As nutritional research continues to uncover the intricate links between diet and health, two recent studies shed light on the remarkable benefits of certain foods. A study from the University of Colorado delved into the metabolites of salmon, pinpointing compounds associated with improved heart health, while a review on fermented foods explored their potential impact on cognitive well-being through the intricate gut-brain axis.

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The compounds that make salmon good for you

Salmon, rich in omega 3 fatty acids, is frequently cited as a healthy dinner option, which has been further supported by a recent study conducted by scientists at the University of Colorado Anschutz Medical Campus. Delving into the biological components of salmon through metabolomics, a field focusing on tiny molecules resulting from metabolism, the study, which was reported in the article “Why is Salmon Good for You? Researchers Discover the Compounds that Make the Fish so Healthy” by Healthline, aimed to identify specific metabolites derived from salmon and correlate them with potential health benefits.

Participants adhered to a controlled Mediterranean diet that included two servings of salmon per week as well as heart-healthy foods; centring on vegetables, fish, and whole grains. Scientists identified 508 compounds specific to salmon, linking them to blood samples from participants. Only 48 of these salmon-specific metabolites increased in blood tests during the Mediterranean diet, mainly comprising fats, reaffirming the health benefits of omega-3 and polyunsaturated fatty acids in salmon.

The study found that increases in two salmon-specific compounds and two metabolites were associated with short-term improvements in cardiometabolic health indicators, including lower total cholesterol, LDL cholesterol, blood triglycerides, and ApoB, an indicator of heart disease. While the study delves into the scientific realm of metabolomics, the practical benefits of salmon are clear. The tasty fish is rich in protein, omega-3 fatty acids, B vitamins, potassium, and selenium.

What the study highlights specifically is not only how salmon can support health, heart health in particular, but also how easy it is to include it in our diet. Ultimately, this study adds depth to the understanding of salmon's health benefits, reinforcing its status as a nutrient-rich food source that is well worth including in a heart-healthy diet.

The link between fermented foods and mental health

In recent years, the spotlight on gut health in the media has intensified, with a particular focus on gut-brain axis. A review that was recently discussed in the article “Could eating more fermented foods help improve mental health?” by Medical News Today delves into the impact of fermented foods on this axis, exploring various types of fermented foods, fermentation techniques, and their influence on cognitive health.

The review emphasises that fermented foods, such as kimchi, sauerkraut, kefir, miso, tempeh, and yoghurt, have a direct impact on the enteroendocrine system, affecting hormones including ghrelin, neuropeptide-Y, glucagon-like peptide 1 (GLP-1), and serotonin. Rich in prebiotics and probiotics, fermented foods increase the production of GLP-1, however further research is required to better understand their impact on appetite and hunger.

While studies on fermented dairy have yielded mixed results regarding cognitive health, observational studies link fermented food intake with changes in gut health and reduced anxiety. The review builds on existing research into the gut-brain axis, linking diet to brain health through the microbiota.

Dr. Nicole Avena, a nutrition consultant and assistant professor of neuroscience, commends the review for presenting the history and physiology behind fermentation, establishing it as a superfood for gut and brain health. Explaining the gut-brain link, Avena highlights the uniqueness of each person's microbiome and the role of food in diversifying and strengthening gut flora, impacting mental and brain health.

The gut-brain connection involves intricate pathways via nerves and circulation. Substances produced in the gut can send signals to the brain, influencing mood, behaviour, memory, and cognition. Conversely, substances from the brain can impact the gut microbiome. Dysbiosis, an abnormal gut microbiome composition, is associated with various neurodegenerative disorders.

Fermented foods support the gut bacteria ecosystem by providing bioactives, healthy bacteria, and metabolites. This contributes to the activation of brain pathways, influencing mood and behaviour. However, further research is needed into this link as the current research has limitations, such as the generalisation of findings across regions and the diversity of factors influencing the gut-brain axis. Despite these challenges, the review builds a compelling case for the impact of gut health on brain health, affecting mood and behaviour in particular.

New research shows seasonality effect on vitamin D levels

A recent study challenges the previously widely accepted notion that rampant vitamin D deficiencies during the Industrial Revolution were primarily caused by factors such as factory work and polluted urban environments. The research, funded by Marsden and published in PLOS One and discussed in the article “Uncovering the hidden causes of rickets: Vitamin D deficiency in industrial England”, focuses on individuals from an industrial-era cemetery site in England. Dr. Annie Sohler-Snoddy, the lead author and Research Fellow in Otago’s Department of Anatomy, employed innovative bioarchaeological methods to investigate the root causes of vitamin D deficiencies.

Contrary to assumptions linking deficiencies to indoor work, crowded housing, and smog-filled environments, the study examined teeth from the archaeological site, identifying microscopic markers of nutritional disease. The findings unveil some of the first clear evidence of seasonal vitamin D deficiency in an archaeological sample. The research challenges conventional theories, emphasising that latitude and seasonal sunlight significantly impact vitamin D levels in individuals residing in northern England.

Dr. Sohler-Snoddy stresses the complexity of the issue, stating, “It’s more complicated than the factors associated with the Industrial Revolution, like working indoors more.” The study discovered markers of vitamin D deficiency in 76% of the teeth analysed, showcasing evidence of seasonal variations in vitamin D levels. This groundbreaking revelation underscores the role of latitude and sunlight in vitamin D production.

The research expands the understanding of rickets during the Industrial Revolution, shifting the focus from lifestyle factors to the impact of geographical location and changing seasons on vitamin D levels. Vitamin D deficiency is linked to various health issues, including infectious diseases, cardiovascular problems, and cancers. Dr. Sohler-Snoddy emphasises the importance of studying historical cases to inform modern approaches, highlighting the consistent biology over the last 200 years and the valuable insights teeth provide in understanding historical factors influencing health. The study bolsters the growing body of research regarding the importance of vitamin D and how to counteract deficiency.

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Alison Astill-Smith author Alison is Director and Founder of Metabolics who writes about Metabolics updates, events and natural healthcare. Her experience and passion for natural supplements and healthcare comes from her years of experience as a practising osteopath, having founded Metabolics in her search for high quality, natural products in her own work. Alison has been a qualified and practising Osteopath since 1981 and regularly gives seminars on a range of healthcare subjects to the wider practitioner community helping share her knowledge and experience.