Tuesday, December 30, 2014

In Search of the Perfect Fiber (Part 1...quantity)

I learn so much writing this blog.  I feel very honored to have so many people who read and comment here.  My next few blog posts will relate mainly to fiber.

You've maybe clicked on the "Dietary Fiber" tab at the top.  It's kind of messy.  It's the first draft of a project I was working on last year.  Lots of good info and cites linked, but in the last few months I realized that people need more practical advice.

Friday, December 12, 2014

Raw Potato Starch; A Great Prebiotic!

The Potato Starch Experiment

Allan Folz and his family of four recently did a "crowd-funded" experiment with potato starch. They designed a dietary strategy and had a full gut analysis done on all four members, before and after the dietary intervention. This experiment could not have been conducted any better in a big university setting. The gut tests used were state-of-the-art 16s rRNA gene sampling by the American Gut Project and the raw data was obtained from the European Nucleotide Archive and double-checked using MG-rast, an open-source metogenomic analysis server.  The subjects involved two adults and two children, all healthy human subjects with no recent history of antibiotic use.

Please have a look at the experiment design, Allan's observations, and an initial look.  The data has now been analyzed. A comparison with the results of the Folz' family experiment and the criteria for "prebiotics" in Rastall and Gibson's new paper show conclusively that raw potato starch meets every available definition of the term "prebiotic."

Adult 1
Adult 2
Child 1
Child 2

                      (Green = Increased abundance    Orange = Decreased abundance)

To recap the dietary interventions:

Adult 1 - Added 4TBS of potato starch daily
Adult 2 - Added 2TBS of potato starch daily, mixed with kefir
Child 1 - Added 1TBS of potato starch daily, plus 1tsp of psyllium husk
Child 2 - Added 1TBS of potato starch daily

The dietary intervention lasted for 6 weeks, and the final fecal samples were taken on the last day.

An examination of the data shows that each subject had considerable increases in bifidobacterium, and mainly increases in the other bacteria suggested as targets for prebiotics by Rastall and Gibson. The slight decreases were most pronounced in the subject (Child 2) who ate the least amount of total fiber supplements, but ironically, this subject also had the largest increase in bifidobacteria.

The species of bifidobacteria detected in the samples were ~95% Bifidobacterium breve, with smaller amounts of animalis, dentium, longum, and pseudolongum.   

Data Confidence


The data used for this chart looks different from what Allan reported was on his American Gut report. The data presented here was derived by plugging the raw data used by American Gut into a program called MG-rast. MG-rast is an open-access metagenomics analysis tool used by researchers and universities to catalog large sets of genomic data. In all cases, the increases and declines in specific gut bacteria correlated to increases shown on the American Gut report. All of the gut reports were conducted at the same time by the American Gut Project, a crucial consideration in gut biome testing as procedures and test methods may change slightly between batch runs.

An example of the level of detail seen in MG-rast is this before and after tree of the diversity in the genera of bacteria seen in Child 1 before and after the intervention.

Changes is color reflect changes in bacterial diversity

Research Question Answered!:

"Is raw, unmodified potato starch a "prebiotic?"

It is conclusive from the table above that raw potato starch acted as a prebiotic in all of the test subjects. As the standard definition of a prebiotic is that it "increases bifidobacteria and other bacteria known to convey health benefits," the answer is clearly, "Yes."

Future Research:

All good studies end in a call for more research. It's what keeps the research industry alive!

Researchers now need to determine if potato starch is a superior or inferior prebiotic as compared to others, and what the optimal dose should be. There should also be studies on complimentary fibers to increase the prebiotic effects of potato starch.


A healthy, fiber-filled diet is paramount to a robust immune system and great health. As a prebiotic supplement, potato starch can play an important role in maintaining healthy levels of beneficial gut microbes. When selecting a prebiotic supplement, do not overlook potato starch. A range of 1-4TBS per day has been shown to have a prebiotic effect and should be used as a rough guide when deciding how much to use. It may be wise to start with a smaller dose and increase weekly. Studies suggest that amounts greater than 4TBS per day will not be assimilated by intestinal bacteria.

Monday, December 8, 2014

More AmGut Reports!

Not sure how many around here remember Allan and his family project.  Last year around this time, a blog regular, Allan, got the wild idea to subject his entire family (wife and 2 kids) to an experiment based on my American Gut report. 

His plan was to have each family member get a 'before' report from AmGut, then add a different amount of potato starch to each diet, and get an 'after' report. 

The problem was it would be expensive, nearly $800.  So he launched an Indiegogo campaign to raise the money.  I was so excited about this project, that I secretly told Allan I would make up the difference.  Around Christmas last year, days before the campaign was about to expire, and still about $600 short, I sheepishly told Jackie what I was up to.  She rolled her eyes.  But then, Christmas miracle, supporters came in left and right and Allan ended up with over $1000 to fund his project!  See the full Indiegogo page here.

Results are now in!