|
Research Roundup
Issue No. 1 · March 24th, 2026
|
|
|
Brought to you by the FNL
Every study in this newsletter is already organized and waiting for you inside the library, searchable by condition, nutrient, special diet, and more. No inbox archaeology required.
|
|
|
Welcome to Issue No. 1 of the FNL Research Roundup!
We scan the latest functional nutrition research and pull the studies most relevant to clinical practice, so you don't have to.
Inside each issue, you'll find our plain-language takeaways and an honest note on limitations, because we think good research literacy means knowing what the evidence can (and can't) tell us.
All the studies mentioned here are also integrated into the notes inside the FNL membership. Searchable, continuously updated, and ready for the moment you need it in a session. We're glad you're here!
|
|
|
Gut Health & The Microbiome |
|
|
THE CROHN'S DISEASE EXCLUSION DIET: WHAT DOES THE EVIDENCE ACTUALLY SAY? Scoping Review | Nutrition Reviews | 23 studies | Adults with Crohn's disease | Search through July 2025
RCTs show that the Crohn's Disease Exclusion Diet (CDED) matches exclusive enteral nutrition for remission induction while being significantly better tolerated. That said, substantial heterogeneity across study designs, dietary compositions, and outcome measures makes it difficult to draw clean conclusions across the board.
Practice: CDED is increasingly supported as a whole-food alternative to liquid-only enteral nutrition, particularly for patients who struggle with EEN adherence.
CAN GUT-SUPPORTIVE DIETARY PATTERNS LOWER HYPERTENSION RISK? Cross-Sectional Study | Hypertension | National survey data
This study examined whether dietary patterns known to support gut microbiota diversity are associated with lower hypertension risk. The findings suggest that people eating in ways that support a diverse microbiome tended to have 27% lower odds of developing hypertension.
Practice: Framing gut-supportive eating (high fiber, diverse plant foods, fermented foods) as cardiovascular-protective may resonate well for some clients.
Worth noting: Cross-sectional design means causality cannot be established. Dietary pattern data from surveys is also subject to recall bias and measurement error.
PROBIOTICS FOR IBS: PROMISING, BUT THE EVIDENCE ISN'T THERE YET Systematic Review & Meta-Analysis | Journal of Gastroenterology and Hepatology | 40 RCTs | 4,098 patients
This review goes a step further than most by asking not just whether probiotics work, but whether we have enough evidence to know. Probiotics showed statistically significant improvements in IBS symptom severity scores, but the required sample size of 11,386 patients hasn't been reached yet, meaning the cumulative evidence is still inconclusive. Multistrain formulations and courses of 8 weeks or more showed stronger effects.
Practice: If recommending probiotics for IBS, multistrain formulations and longer treatment durations have better support.
Worth noting: GRADE certainty of evidence was rated very low, primarily due to high heterogeneity. The American College of Gastroenterology still does not formally recommend probiotics for IBS.
BACILLUS SPORE PROBIOTICS FOR CHILDHOOD CONSTIPATION: A HIGH-QUALITY RCT Randomized Double-Blind Placebo-Controlled Trial | Communications Medicine | 111 children aged 24–60 months | Vietnam | 28 days
This well-designed RCT tested a multi-strain Bacillus spore probiotic formulation against placebo in preschool children with functional constipation. By day 28, the proportion of children meeting Rome IV criteria for constipation dropped 3.7-fold compared to a modest 1.25-fold decrease in placebo. Improvements were visible as early as day 7. Beyond bowel function, the probiotic group also showed improvements in appetite and weight gain, reduced pro-inflammatory cytokines (IL-6, IL-23), increased anti-inflammatory IL-10, a substantial rise in fecal IgA, and beneficial microbiome shifts.
Worth noting: The study was conducted in Vietnam in preschool-aged children, which may limit generalizability to other populations and age groups. One author is also a founder of the company that produces the probiotic products. Longer-term follow-up data are still needed.
|
|
|
HISTAMINE & FOOD SENSITIVITIES |
|
|
RETHINKING IBS: COULD DIAMINE OXIDASE DEFICIENCY BE THE MISSING PIECE? Review | Histamine Intolerance | 2026
This review suggests that diamine oxidase (DAO) deficiency (the enzyme responsible for breaking down histamine in the gut) may be an underdiagnosed driver of IBS-like symptoms. Symptoms of DAO deficiency overlap substantially with IBS, including bloating, diarrhea, abdominal pain, and altered motility.
Practice: For IBS patients who haven't responded to standard dietary interventions, histamine intolerance is worth adding to the differential. A low-histamine dietary trial or DAO enzyme supplementation may be worth exploring, particularly in patients with concurrent symptoms like headaches, skin flushing, or nasal congestion that don't fit a typical IBS picture.
Worth noting: The histamine intolerance literature is still developing, and diagnostic criteria are not yet standardized. DAO testing is available but not universally validated.
RESISTANCE EXERCISE TRIGGERS HISTAMINE RELEASE — WHAT DOES THAT MEAN FOR YOUR CLIENTS? Human Study | Journal of Applied Physiology | 12 participants | Trained athletes aged 18–35 | University of Oregon
This is the first study to document histamine release in response to resistance exercise (rather than just aerobic exercise).
Practice: For clients with suspected or confirmed histamine intolerance who experience post-exercise symptoms (like fatigue, flushing, headaches, GI distress, or nasal congestion) this study provides a plausible biological mechanism that applies to both cardio and strength training. For sensitive individuals, timing of low-histamine eating around exercise sessions, DAO enzyme support, and adequate recovery time may be worth exploring as part of a personalized management approach.
Worth noting: The sample was small, mostly male, and consisted entirely of trained athletes, which limits generalizability to general population clients. The link between exercise-induced histamine release and clinical symptoms in sensitive individuals remains to be directly studied.
|
|
|
NEURODEVELOPMENT & MENTAL HEALTH |
|
|
METABOLOMIC SIGNATURES IN CHILDREN WITH AUTISM SPECTRUM DISORDER FOLLOWING A KETOGENIC/GLUTEN-FREE DIET Observational/Biomarker Study | BMC Psychiatry | 7 children | Gluten-free modified ketogenic diet
This study used metabolomic profiling to examine plasma biomarker changes in children with autism spectrum disorder following a gluten-free modified ketogenic diet intervention. Distinct metabolic signatures were identified in ASD children at baseline, and meaningful shifts in those signatures were observed following the dietary intervention, suggesting the diet was producing measurable metabolic changes, alongside behavioral improvements.
Worth noting: Seven participants is a very small sample, and this is an observational study without a control group, so we cannot draw causal conclusions. Results are hypothesis-generating rather than practice-changing. Larger controlled trials are needed before specific dietary protocols can be formally recommended.
|
|
|
DIET & CARDIOVASCULAR HEALTH |
|
|
MEDITERRANEAN DIET VS. LOW-FAT DIET: THE EVIDENCE GETS CLEARER Systematic Review | Medicine | 11 RCTs | 5,942 participants
The Mediterranean diet outperformed the low-fat diet across multiple cardiovascular risk markers (total cholesterol, cholesterol-to-HDL ratios, insulin, blood glucose, inflammatory markers, and BMI.) The authors conclude the evidence supports Mediterranean over low-fat approaches for preventing cardiovascular disease and outcomes.
Practice: Adds RCT-level weight to a recommendation many functional nutrition practitioners are already making. Useful ammunition for clinical conversations where clients push back on dietary fat or remain attached to the low-fat paradigm.
HEALTHY LIFESTYLE ADHERENCE AND CARDIOMETABOLIC RISK IN HYPERTENSION Cohort Study | Hypertension | Large prospective cohort | Hypertensive adults
This large prospective cohort study found that high adherence to healthy lifestyle behaviors (high-quality diet, physical activity, no smoking, low alcohol consumption, and healthy BMI) reduces the risk of cardiovascular disease by 51% and the risk of type 2 diabetes by 79% in people already diagnosed with hypertension. People with hypertension who adhered to all 5 healthy lifestyle behaviors at age 40 were estimated to gain 8.2 additional years of life expectancy compared to those who only adhered to 0 or 1 behaviors.
Practice: This is powerful data to share with hypertensive clients who feel a diagnosis means the damage is already done. The cumulative effect finding is particularly helpful (each 1-unit increase in HLS was associated with a 10% lower CVD risk and 21% lower T2D risk), reinforcing that each additional healthy behavior matters, even if clients can't adopt all of them at once.
Worth noting: Cohort study design limits causal inference, and self-reported lifestyle data introduces measurement error.
|
|
|
AUTOIMMUNITY, DIAGNOSTICS & BONE HEALTH |
|
|
A NOVEL BIOMARKER APPROACH TO CELIAC DISEASE MONITORING Diagnostic Study | Turkish Journal of Gastroenterology
This study found that the systemic immune-inflammation index (SII) correlates meaningfully with celiac disease activity and can distinguish adults with CD from healthy counterparts with a sensitivity 86% and specificity of 90%.
Practice: For practitioners managing clients with celiac disease, this adds to the growing toolkit of inflammatory biomarkers worth tracking. The SII is calculated from a standard CBC (neutrophil count × platelet count/lymphocyte count), making it low-cost and widely accessible. It won't replace antibody testing or biopsy, but may be a useful adjunct for monitoring dietary adherence and inflammatory burden over time.
Worth noting: This is a single diagnostic study from one center, and the SII is not yet validated as a standalone celiac monitoring tool. Results need replication in larger, more diverse populations before clinical adoption can be recommended.
YOUR PATIENT'S LIPID PANEL MIGHT BE TELLING YOU MORE ABOUT THEIR BONES Cross-Sectional Study | Medicine | 6,149 US women | NHANES 2005–2018
This study found that in US women, having a non-HDL to HDL cholesterol ratio (NHHR) below 3.371 is associated with a lower rates of osteoporosis. (In other words, having higher HDL levels, relative to other types of cholesterol, is associated with reduced prevalence of osteoporosis.) NHHR is calculated from a standard lipid panel: (Total Cholesterol − HDL) ÷ HDL, making it a zero-cost data point most practitioners already have access to.
Practice: For postmenopausal women or those at elevated osteoporosis risk, NHHR is worth a second look when reviewing routine labs. It won't replace DXA scanning, but may serve as a useful additional signal.
Worth noting: Cross-sectional design means causality cannot be established. Findings are specific to US women and may not generalize to men or other populations. Treat as an emerging consideration rather than a practice-changing finding.
|
|
|
THIS month IN THE LIBRARY
Don't save this email. It's already in there.
Everything above (plus hundreds of other studies, best practices, and clinical resources) is organized, searchable, and continuously updated inside the membership.
Our newest notes:
→ Alpha-Gal Syndrome
→ Agave
+ All studies from today's roundup, integrated into the existing content
|
|
|
