by Marion Nestle

Currently browsing posts about: Fermented foods

Mar 18 2024

Industry-funded study of the week: Would you believe kimchi?

I learned about this one from a commentary from Yoni Freedhoff, MD: Kimchi: Not Magically Protective Against Weight Gain.

  • The study: Association between kimchi consumption and obesity based on BMI and abdominal obesity in Korean adults: a cross-sectional analysis of the Health Examinees study.  BMJ Open.  2024 Jan 30;14(2):e076650.  doi: 10.1136/bmjopen-2023-076650.
  • Participants: “This study analysed 115 726 participants aged 40-69 years enrolled in the Health Examinees study in Korea.”
  • Results: “In men, total kimchi consumption of 1-3 servings/day was related to a lower prevalence of obesity (OR: 0.875 in 1-2 servings/day and OR: 0.893 in 2-3 servings/day) compared with total kimchi consumption of <1 serving/day. Also, men with the highest baechu kimchi (cabbage kimchi) consumption had 10% lower odds of obesity and abdominal obesity. Participants who consumed kkakdugi (radish kimchi) ≥median were inversely associated with 8% in men and 11% in women with lower odds of abdominal obesity compared with non-consumers, respectively.”
  • Conclusions:  “This large cross-sectional study described the association between kimchi consumption and obesity. In conclusion, total kimchi consumption of 1–3 servings/day was shown to be reversely associated with obesity in men. Regarding the type of kimchi, baechu kimchi was associated with a lower prevalence of obesity in men, and kkakdugi was associated with a lower prevalence of abdominal obesity in both men and women. However, since all results showed a ‘J-shaped’ association, excessive consumption suggests the potential for an increase in obesity prevalence. As kimchi is one of the major sources of sodium intake, a moderate amount of kimchi should be recommended for the health benefits of its other components. In addition, further investigation and prospective studies are needed to confirm the relationship between kimchi consumption and obesity.”
  • Competing interests: “HJ and SS have no conflicts of interest to declare for this study. Y-RY and SWH are members of the staff at the World Institute of Kimchi.”
  • Funding: “This research was supported by grants from the World Institute of Kimchi (KE2201-1) funded by the Ministry of Science and ICT, Republic of Korea.”

Dr. Freedhoff ‘s analysis of the data:

According to the paper, men who reported eating two to three servings of kimchi per day were found to have lower rates of obesity, whereas men who reported eating three to five servings of kimchi per day were not. But these are overlapping groups! Also found was that men consuming more than five servings of kimchi per day have higher rates of obesity. When taken together, these findings do not demonstrate a statistically significant trend of kimchi intake on obesity in men. Whereas in women, things are worse in that the more kimchi reportedly consumed, the more obesity, in a trend that did (just) reach statistical significance.

Comment: Why anyone would expect kimchi (spicy fermented vegetables such as cabbage) to affect obesity one way or the other is beyond me, but the World Institute of Kimchi must want more people to eat it.  Does anyone need an excuse to eat kimchi?  It’s great on its own without needing this kind of claim.  This study is about marketing, not science.

Aug 14 2023

Industry-influenced study of the week: Kombucha

The study: Kombucha tea as an anti-hyperglycemic agent in humans with diabetes – a randomized controlled pilot investigation.  Mendelson Chagai, Sparkes Sabrina, Merenstein Daniel J., Christensen Chloe, Sharma Varun, Desale Sameer, Auchtung Jennifer M., Kok Car Reen, Hallen-Adams Heather E., Hutkins Robert.  Frontiers in Nutrition.  2023;10.  DOI=10.3389/fnut.2023.1190248.

Purpose: “Kombucha is a popular fermented tea that has attracted considerable attention due, in part, to its suggested health benefits. Previous results from animal models led us to hypothesize kombucha may reduce blood sugar levels in humans with diabetes. The objective of this pilot clinical study was to evaluate kombucha for its anti-hyperglycemic activities in adults with diabetes mellitus type II.”

Method: 12 study subjects were instructed to consume kombucha or a placebo (240 ml each) for 4 weeks, then later switch to the other one.

Results: “Kombucha lowered average fasting blood glucose levels at 4 weeks compared to baseline (164 vs. 116 mg/dL, p = 0.035), whereas the placebo did not (162 vs. 141 mg/dL, p = 0.078).”

Conclusion: “In this pilot study, the effect of kombucha consumption on blood glucose levels in adult T2D subjects revealed positive effects. Nonetheless, this study was not sufficiently powered to provide more definitive conclusions.”

Acknowledgment: “We thank Craft Kombucha, Kombucha Brewery in Washington, DC, and especially founder Tanya Maynigo-Loucks for donating the kombucha and for creating and donating the placebo drink for this study.”

Conflicts of interest: “RH is a co-founder of Synbiotic Health; JA has a financial interest in Synbiotic Health. DM serves as President of the Board of Directors of the International Scientific Association for Probiotics and Prebiotics, a non-paid position. All kombucha and placebo drinks were donated by Craft Kombucha. Craft Kombucha did not have any access to data reported in this study. No author has any financial ties with Craft Kombucha. SD was employed by MedStar Health. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Comment: Synbiotic Health develops and sells probiotic ingredients.  Its “mission is to harness the power of the human microbiome, using the best science to develop precise, scientifically validated microbiome ingredients that support optimal health in every age group.”  Craft Kombucha sells its products in classy cans.  Kombucha is a fermented sweet tea; it contains bacteria and yeast (probiotics).   It’s easy to find claims for its health benefits if you search for them, but much harder to find science to back them up.  IIf you can demonstrate benefits, you can sell more products.  Hence, this study.  High marks to the authors for including the disclaimer: “this study was not sufficiently powered to provide more definitive conclusions.”  Indeed.

My bottom line: drink kombucha if you like it, but don’t expect miracles.

Thanks to Laura Schmidt for this one.  Both of us like kombucha drinks, by the way.

Sep 24 2021

Weekend reading: Immunity, Covid-19, and Generally Good Health

A reader, Philly Nassau, sent me the ingredient list of several “immune-boosting” supplements, in quotes because I am a supplement skeptic in general, and of immune supplements in particular (I favor eating healthfully and staying active).

Immune supplements claim to be “Nootropics and Brain Supplement for Memory, Brain Support, Clarity, Focus, Mood Boost, Anti Anxiety & Stress Relief.”  Nootropics?  These are defined as drugs or supplements capable of enhancing memory, concentration, or other cognitive functions and of preventing cognitive decline.  How I wish.

But first, the science.

  • Gut-microbiota-targeted diets modulate human immune status.  “The data highlight how coupling dietary interventions to deep and longitudinal immune and microbiome profiling can provide individualized and population-wide insight. Fermented foods may be valuable in countering the decreased microbiome diversity and increased inflammation pervasive in industrialized society.”
  • The Stanford press release on this paper. A fermented-food diet increases microbiome diversity and lowers inflammation, Stanford study finds.  Stanford researchers discover that a 10-week diet high in fermented foods boosts microbiome diversity and improves immune responses.
  • The New York Times account: How Fermented Foods May Alter Your Microbiome and Improve Your Health.  Foods like yogurt, kimchi, sauerkraut and kombucha increased the diversity of gut microbes and led to lower levels of inflammation.

Beyond eating healthfully and including fermented foods in the diet, here’s what’s being said about diet and immunity.