Prevent your brain from shrinking

My 800th curation is a 2021 human diet and lifestyle study:

“Brain atrophy is correlated with risk of cognitive impairment, functional decline, and dementia. This study (a) examines the statistical association between brain volume (BV) and age for Tsimane, and (b) compares this association to that of 3 industrialized populations in the United States and Europe.

Tsimane forager-horticulturists of Bolivia have the lowest prevalence of coronary atherosclerosis of any studied population, and present few cardiovascular disease (CVD) risk factors. They have a high burden of infections and inflammation, reflected by biomarkers of chronic immune activation, including higher leukocytes counts, faster erythrocyte sedimentation rates, and higher levels of C-reactive protein, interleukin-6, and immunoglobulin-E than in Americans of all ages.

The Tsimane have endemic polyparasitism involving helminths and frequent gastrointestinal illness. Most morbidity and mortality in this population is due to infections.

brain volume

The Tsimane exhibit smaller age-related BV declines relative to industrialized populations, suggesting that their low CVD burden outweighs their high, infection-driven inflammatory risk. If:

  1. Cross-sectional data (which we believe are population-representative of Tsimane adults aged 40 and older) represent well the average life course of individuals; and
  2. The Tsimane are representative of the baseline case prior to urbanization;

these results suggest a ~70% increase in the rates of age-dependent BV decrease accompanying industrialized lifestyles.

Despite its limitations, this study suggests:

  • Brain atrophy may be slowed substantially by lifestyles associated with very low CVD risk; and
  • There is ample scope for interventions to improve brain health, even in the presence of chronically high systemic inflammation.

Lastly, the slow rate of age-dependent BV decrease in the Tsimane raises new questions about dementia, given the role of both infections and vascular factors in dementia risk.” “The indigenous South American Tsimane exhibit relatively modest decrease in brain volume with age despite high systemic inflammation”

I came across this study by its citation in Dr. Paul Clayton’s 2021 blog post We’ve got to get ourselves back to the garden.

Resistant starch therapy

This 2021 review subject was interactions among resistant starches and gut microbiota:

“Starch that reaches the large intestine without being fully digested is termed resistant starch (RS). Starch digestibility should be considered as a kinetic property (slower to faster) affected by host-specific factors, rather than as a binary trait (resistant or nonresistant).

RS is degraded by the colon’s complex ecosystem of microbes, triggering a cascading web of metabolic interactions. RS acts as a resource that is degraded and fermented by a hierarchy of specialized gut microbes:

  1. Primary degraders grow on RS in monoculture. They penetrate outer surfaces of intact RS granules, exposing pores and deeper concentric matrices while liberating oligosaccharides and generating metabolites like lactate and acetate.
  2. Secondary degraders grow on starch in monoculture, but degrade intact RS poorly or not at all. Instead, they may adhere to abrasions and pores on RS before participating in its degradation, and opportunistically utilize solubilized oligosaccharides produced by other RS degraders.
  3. Cross-feeders do not grow on starch in monoculture. They utilize by-products generated by upstream degraders, helping to maintain stoichiometric equilibrium and thermodynamically favorable (i.e. unconstrained) fermentation.

Together, the subsystem of microbes involved in RS degradation and fermentation participates in a complex network of cross-feeding interactions. In maintaining microbiome homeostasis, the RS nutrient web expands the scope of what could be considered a ‘beneficial’ gut microbe to a cluster of metabolically interconnected microbes.

1. Primary degraders such as acetate-producing Ruminococcus bromii are thought to be necessary for RS degradation in the human gut, where they unlock RS for other community members to degrade and ferment.

Ruminococcus genus

2. Secondary degraders possess extracellular amylases to degrade regular starch, but their contribution to initiating RS degradation is negligible compared to that of primary degraders. Instead, they may require primary degraders to erode smooth RS granule surfaces before adhering to RS and/or scavenging for ‘substrate spillover’ (i.e. excess oligosaccharides generated by primary degraders).

Eubacterium genus

Roseburia genus

3. Cross-feeders utilize starch by-products or metabolites generated by upstream RS degraders, such as acetate, lactate, formate, and succinate. Describing all known gut bacteria capable of utilizing these substrates exceeds the scope of this review, but one other example is noteworthy.

Faecalibacterium prausnitzii is a prominent butyrate-producing commensal, comprising 1.5% to 9.5% of fecal bacteria in European individuals. F. prausnitzii utilizes maltose and acetate to generate butyrate.

top 1-10 species

Microbiome sequencing data are compositional, meaning that gene amplicon read counts do not necessarily reflect bacterial absolute abundances. Instead, read counts are typically normalized to sum to 100%.

For this reason, relative abundances of smaller keystone communities (e.g. primary degraders) may increase, but appear to decrease simply because cross-feeders increase in relative abundance to a greater extent. These limitations illustrate the necessity of sufficiently powering RS interventions where microbiome composition is the primary endpoint, collecting critical baseline data and employing appropriate statistical techniques.” “Resistant starch, microbiome, and precision modulation”

Don’t count on broccoli compounds bailing out a high-fat diet’s effects on gut microbiota

Two rodent studies of mature broccoli and broccoli sprouts’ effects on a high-fat diet, with the first from 2021 investigating broccoli florets and stalks:

“Addition of broccoli florets to a HFD ameliorated insulin sensitivity. Florets further promoted gut microbiota diversity and low-grade inflammatory-associated strains.

Stalk supplementation also altered gut microbiota, leading to increased Bacteroidetes/Firmicutes ratio and levels of communities that preserve mucus layer and gut integrity while simultaneously decreasing levels of potentially harmful species.

Addition of broccoli to a HFD did not ameliorate body and tissues weight gain or food intake. Both broccoli stalks and florets did not affect fat accumulation, carbohydrate, or lipid metabolism-related parameters.” “Broccoli Florets Supplementation Improves Insulin Sensitivity and Alters Gut Microbiome Population – A Steatosis Mice Model Induced by High-Fat Diet”

A 2020 study cited by this first study investigated compounds extracted from 1-day-old broccoli sprouts:

Bioaccessibility of aliphatic glucosinolates was shown to 76.2 ± 0.6%:

aliphatic glucosinolate bioavailability

Glucoraphanin was the predominant glucosinolate with the highest bioaccessibility in broccoli, and could effectively prevent HFD-induced body weight gain in mice, especially increases in liver weight and the accumulation of lipids in adipocytes. Furthermore, supplementation with glucoraphanin reduced the level of oxidative stress, regulated genes of FAS, PPARα, CPT1 and ACOX associated with lipid metabolism, and might be associated with changes in composition of gut microbiota.” “Effect of glucoraphanin from broccoli seeds on lipid levels and gut microbiota in high-fat diet-fed mice”

This study’s title was “Effect of glucoraphanin from broccoli seeds..” although its Materials and methods section disclosed:

“1 day after germination from broccoli seeds, sprouts were boiled in water for 30 min. The resulting aqueous extract was processed by liquid solid separation and condensation and was subsequently spray-dried to yield an extract powder containing 249 mg glucoraphanin.”

Eat broccoli sprouts every day and its predecessor study demonstrated that broccoli intake every day had beneficial effects during shorter periods than either of these studies.

Both studies had many “may”, “could”, and “might” statements. Not sure that broccoli compounds / gut microbiota relationships are adequately investigated by choosing a few out of tens of thousands of gut microbiota species as both studies attempted to do.

There are too many additive / antagonistic / synergistic combinations to analyze even before reaching twenty gut microbiota species. But researchers aren’t often sponsored for studies unless they conform to existing research.

I haven’t made headway in understanding my top 10 of 42,156 gut microbiota species’ exact causes, effects, and interactions. The top three by themselves are considered beneficial:

top 1-10 species

Uncertainty is fine for now, though, with a 40-hour work week interfering. Finding out what my gut microbiota generally want and giving that to them has been a productive approach this year.

If you aren’t where you want to be, change yourself

This 2021 human study evaluated associations among epigenetic clocks and socioeconomic status:

“We conducted a comprehensive, comparative analysis of associations between various dimensions of socioeconomic status (SES) (education, income, wealth, occupation, neighbourhood environment, and childhood SES) and eight epigenetic clocks in two well-powered US ageing studies:

  • The Multi-Ethnic Study of Atherosclerosis (MESA); and
  • The Health and Retirement Study (HRS).

We found robust associations between SES measures in adulthood and the GrimAge and DunedinPoAm [Dunedin New Zealand (P)lace (o)f (A)ging (m)ethylation clock)] clocks. In the HRS, significant associations with the Levine and Yang clocks were also evident.

These associations were only partially mediated by smoking, alcohol consumption, and obesity, which suggests that differences in health behaviours alone cannot explain the SES gradient in epigenetic ageing in older adults. Further analyses revealed concurrent associations between polygenic risk for accelerated intrinsic epigenetic ageing, SES, and the Levine clock, indicating that genetic risk and social disadvantage may contribute additively to faster biological aging.” “The Socioeconomic Gradient in Epigenetic Ageing Clocks: Evidence from the Multi-Ethnic Study of Atherosclerosis and the Health and Retirement Study”

This study had a lot of squishy data. Didn’t see peer review comments, but I’d require evidence for several of these categorizations and subsequent findings.

For example, I quit smoking on February 5, 1985, the day I left my third submarine. This study would have categorized me 36 years later as a former smoker.

This categorization defied human cell turnover, with exceptions of our:

  • Cerebrum and cerebellum neurons;
  • Eye inner lens cells; and
  • Heart muscle cells.

Neither these cells nor other cells are associated with current status and quitting smoking four decades earlier. Consider that “associated” relationships don’t necessarily have any causal origins.

Another example from this study. My parents’ educational achievements of Masters degrees were during the 1950s. Pretty sure they weren’t causal to my degrees during the 1980s when I focused on advancing in the U.S. Navy.

Your responses to life events and subsequent behaviors are up to you, when and where you need them to be.

Do you feel a need to be consciously aware of who you really are? If not, unconsciously move along with the herd.


Part 3 of Make your gut microbiota happy

Continuing from Part 2, my 7/15/2021 sample found that no bad bacteria needed work. Top three reasons why this may be are:

1. I’ve eaten microwaved broccoli sprouts every day for 68 weeks now. Relevant research:

helicobacter 0

2. This is the 17th year of training my immune system every day with yeast cell wall β-glucan.


3. Basic hygiene practices such as brushing my teeth twice a day.

aggregatibacter 0