Review of the plant-based nutrition and lifestyle medicine news January 2025

The start of the year often coincides with new resolutions to improve health, be it participating in Veganuary, Dry January or going back to an activity that brings you joy.

Photo by Jannis Brandt on Unsplash

Healthspan versus lifespan

This cross-sectional study examined the disparity between life expectancy (lifespan) and health-adjusted life expectancy (healthspan) among 183 World Health Organization member states, highlighting the years people live with disease or disability globally. The results showed that globally, in the last two decades, life expectancy increased by 6.5 years, whereas health-adjusted life expectancy only grew by 5.4 years, leading to a widening healthspan-lifespan gap, now averaging 9.6 years. This gap reflects the burden of diseases as people live longer but with more years in poor health. Women have a larger healthspan-lifespan gap than men, averaging 2.4 years more. The largest gaps are observed in high-income countries such as the United States (12.4 years), Australia (12.1 years), New Zealand (11.8 years), the UK (11.3 years) and Norway (11.2 years). The healthspan-lifespan gap strongly correlates with the prevalence of noncommunicable diseases (NCDs), such as musculoskeletal disorders, mental health issues, and chronic illnesses. The gap is inversely related to mortality; lower mortality results in survivors living longer with chronic conditions.

The study highlights the urgent need for health systems to shift focus from merely increasing lifespan to improving healthspan. This involves prioritising preventive care and addressing the burden of chronic diseases, with tailored interventions based on country-specific profiles. For me the solutions are clear. Healthy lifestyle habits need to be accessible and affordable to all since we know this approach promotes health and longevity. Read this review on the evidence support lifestyle medicine for improving health and wellbeing.

The best diets of 2025

When it comes to ‘adding years to life and life to years’ (in the words of Dr David Katz), dietary factors are key. We know that diets associated with both healthspan and lifespan are ones that is fibre-rich, prioritises plant sources of protein over animal sources (beans, lentils, pulses, nuts, seeds, soya), minimises/avoids ultra processed foods, especially processes meats, sugar-sweetened beverages, cakes/pastries/fried foods, and minimises/avoids red/processed meat. This is otherwise known as a plant-predominant, plant-rich, plant-forward or plant-based diet (so many names!). There are several ways of composing such as diet that can include cultural and traditional norms.

Each year, the US News and World report provide a list of the best diets for health. This year a panel of leading experts rated 38 diets across 21 categories focused on health conditions and lifestyle needs. Diets are rated on 'nutritional completeness, health risks and benefits, long-term sustainability and evidence-based effectiveness'. This year, once again, all top-rated diet patterns emphasised whole plant foods. For the 8th year in a row, the Mediterranean diet pattern came out top for overall best diet. The DASH, MIND and flexitarian diets do well in all categories. The Ornish diet, which is a low-fat whole food plant-based diet, came 6th overall and 8th for heart health (having previously been the top heart healthy diet in 2022). A vegan diet ranks 7th overall, 4th for heart health, 3rd for fatty liver and 2nd for cholesterol-lowering and gut health, losing points for being more difficult to follow and at risk of nutrient deficiencies. Those of us that follow a vegan diet know full well that it can be sustainable, enjoyable, full of abundance and can be adapted to all traditional diet patterns. Our own research demonstrates that a healthy vegan diet is sustainable and may be associated with numerous health benefits. But the overall message for 2025 is to eat more plants.

It is interesting to look back at the start of 2024 when ‘You Are What You Eat’ landed on Netflix on January 1st. It documented the intervention study in identical twins, who were randomised to a healthy vegan or a healthy omnivorous study. The results supported superior outcomes of a vegan diet, such that the authors concluded ‘the healthy vegan diet led to improved cardiometabolic outcomes compared with a healthy omnivorous diet. Clinicians can consider this dietary approach as a healthy alternative for their patients’. I remain confident in recommending a healthy vegan diet as a great option for my patients.

Alcohol and cancer:

It is timely to start 2025 with a US Surgeon General’s Advisory on alcohol and cancer risk. Advisories ‘are reserved for significant public health challenges that require the nation’s immediate awareness and action’. Alcohol consumption is a significant, preventable cause of cancer in the United States, contributing to nearly 100,000 cancer cases and about 20,000 cancer deaths annually. Globally in 2020, 731,000 cancer cases were attributable to alcohol. The advisory makes the following key points:

• Established Link to Multiple Cancers: Alcohol use is causally linked to increased risks of at least seven types of cancer: breast (in women), colorectal, oesophageal, liver, oral cavity, pharyngeal (throat), and laryngeal (voice box).

• Dose-Response Relationship: The risk of cancer escalates with higher alcohol consumption. Notably, for certain cancers like breast, mouth, and throat, the risk may begin to increase with consumption of one or fewer drinks per day.

• Public Awareness Gap: Despite the established risks, less than half of U.S. adults are aware of the connection between alcohol use and cancer. This lack of awareness underscores the need for enhanced public education.

• Mechanisms of Carcinogenesis: Alcohol can lead to cancer through several biological pathways. This includes the generation of the harmful metabolite acetaldehyde, that damages DNA. The generation of reactive oxygen species, which increase inflammation and can damage DNA, proteins, and lipids in the body through a process called oxidation. Alteration of hormones levels such as increased oestrogen levels, which increases the risk of breast cancer. Alcohol makes it easier for other cancer-causing agents to enter the cells, especially particles of tobacco smoke.

Deaths related to alcohol continue to rise in the UK as highlighted by the Governments own figures at the end of 2024. There were more than 8200 deaths in England and 1277 deaths in Scotland from alcohol.

The key message for 2025 is that there is no safe limit of alcohol to consume, especially when it comes to cancer risk. Healthcare professionals need to be clear that zero is the safest amount. You can read my recent blog piece here.

Healthy Lifestyle Care vs Guideline-Based Care for Low Back Pain

The study involved 346 participants in Australia with activity-limiting low back pain and at least one lifestyle risk factor. The intervention in the Healthy Lifestyle Program (HeLP) integrated guideline-based care with additional healthy lifestyle support. The aim was to assess the impact of lifestyle change with traditional low back pain management, focusing on modifiable risks such as overweight/obesity, poor diet, physical inactivity, and smoking. The intervention encouraged patients to take an active role in self-managing their condition through education and tailored coaching.

Guideline-Based Care involved standard physiotherapy consultations based on evidence-based recommendations for managing low back pain. This included pain education, advice, and exercise tailored to individual needs. The lifestyle-specific components included physiotherapy sessions, up to 4 sessions over 12 weeks. These focused on changing beliefs about pain, introducing the role of lifestyle in managing pain, and creating personalised self-management plans targeting lifestyle risk factors. There was also one dietitian consultation focusing on improving diet quality, specific advice on weight management and addressing alcohol consumption where relevant. A comprehensive booklet and web portal provided interactive educational content on pain management and healthy lifestyle habits such as nutrition, physical activity, and smoking cessation. Telephone-based health coaching was provided, up to 10 tailored coaching calls over 6 months. This focused on supporting weight loss, improving diet, and increasing physical activity. Smokers were offered additional support. Motivational interviewing and cognitive behavioural therapy (CBT) strategies were employed during consultations. There was also use of a visual communication and decision-making aid to systematically introduce and discuss lifestyle goals. Training was also provided for physiotherapists and health coaches.

The study showed the that the HeLP group had a statistically significant but modest improvement in disability at 26 weeks, measured by the Roland Morris Disability Questionnaire (mean difference of -1.3 points; 95% CI, -2.5 to -0.2; p = 0.03). Participants in the HeLP group also experienced small but significant improvements in weight loss (-1.6 kg; p = 0.049) and physical quality of life (p = 0.04). No significant differences were observed in pain intensity, smoking cessation, or mental quality of life. Among participants who adhered to the intervention (attending at least two consultations and five coaching calls), clinically meaningful improvements in disability and quality of life were observed. The intervention was safe, with no significant differences in adverse events between groups.

Overall, the study demonstrates that integrating healthy lifestyle care into guideline-based physiotherapy provided modest benefits in disability, weight management, and quality of life for patients with chronic low back pain. This approach could also address broader chronic disease risks. However, further research is needed to explore long-term effects, implementation strategies, and cost-effectiveness.

Online lifestyle therapy versus psychotherapy for reducing depression

The paper evaluates the CALM trial, a non-inferiority randomised controlled trial, comparing remote-delivered lifestyle therapy with psychotherapy (Cognitive Behavioural Therapy - CBT) for managing depression over an 8 week period. The aim of the study was to test whether lifestyle therapy (targeting nutrition and physical activity) is as effective as CBT for reducing depression when delivered online.

The study included 182 adults with depressive symptoms, measured by the Distress Questionnaire-5 (DQ-5). Participants were randomly assigned to two groups: Lifestyle therapy (n = 91) or Psychotherapy (CBT) (n = 91). Both received six 90-minute group sessions via videoconferencing over eight weeks. Outcomes were measured using the Patient Health Questionnaire-9 (PHQ-9) and cost analyses.

The lifestyle therapy developed by dietitians and exercise physiologists. It personalised goals targeting nutrition (e.g., improving diet quality and adherence to a Mediterranean-style diet), physical activity (e.g., increasing movement and structured exercise), sleep hygiene and substance use reduction (if applicable). Sessions included motivational interviewing, goal setting, and mindfulness strategies. Participants were provided with a hamper of healthy food items and TheraBand and Fitbit to encourage physical activity. The intervention was facilitated by accredited dietitians and exercise physiologists trained in mental health first aid.

Psychotherapy (CBT) was based on a structured group CBT manual. It targeted cognitive and behavioural patterns maintaining depression. It included mindfulness exercises and practical self-management strategies and homework activities focused on challenging negative thoughts and behaviours. This was facilitated by registered psychologists and trained assistants. Participants received mindfulness apps and stress-relieving tools.

The results showed that both interventions significantly improved depression scores. Lifestyle therapy was non-inferior to CBT, with no meaningful differences in primary or secondary outcomes. Cost analyses indicated marginally lower costs for lifestyle therapy.

The study demonstrated that lifestyle therapy delivered remotely is as effective and cost-efficient as CBT for reducing depressive symptoms. This suggests that trained allied health professionals (e.g., dietitians, exercise physiologists) can provide scalable, remote mental health care comparable to psychologists.

Loneliness and the risk of dementia

This meta-analysis investigates the association between loneliness and the risk of dementia using longitudinal data from over 600,000 individuals across 21 studies. The findings highlight that loneliness significantly increases the risk for all-cause dementia (31%), Alzheimer’s disease (39%), vascular dementia (74%), and cognitive impairment (15%). The study reveals that these associations persist even when controlling for factors like depression and social isolation. The heterogeneity in results is attributed to differences in loneliness measures and cognitive assessment methods.

The study underscores the importance of exploring the specific types of loneliness and cognitive symptoms to develop targeted interventions for reducing dementia risk. It also identifies gaps in current research, such as the need for more data from low- and middle-income countries and assessments of long-term loneliness effects. The findings emphasise the need to address loneliness through social and clinical strategies as part of dementia prevention efforts.

The latests output from the Lancet Commission on Dementia finds that 45% of dementia cases could be prevented. Read more about lifestyle approaches for supporting brain health in this article.

Gut health in vegan, vegetarians and omnivores

This study investigated the relationship between self-reported diet patterns and gut microbiome composition, analysing data from a large global cohort of 21,561 individuals. The three diet patterns examined, vegan, vegetarian and omnivore, significantly influenced gut microbial composition. In total, stool sample analysis from 656 vegans, 1,088 vegetarians and 19,817 omnivores was included.

The microbiome signature in omnivores was consistent with eating meat and included bacterial species such as A. putredinis, B. wadsworthia and R. torques, that have previously been implicated in inflammatory diseases such as inflammatory bowel disease, colorectal cancer, and are more likely to be associated with negative cardiometabolic health outcomes. Omnivores consumed fewer plant-based foods on average compared to vegetarians and vegans, resulting in lower abundance of fibre-degrading and short chain fatty acid (SFCA)-producing microbes. The lack of plant diversity contributed to reduced gut microbial richness and functionality compared to plant-based diets. Microbial functions in omnivores focused on protein and amino acid metabolism, reflecting the animal-product-heavy diet. Metabolic pathways for processing red meat and dairy products, such as the production of TMAO (trimethylamine N-oxide), were prominent in omnivorous microbiomes and are linked to inflammation and cardiovascular risk.

Vegetarians exhibited gut microbiomes enriched with microbes associated with moderate plant-based diets, such as Streptococcus thermophilus and Lactobacillus acidophilus, common in dairy products. The microbial signatures of vegetarians were linked to better cardiometabolic health outcomes than those of omnivores but not as favourable as vegans. While vegetarians consumed more plant-based foods than omnivores, their diets included fewer diverse plant sources compared to vegans, reflected in their microbial composition.

Vegans exhibited unique gut microbial compositions dominated by fibre-degrading bacteria such as Lachnospiraceae, Roseburia hominis, and Butyricicoccus sp. These microbes are linked to the production of SCFAs, which support gut health and reduce inflammation. Vegan-associated microbes showed a stronger correlation with favourable cardiometabolic health outcomes compared to omnivores and vegetarians. Signature microbes in vegans are linked to lower risks of inflammatory diseases, such as cardiovascular diseases and type 2 diabetes. Vegan diets, rich in diverse plant-based foods, resulted in higher health-promoting gut microbial diversity. Specific microbial functions enriched in vegans included fermentation of dietary fibers and biosynthesis of vitamins like vitamin B7 (inositol). Vegan gut microbiomes showed significant overlap with soil and plant microbiomes, including microbes like Enterobacter hormaechei and Klebsiella pneumoniae, which are often involved in plant growth and nitrogen fixation. These findings suggest dietary sources, particularly fruits and vegetables, contribute directly to gut microbial diversity in vegans.

Overall, the results confirm prior data that dietary patterns impact gut microbiome composition. That plant-based diets, especially vegan diets, are associated with greater gut microbial diversity and characterised by bacterial species that are associated with improved gut health, lower levels of inflammation and better cardiometabolic health. Increasing plant diversity in all diet patterns, including omnivorous diets, can foster beneficial microbial profiles. The finding that vegans have gut microbiomes that are found in plants and soil is intriguing and is an area that requires more research. You can read the study summary from the research team here.

There remain concerns around vegan diets for older adults, especially when it comes to muscle protein synthesis. This new study is a useful addition to the literature, albeit short and small. In a randomised, controlled, cross-over study of 34 community-dwelling adults with a median age of 72 years, a vegan diet for 10 days did not compromise muscle protein synthesis compared to an omnivorous diet. Of note, the participants were physically active, achieving 12,460 +/-4512 steps/day.

Planetary health diet, cardiovascular diseases and all-cause mortality

This systematic review and meta-analysis investigated the health impacts of adhering to the EAT-Lancet planetary health diet. 28 studies with over 2.21 million participants were included with most data coming from European countries, with notable research gaps in regions like Africa, Asia, and South America. The results showed that adherence to the PHD was associated with significant reductions in a number of health outcomes. This included a 22% lower risk of type 2 diabetes, 16% and 17% reduction in cardiovascular disease incidence and mortality, respectively, a 14% reduction in cancer incidence and mortality, and a 17% reduction in all-cause mortality. The study reinforces the health benefits of adopting the EAT-Lancet diet, supporting its potential to reduce the global burden of major chronic diseases and mortality. It highlights the need for region-specific studies and validation of diet scoring systems to expand global applicability.

There have been a number of criticism of the Eat-Lancet PHD, mainly due to potential shortfall in certain nutrients. This excellent viewpoint addresses these and makes recommendations for future work. We look forward to the Eat-Lancet 2.0 report later this year which will include more analysis and information on regional diets.

Other studies that caught my attention this month include an analysis of the burden of disease related to the consumption of sugar-sweetened beverages (SSBs) in 184 countries. In 2020, 2.2 million new cases of type 2 diabetes and 1.2 million new cases of cardiovascular disease were attributable to SSBs worldwide, representing 9.8% and 3.1%, respectively, of all incident cases. Pretty shocking. A systematic review of the impact of plant-based diets in people with Rheumatoid arthritis (RA) was published in Dec 2024. It included 15 studies that assessed the impact of a plant-based diet in its loose term (a diet pattern that is predominantly centred around whole plant foods). Seven the of 15 studies were based around the Mediterranean diet. Studies that investigated vegan or whole food plant-based diets were also part of the analysis, including studies from the Plants for Joints team and Dr Neal Barnard. Overall the study concluded that a plant-based diet is beneficial in people with RA, especially the Mediterranean diet, which has been most extensively studied.