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

This month I cover stalling life expectancy, nature versus nurture, cancer, psoriasis, depression and a reminder that butter is NOT back!

Life expectancy growth stalls in Europe.

This study examines changes in life expectancy in European countries, including the UK, from 1990 to 2021, using data from the Global Burden of Disease Study 2021. The research identifies three key periods: 1990–2011 (steady improvement in life expectancy), 2011–2019 (a slowdown in improvement), and 2019–2021 (a decline due to the COVID-19 pandemic). In the UK, life expectancy improved at a rate of 0.25 years per year from 1990 to 2011 but slowed to 0.07 years per year between 2011 and 2019. The slowdown was attributed to reduced progress in reducing deaths from cardiovascular diseases and cancers.

Between 2019 and 2021, life expectancy declined across most European countries, with the UK experiencing some of the largest reductions. In England, life expectancy fell by an average of 0.6 years annually during this period, largely due to COVID-19-related deaths and respiratory infections. There are notable exceptions with Norway, Iceland, Sweden, Denmark and Belgium continuing to make progress after 2011. These countries (except Belgium) also maintained improvements in life expectancy in 2019–21 during the COVID-19 pandemic, when life expectancy decreased in all other countries except Ireland. These country differences appear to be due to continued reduction in deaths from cardiovascular diseases and cancer, from long-term policy interventions that address risk factor modification.

The research highlights key risk factors contributing to life expectancy trends in the UK, including high blood pressure, dietary risks, high LDL-cholesterol, high BMI, and tobacco use. While smoking rates declined, the prevalence of obesity and poor dietary habits increased, counteracting gains in cardiovascular health. The study suggests that government policies and public health interventions play a crucial role in shaping life expectancy trends. Countries that maintained reductions in major health risks, mainly due to risk factor modification, tended to show better resilience to health crises like the COVID-19 pandemic. The findings emphasise the need for stronger policies to address obesity, dietary risks, and physical inactivity to prevent further stagnation or decline in life expectancy. The authors also note that their findings do not support the hypothesis that the slowing of life expectancy improvements is because a natural longevity ceiling has been reached at around 110 years of age. This is because life expectancy is driven by changes in mortality below 100 years, where there remains scope for significant improvement through risk factor modification.

It’s worth mentioning that the BMJ this week provides an editorial on the topic UK mortality rates and raises the fact that the study discussed along with a recent BBC article fails to acknowledge the impact of the austerity programme. Austerity as a Government policy introduced in 2010 led to cuts to social security benefits and public services, disproportionately affecting the most vulnerable in society. This led to worsening of health inequalities with mortality rates increasing more in areas with greater socioeconomic deprivation. A reminder of the importance of social determinants of health and that economic policies also significantly impact health outcomes.

Nature versus nurture

This new study answers the age old question as to whether genetics or environmental exposures contribute most to health outcomes The study used rather complex methodology to analyse data from participants of the 492,567 UK Biobank study. Researchers identified 25 independent environmental exposures associated with both mortality and biological aging. These exposures were also associated with major age-related diseases, biomarkers, and risk factors. Th environmental exposures were then correlated with polygenetic risk scores for 22 major diseases.

The analysis found that genetics factors contributed less than 2% of the risk of developing serious diseases. In contrast, environmental factors explained 17% of the risk of these chronic conditions. Genetic factors contributed more to dementia and certain cancers (10-26%), whereas environmental exposures played a greater role in lung, heart, and liver diseases (5.5-49%).

The environmental factors having the most negative impact on ageing were smoking, socioeconomic deprivation, physicial inactivity and living conditions. Other negative factors included low household income, unemployment, experiencing financial difficulty in the past two years, short sleep duration (<7 hours per day), living alone (without a partner), maternal smoking around birth and greater body size at 10 years old

This is one of many studies that demonstrate the impact of lifestyle and environmental factors on health and longevity. For example, last year I covered a study from the Million Veteran Program that showed that lifestyle factors were responsible for 64% of the risk of premature death. These studies reiterate the enormous potential we have to prevent chronic ill health by addressing both socioeconomic and lifestyle determinants of health.

Dietary patterns and colorectal cancer risk

Colorectal cancer (CRC) is soon be the leading cause of cancer death in people under that age of 50 years. Yet, this is one of the cancers that can benefit hugely from adopting healthy habits, with dietary factors being key.

This systematic literature review conducted as part of the Global Cancer Update Programme (CUP Global) examines the association between dietary patterns and colorectal cancer (CRC) risk. This updated review includes data from randomised controlled trials and prospective cohort studies published up to March 2023. The analysis categorises dietary patterns based on derivation methods— a priori (predefined dietary guidelines), a posteriori (data-driven approaches), and hybrid methods— and assesses their impact on CRC risk and mortality.

The findings indicate that adherence to certain a priori dietary patterns, including the Mediterranean diet, healthful plant-based index, Healthy Eating Index (HEI), and Dietary Approaches to Stop Hypertension (DASH), is associated with a lower risk of CRC. These diets commonly feature high intake of plant-based foods and limited consumption of red and processed meats. Conversely, hybrid dietary patterns such as the Empirical Dietary Index for Hyperinsulinaemia (EDIH) and the Empirical Dietary Inflammatory Pattern (EDIP) show strong probable evidence of increasing CRC risk, likely due to their links to inflammation and insulin resistance. These dietary patterns have high intakes of meat, refined grains and free sugars and ultra-processed foods.

The review finds only limited evidence supporting the role of low-fat dietary interventions in reducing CRC risk, with studies showing no strong or consistent associations. Similarly, a posteriori dietary patterns, including “Western” and “Meat-heavy” diets, did not show conclusive associations with CRC risk, reflecting inconsistencies in their composition across studies. By cancer subsite, the Mediterranean diet appears to be linked to a lower risk of rectal cancer, while HEI and DASH are associated with reduced risks of both colon and rectal cancers.

The study highlights the complexity of assessing dietary patterns, noting that different methods of classification, regional variations, and lifestyle factors can influence findings. While no strong conclusions are drawn regarding dietary patterns and CRC mortality due to limited data, the evidence suggests that diets high in fruits, vegetables, and whole grains, and low in processed meats and inflammatory foods, may play a role in reducing CRC risk. The findings reinforce the need for public health policies promoting balanced dietary patterns as a preventive strategy against colorectal cancer. It’s worth noting that a recent analysis found that in 2018, 21.5% of cancers of the gastrointestinal tract were related to dietary risk factors.

Calcium intake and risk of colorectal cancer

We commonly hear that dairy consumption is associated with a lower risk of CRC. This is true, but it is purely related to the calcium content. This is nicely demonstrated in this new study, which investigates the association between calcium intake and CRC risk using data from the NIH-AARP Diet and Health Study, which followed 471,396 participants aged 50 to 71 years over a median of 18.4 years. The study assessed total calcium intake from dietary and supplemental sources and examined its impact on CRC risk across different tumour sites and racial and ethnic groups. Findings indicate that higher total calcium intake was significantly associated with a lower risk of CRC, with those in the highest quintile of intake experiencing a 29% lower risk compared to those in the lowest quintile. This inverse relationship was consistent across calcium sources, including dairy and non-dairy dietary sources as well as supplements, and was observed for both proximal and distal colon cancers as well as rectal cancer.

Despite overall benefits, the study found no significant association between calcium intake and CRC risk among non-Hispanic Black participants, possibly due to lower overall calcium consumption within this group. The results support prior research indicating calcium's protective role against CRC, potentially through mechanisms such as binding carcinogenic bile acids and fatty acids in the gut or reducing cellular proliferation in the colon. It’s worth noting that the production of carcinogenic or secondary bile acids is higher in people eating a meat-heavy diet. The study emphasises the importance of increasing calcium intake, particularly among populations with lower consumption, as a potential strategy to reduce CRC risk. However, further research is needed to understand variations in risk reduction across different racial and ethnic groups.

Healthy lifestyles after a diagnosis of prostate cancer

All stages of prostate cancer appear to be greatly influenced by lifestyle factors, with a growing body of evidence supporting the role of a plant-based diet. The study investigates the association between lifestyle, diet, and survival outcomes in men diagnosed with non-metastatic prostate cancer (PCa) across diverse racial and ethnic groups. Using data from the Multiethnic Cohort study, 2603 men aged 45 to 75 years were followed for a median of 10.9 years after completing a post-diagnosis lifestyle and dietary questionnaire. The study evaluated three prostate cancer behavior scores and multiple dietary indices, including the Healthy Eating Index-2015 (HEI-2015), Healthful Plant-Based Diet Index (hPDI), and dietary inflammatory and hyperinsulinemia indices.

Results showed that healthier lifestyle behaviors, as measured by the 2021 PCa Behaviour Score (which considers smoking status, BMI, and physical activity), were associated with a significantly lower risk of all-cause and cardiovascular disease (CVD) mortality. Each additional point in the score was linked to a 31% reduction in overall mortality and a 33% reduction in CVD-related deaths. The association was particularly strong among African American men, where higher lifestyle scores were associated with a 54% lower risk of PCa-specific mortality. However, no significant association between lifestyle or dietary scores and PCa-specific mortality was observed in other racial groups.

Regarding dietary patterns, the HEI-2015 and hPDI were associated with reduced all-cause mortality, while the Empirical Dietary Index for Hyperinsulinemia (EDIH) and Energy-Adjusted Dietary Inflammatory Index (E-DII) were associated with increased mortality risk, particularly from CVD. Japanese American men had the highest adherence to healthy diets, while African American and Native Hawaiian men reported higher consumption of pro-inflammatory and pro-insulinemic diets. Although no single dietary pattern showed a significant link to PCa-specific survival, the study underscores the importance of lifestyle and diet in reducing overall and CVD-related mortality among men with prostate cancer. These findings highlight the need for targeted dietary and behavioural interventions to improve survival outcomes in diverse populations. The study reminds us that 85% of deaths in the study population were due to causes other than PCa and thus addressing traditional cardiometabolic risk factors remains equally important in people with cancer.

Diet quality and psoriasis severity

There are limited data on the role of diet in psoriasis in terms of risk and severity. In general, we know that healthier diet patterns are beneficial. This is a welcome new study that examines the relationship between diet quality and psoriasis severity in UK-based adults with psoriasis. Using data from the Asking People with Psoriasis about Lifestyle and Eating (APPLE) study, researchers analysed dietary patterns through a 147-item food frequency questionnaire, assessing adherence to the Mediterranean Diet Score (MDS), Dietary Approaches to Stop Hypertension (DASH) score, and different versions of the Plant-Based Diet Index (PDI). Psoriasis severity was self-reported using the Simplified Psoriasis Index.

Findings indicated that lower adherence to health-promoting dietary patterns was associated with greater psoriasis severity. Individuals with very low adherence to the DASH and healthy Plant-Based Diet Index (hPDI) had significantly higher odds of reporting severe psoriasis. Similarly, those with low adherence to the original Plant-Based Diet Index (oPDI) had an increased likelihood of severe psoriasis. Conversely, individuals with low adherence to the unhealthy Plant-Based Diet Index (uPDI) had a reduced risk of higher psoriasis severity. Further analysis showed that BMI mediated the association between dietary patterns and psoriasis severity, except in the case of the DASH diet, which retained an independent effect.

Specific dietary components were linked to psoriasis severity. Higher intakes of red and processed meat were associated with worse psoriasis outcomes, while greater consumption of nuts, legumes, fruits, and vegetables was correlated with milder symptoms. These results suggest that dietary modifications may be beneficial in managing psoriasis severity and highlight the potential role of nutrition in psoriasis care pathways.

Although the study emphasises the need for further research to explore dietary interventions as an accessible and cost-effective strategy for improving psoriasis outcomes, there are no downsides to supporting people to implement the available evidence and to increase the consumption of plant-based foods. There can be some remarkable health transformations using a diet and lifestyle approach as documented by our patient advocate Kate Dunbar. Her story has been published in a medical journal and she is now 7 years free of medication and symptoms, whilst running marathons following a diagnosis of psoriatic arthritis.

Meat consumption and depression

This systematic review and meta-analysis investigated the association between meat consumption and depression through a meta-analysis of longitudinal studies. Given the inconsistency of prior research, the authors sought to clarify whether low meat consumption—either a meat-free or flexitarian diet—is linked to depression risk while also considering psychosocial factors.

A comprehensive literature search was conducted in multiple databases up to January 2024. The review included only longitudinal studies, ensuring a more reliable temporal relationship between diet and depression. The meta-analysis incorporated 20 samples from 17 studies, including both cohort and case-control designs, covering a total of 64,992 participants.

The results revealed a protective association between meat-free diets (vegetarian and vegan) and depression, with a 26% lower risk of depression among those who avoid eating meat. This association was consistent for cohort studies, studies of higher quality, and the most recently published studies. In contrast, the association between flexitarian diets (low meat consumption) and depression was inconclusive.

The study identified significant sources of heterogeneity, including study design, geographic region, gender inequality, and whether models adjusted for key psychosocial variables such as marital status, employment, and education. Subgroup analysis by population psychosocial variables supported that the relationship between a meat-free diet and depression could be influenced by psychosocial variables.

Despite some limitations, this meta-analysis provides compelling evidence that a meat-free diet may offer mental health benefits. However, it is not clear whether this association is due to dietary factors or psychosocial and cultural factors that motivate people to avoid meat in the diet.

Butter is NOT back

There remains confusion around healthy sources of fat, yet the scientific date has remains consistent for years. This study investigates the relationship between butter and plant-based oil consumption and the risk of total and cause-specific mortality among U.S. adults. Using data from three large, long-term cohort studies—the Nurses’ Health Study, Nurses’ Health Study II, and the Health Professionals Follow-up Study—researchers analysed dietary patterns and mortality outcomes over a period of up to 33 years. Participants included adults without prior cancer, cardiovascular disease, diabetes, or neurodegenerative conditions at baseline, with dietary intake assessed every four years through validated food frequency questionnaires.

The analysis revealed that higher butter consumption was associated with a 15% increase in total mortality risk compared to lower consumption. In contrast, higher intake of plant-based oils, including canola, soybean, and olive oil, was linked to a 16% lower risk of total mortality. Every 10-gram daily increase in plant-based oil intake corresponded to an 11% reduction in cancer mortality risk and a 6% reduction in cardiovascular disease mortality risk. Replacing 10 grams of butter with an equivalent amount of plant-based oils was estimated to reduce total mortality risk by 17% and cancer mortality risk by a similar margin.

The findings suggest that butter, rich in saturated fats, may contribute to higher mortality, while plant-based oils, which contain unsaturated fats, may offer protective health benefits. The study supports dietary recommendations that favour plant-based oils over butter to reduce the risk of premature death. However, limitations include the reliance on self-reported dietary intake and the potential for residual confounding factors.

Butter is definitely not back, and favouring plant sources of fats is definitely a healthier choice.

See you all in April!