number of compelling observations are pointing towards SIBO and SIFO as being common, perhaps inevitable, consequences of life that contribute to the outward and internal physiologic processes that define aging.



Could many of the phenomena of aging therefore be a manifestation of SIBO and SIFO? And, if so, can at least some of the phenomena of aging be slowed or reversed by managing these situations?

Aging, after all, is characterized by increasing inflammation, insulin resistance, weight gain, loss of muscle/sarcopenia, declining hormones and other phenomena that at least in part could be blamed on the phenomena of SIBO and SIFO.

The evidence is incomplete to make firm associations, but consider that:
  • Up to a third of the elderly have hypochlorhydria, i.e., low or absent stomach acid due to either H. pylori infection/overgrowth or autoimmune gastritis. (Many instances of autoimmune gastritis, a process in which the stomach acid-producing parietal cells in the stomach lining are destroyed, are initiated by the gliadin protein of wheat and related grains.) Lack of stomach acid is a powerful setup for SIBO, as acid is a barrier against both bacteria descending from the stomach as well as bacteria ascending from the intestinal tract. Others have taken stomach acid-suppressing drugs such as Prilosec, Aciphex, and Protonix, so-called proton pump inhibitors, PPI, drugs, or H2-blocking drugs such as ranitidine and cimetidine, for years that likewise encourage development of SIBO.

  • It is also increasingly clear that acid reflux, a common condition that affects 10-20% of the elderly at any one time, is yet another manifestation of SIBO.

  • If we accept that blood levels of homocysteine can serve as a marker for dysbiosis due to decreased capacity for microbial production of vitamins B6, B12, and folate, should we therefore see higher homocysteine levels in the elderly? Here is a study of centenarians with median homocysteine levels of 23.8 micro mol/L—exceptionally high compared to most younger people who have levels typically around 8 micromol/L. One of the causative or contributing causes for age-related increases in homocysteine could therefore be dysbiosis or SIBO that results in proliferation of species that do not produce B vitamins. Of course, higher homocysteine levels could also be due to impaired B12 or folate intake or absorption, so the association is uncertain.

  • As people age, more and more become lactose intolerant, a marker for SIBO. In a small Australian study, for instance, of 10 elderly people with lactose intolerance, 90% had SIBO (by lactulose H2 breath testing); eradication of SIBO reversed lactose intolerance in all initially SIBO-positive participants. Likewise, in an Italian study, lactose intolerance was associated with SIBO; eradication of SIBO resulted in most people being freed from lactose (as well as fructose and sorbitol) intolerance.

  • Aging is associated with an increased inflammatory response and increased levels of inflammatory mediators, a phenomenon labeled inflammaging. No cause for this phenomenon has been identified—could it be SIBO that magnifies body-wide inflammation via lipopolysaccharide and metabolic endotoxemia?

  • It is not uncommon for the elderly to die of sepsis, i.e., blood borne infection that often has no identifiable source. The most common microorganisms recovered from the blood of people experiencing sepsis? Enterobacteriaceae such as E coli, Klebsiella pneumoniae, Streptococcus pneumoniae and other microorganisms that typically characterize SIBO.

  • While the brain tissue of young people are devoid of fungi, the brains of elderly people are riddled with fungal species, while the brains of people with dementia light up like the lights in a city when stained for fungus. Couple these findings with the fact that dementia can be provoked in animal models by injecting a small quantity of fungi into the bloodstream (along with provoking all the brain’s hallmarks of Alzheimer’s dementia such as accumulation of beta amyloid plaque and phosphorylated tau proteins), people with dementia have high levels of fungal DNA and proteins in their bloodstream and cerebrospinal fluid that bathes the brain, and that the beta amyloid plaque in the brains of people with dementia possesses potent anti-fungal properties (suggesting that beta amyloid plaque is a response to fungal infestation, not the cause of dementia, consistent with the observation that drugs that reduce amyloid plaque do not reverse or slow dementia but accelerate it). People with fungal infections typically also experience other fungal phenomena, such as fungal skin, toenail, and sinus infections—but where do the fungal infections that populate all these body regions originate? Could the large fungal repository represented by SIFO in the gastrointestinal tract be the source?

Couple this with the phenomenon of immunosenescence, ie., impairment of the immune system that people develop with aging that results in increased risk for infections. Immunosenescence occurs in the gastrointestinal tract, the seat of much of the body’s immune system, also—could this allow SIBO/SIFO to take on more ominous meaning in this setting?

Even more interesting, the oxytocin-boosting effects of our L. reuteri yogurt hugely stimulates the immune system, including increased expression of immune-protective CD4+ lymphocytes and reversal of age-related thymus involution (shrinkage), in addition to this microoganism’s capacity to colonize the upper gastrointestinal tract and produce bacteriocin antibiotics effective again Enterobacteriaceae, the species of SIBO.

It is ironic, as conscious and sentient beings who often believe that we are the ultimate arbiters of our fates, that so many facets of health, including aging, can be influenced by microscopic creatures living in our abdomens. But, as insights into the microbiome grow, it may yield interesting and effective methods to use it to our advantage.

This is just a speculation, one that will need to be explored and validated. In the meantime, there is nothing lost and potentially much to gain by:
  1. Avoiding all wheat and grains and thereby reducing potential for autoimmune gastritis and introducing undesirable changes in bowel flora composition

  2. Avoiding stomach acid-blocking drugs and instead working to identify the cause of acid reflux or hyperchlorhydria (excess stomach acid), causes such as H pylori infection or SIBO

  3. Be aware that hypochlorhydria can masquerade as acid reflux and should not be managed with PPIs or H2 blockers, but identified (e.g., serum gastrin level), then managed with strategies such as betaine HCL or vinegars added to foods

  4. Assess for H pylori and eradicate it. (You can actually do this on your own; we have an Undoctored Advanced Concept discussion on this topic.)

  5. Assess for SIBO and SIFO, then take steps to manage, as we do in the Undoctored Inner Circle programs

  6. Make and consume L reuteri yogurt

Go to Forum discussion.


I'm going to propose to you that SIBO (small intestinal bacterial overgrowth) and SIFO (small intestinal fungal overgrowth) are phenomena, intestinal phenomena, that can accelerate, or be responsible for many of the phenomena of aging. Now admittedly, the science is not fully sorted out on this, but let me tell you what arrows are pointing in that direction.

For one thing, about a third of all elderly people, in their seventies and eighties, have a condition called hypochlorhydria, that is, lack of stomach acid: one third, so, a lot. Hypochlorhydria sets you up for SIBO, and perhaps for SIFO. That's because stomach acid is a barrier, both to bacteria coming down the esophagus and into the stomach, and it's also a barrier or deterrent, against bacteria ascending up from the colon and distal ileum. So if you have hypochlorhydria, from autoimmune gastritis, or H. pylori, or low stomach acid from taking stomach acid suppressing medications, this can set you up for SIBO. That could be one way SIBO and SIFO get established and contribute to some of the phenomena of aging.

Acid reflux, which is very common among the elderly — ten to twenty percent of the elderly at any one time have acid reflux. And that is very commonly really just a sign, of SIBO.

The age-related rise in homocysteine — there's a clear-cut age-related rise in homocysteine, such that when you're young your tend to have a level of 6, 7, 8 micromolar, and it rises to teens and twenties, and occasionally higher, as you get older. Well why would that be? Well it could be poor absorption of nutrients like B6, B12, and folate, or it could be impaired bowel flora composition, because bowel flora are very good at manufacturing B vitamins, especially folate, B6 and B12, the B vitamins that have a major impact on homocysteine levels.

There are some other reasons. My point is this: if SIBO and SIFO lead to such conditions as fibromyalgia, joint pain, fatigue, skin aging, inflammation (body-wide inflammation) and all the consequences of inflammation, insulin resistance — a whole panel of unhealthy phenomena, that become exaggerated as we get older — could we therefore argue that getting control over SIBO/SIFO, and eradicating them, could that give us yet more advantage in maintaining youthfulness, or reversing some of the phenomena of aging?

I don't know, but there's nothing lost in at least trying, because you know what; if you don't address your SIBO, that leads to health problems anyway. If you don't address your SIFO, that leads to other health problems. And how about people who have both, which is very common? About 50% of the people who have SIBO also have SIFO. So, it's worth eradicating. It's worth addressing, managing, eradicating anyway, but I think that one of the nice benefits of doing so will be a very nice age-reversing effect.