GUT MICROBIOTA AND NUTRITION NEWSLETTER #18
May, 2020
Hello, all! We hope you are staying healthy and safe according to your conditions and recommendations locally.
For dietitians who receive questions from clients about probiotics, it's important to know that April brought important changes to Lactobacillus taxonomy--meaning that some common probiotic species have new names. Read more below, and see this website where you can look up the old and new names of the re-classified bacteria.
Personalized nutrition is the theme of several other items in this newsletter: a summary of where the science on gut microbiota and diet stands; a review focusing on gut microbiome tests and their associated dietary recommendations; and finally, a ‘practice tip’ on how dietitians can gear up for a future of digital tools that are incorporated into clinical practice and allow for increasingly tailored diets.
Natasha and Kristina
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Your guide to new probiotic names: Lactobacillus
Last month, scientists announced name changes for some bacteria in the genus Lactobacillus, including some important probiotic species. The name changes were necessary in order to re-group the diverse bacteria in this genus according to their genetic similarities, and to adhere to the naming conventions for all living things. See here for an overview of these name changes and what they mean.
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COVID-19: is there a role for immunonutrition, particularly in the over 65s?
The relationship between nutrition and COVID-19 disease is a hot topic at present: can diet be used for 'prehabilitation' -- for example, taking steps to protect older adults, who typically have less immune competence? This review in BMJ Nutrition summarizes how the immune system can be altered by diet to protect against viral infections. (For more detail, see this review of evidence on micronutrients and the immune system.) The authors consider this a good time to take a closer look at the diets of older adults (particularly intake of vitamins C, D, and zinc) to see how it might be improved.
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Food and nutrition are critical to the current and post-COVID-19 response
Food has been a major topic of conversation during the COVID-19 pandemic, and many important questions have been raised: What dietary changes are people experiencing during lockdown? Has food security in some households decreased? This infographic from Tufts University shows 9 areas in which food and nutrition are relevant during the COVID-19 pandemic and beyond. Addressing each area is part of a “moonshoot” to prevent disease and save lives by improving the entire food system.
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Impact of dietary intake of resistant starch on obesity and associated metabolic profiles in human: a systematic review of the literature
What health benefits can be expected from the consumption of resistant starch (RS)? Researchers are looking at whether these benefits could come about through the gut microbiota, and to date, the studies are not conclusive but some evidence exists for modest benefits. This systematic review looked specifically at the impact of RS on obesity and metabolic parameters in humans. RS appears to have no direct effect on body weight, but likely has a positive effect on blood glucose levels, insulin sensitivity, and several other metabolic parameters.
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Microbiome quick guides series: Metabolites
New in the ‘microbiome quick guides’ series, this blog post describes what metabolites are, how they’re measured, and how they can act as ‘messengers’ between the gut microbiota and human cells.
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Current explorations of nutrition and the gut microbiome: a comprehensive evaluation of the review literature
If you want a nice introduction to the science that’s been done on nutrition and gut microbiome in healthy adults, see this review written by Leigh Frame, Elise Costa, and Scott Jackson. Most of the work to date focuses on dietary fiber, which is described here as 'microbiota fuel'. Protein, on the other hand, produces potentially harmful byproducts via the microbiota. Undoubtedly, nutrition affects gut microbiota composition and various processes necessary for good health. Looking ahead to how the gut microbiota will play a role in nutritional personalization, the authors say more science is needed on individual responses to diet.
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Treating the individual with diet: is gut microbiome testing the answer?
By now you may have seen information from multiple companies that claim to give personalized dietary advice based on analysis of a gut microbiome (stool) sample. The tests are based on the logic that, if diet shapes the gut microbiome, a specific diet can shape the gut microbiota in a desired way, leading to better health. A new scientific review (and this news summary from the authors) gives an overview of gut microbiome testing and dietary advice -- concluding that, while personalizing diet is a worthy goal, gut microbiome tests are not reliable ways of doing so at present. See the practice tip below for further discussion of personalized nutrition.
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Practice Tip: The 'why' and 'how' of evaluating personalized nutrition tools
Dietitians are adept at personalizing dietary recommendations according to many client factors, including demographic group, anthropometric measurements, and preferences. But it seems that in not-too-distant future, it may be possible to personalize recommendations even further. Digital tools will be one way to do this, and in a perfect world they would take complex data about a client, using machine learning algorithms to generate recommendations that lead to better health. Several digital tools already exist on the market for consumers: for instance, gut microbiome tests that generate very specific lists of what a person should eat and avoid.
When most of these tools are marketed to consumers, is it necessary for dietitians to prepare for a future of clinical practice that integrates these tools? And as more and more digital ‘solutions’ emerge, how can dietitians know which tools are based on good science?
Two recent review papers are immensely helpful in framing these personalized nutrition tools, along with how they can become a part of clinical practice and of healthcare service delivery on a population level.
First, a paper from Journal of the Academy of Nutrition and Dietetics defines personalized nutrition tools as those that, ‘use individual-specific information, founded on evidence-based science, to promote dietary behaviour change that may result in measurable health benefit’. The paper summarizes the discussion of a multidisciplinary expert panel that met to develop guiding principles for personalized nutrition approaches in dietetics practice. The experts urged dietitians to think critically about using these platforms, and developed 10 guiding principles that should apply to new tools:
- Define potential users and beneficiaries
- Use validated diagnostic methods and measures
- Maintain data quality and relevance
- Derive data-driven recommendations from validated models and algorithms
- Design personalised nutrition studies around validated individual health or function needs and outcomes
- Provide rigorous scientific evidence for an effect on health or function
- Deliver user-friendly tools
- For healthy individuals, align with population-based recommendations
- Communicate transparently about potential effects
- Protect individual data privacy and act responsibly
A second paper, in Journal of Human Nutrition and Dietetics, urges dietitians to start preparing now for a future of digital personalized nutrition. The authors argue, "dietitians have a unique opportunity to be a guiding voice, a reality check and a key resource for the creation and delivery of new solutions and healthcare models." The paper urges dietitians to become more tech-focused and learn about digital tools and approaches as much as possible, in order to be a touchstone for clients who want reliable information about whether such tools will deliver on their promise to improve health.
A final note: when it comes to microbiome-focused solutions, the science still has a long way to go. So far, none of the tools available to consumers have extensive scientific validation (see the review article described above). We remain hopeful, however, that someday approaches that include gut microbiota data will be an excellent way to tailor clients' diets for better health. We'll continue to track the approaches of these gut microbiome tests and the science that backs them, and share new developments with you here.
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