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

This month we finally have a new position statement on vegetarian and vegan diets from the Academy of Nutrition and Dietetics. In addition, studies on dementia, time-restricted eating and cancer.

Photo by Victoria Shes on Unsplash

Vegetarian and vegan diets are nutritionally adequate and can offer health benefits:

This month we have the newly published position statement from the Academy of Nutrition and Dietetics. This has been long awaited since the previous statement from 2016 had been withdrawn. Of note, this relates to adults, 18 years and older (non-pregnant/non-lactating). We hope to see additional position statements for children and pregnancy.

The statement reaffirms that vegetarian and vegan diets are nutritionally adequate for adults and can have health benefits, although it correctly emphasises the important of diet quality. It highlights the need for vitamin B12 supplementation and additional potential deficiencies in micronutrients including, iodine, iron, calcium and choline. These can all be easily addressed through food sources and for iodine, either iodised salt, seaweed or supplementation. Fortified plant-based drinks, even if classified as ultra-processed, are acknowledged as a useful source of nutrients such as calcium and it is noted that there are no data to suggest these drinks are harmful. The statement recommends incorporating sources of alpha-linolenic acid (ALA) such as flaxseeds, chia and hemp seeds, but does not find that an algae-derived DHA/EPA is necessary for everyone. In addition, the statement acknowledges there may be benefits of a vegetarian and vegan diet for preventing and managing cardiometabolic conditions such as overweight/obesity, glucose dysregulation/diabetes, high blood lipids and blood pressure. There is also acknowledgment of the association between vegan diets and lower bone mineral density and potential increased risk of fracture. Thus ensuring sufficent intake of calcium and vitamin D and paying attention to diet quality to mitigate against these potential issues is important.

The document is aimed at dietetic, nutrition and health professionals who should have sufficient knowledge to support clients in both the outpatient, inpatient and community settings to adopt a nutrient-dense, vegetarian or vegan diet if that is their wish and that these dietary patterns can be used to manage chronic conditions. We know from our own research survey that dietitians in the UK and Ireland do not feel confident in supporting clients to adopt a plant-based diet, in part because the dietetic curricula do not sufficiently cover the topic and there is a lack of resources for use in clinical practice. It is well worth reading the full position statement which is available open access.

Plant-based diet and risk of all-cause mortality:

Plant-based diets have a number of benefits, especially for cardiometabolic health. The impact on longevity is less well studied. This systematic review and meta-analysis examined the relationship between adherence to a plant-based diet and the risk of cardiovascular, cancer and all-cause mortality. The researchers analysed data from 14 cohort studies, which had used the plant-based dietary index to categorise dietary intake into overall, healthy and unhealthy plant-based diets. The results showed that adherence to a more plant-based diet was associated with a lower risk of death (16% reduction), mostly driven by a reduction in cardiovascular disease (CVD) mortality (13%), with a small reduction in cancer mortality (4%). The benefits were greater in participants adhered to a healthy plant-based diet with reductions in all-cause, CVD and cancer mortality of 15%, 17% and 8%, respectively. In contrast, an unhealthy plant-based diet increased the risk of all-cause (18% increase), CVD (21%) and cancer (11%) mortality.

An additional study to highlight because it includes a non white population is one that used the planetary health diet index to assess adherence to the Eat Lancet Planetary Health Diet (PHD). The analysis used data from the prospective Black Women’s study in the US that followed 33,824 participants for a median of 18 years. It showed that women who adhered most to the PHD had a significantly lower risk of death during the study time period and this was driven mainly by a lower risk of cardiovascular disease. The reason for mentioning this study is that it does not matter what you call a diet, the health benefits are derived from eating whole plant foods. The Eat Lancet PHD is more than 85% plant-based. In addition, this way of eating is also predicted to be able to keep our food system within planetary boundaries, thus limiting the negative impact on environmental health. A win win. However, we need to remember that the quality of diet is key for harnessing the protective properties of a plant-based diet.

By far the greatest health benefit of a plant-based diet is for cardiometabolic health and hence the lower CVD-related mortality. Yet, one topic of continued debate in the nutrition community is the contribution of dietary cholesterol, only found in animal-sourced foods, to heart disease. This new study examines this question by analysing data from the Million Veteran Program, a prospective cohort database collecting genetic and nongenetic factors influencing chronic diseases. Researchers analysed data from 180,156 veterans and assessed the association between dietary cholesterol and myocardial infarction (MI). The results showed a linear, dose–response association between dietary cholesterol intake and risk of MI, with every 100mg/d increment in cholesterol intake associated with a 5% higher MI risk. Participants consuming >300mg/d of cholesterol had a 15% increased MI risk compared with those consuming less than 300mg/d. The authors conclude that public health guidance should recommend limiting the consumption of dietary cholesterol, which means reducing the consumption of meat and egg. The beauty of a plant-based diet is that it is free of dietary cholesterol, whilst also being low in saturated fat.

Plant-based diet and survival among patients with metastatic colorectal cancer

There are limited data on the role of plant-based diets in people with metastatic cancer, so its good to see a study on the topic. The study investigated the impact of a plant-based diet on survival outcomes in people with metastatic colorectal cancer (CRC), a topic that had not been previously explored. Using data from the CALGB/SWOG 80405 clinical trial, researchers analysed dietary habits from 1,284 people who completed food frequency questionnaires at the beginning of their treatment. The study assessed three types of plant-based diets: an overall plant-based diet (PDI), a healthful plant-based diet (hPDI) that emphasised whole grains, fruits, and vegetables, and an unhealthful plant-based diet (uPDI) that included refined grains and sugary beverages.

The findings revealed that patients who adhered most closely to a plant-based diet had significantly better survival outcomes. Those in the highest quintile of PDI experienced a 24% lower risk of death compared to those in the lowest quintile. Similarly, a diet rich in healthy plant-based foods (hPDI) was associated with improved survival, though the statistical significance was slightly weaker. In contrast, consuming a diet high in unhealthful plant foods (uPDI) did not appear to negatively impact survival. When looking at progression-free survival, both PDI and hPDI showed potential benefits, with hPDI demonstrating a modest (20%) but statistically significant improvement.

The study concludes that a plant-based diet, particularly one rich in whole, nutrient-dense foods, may offer survival benefits for patients with metastatic CRC. However, simply reducing animal foods is not enough; the quality of plant-based foods plays a crucial role. These findings highlight the need for further research to better understand the biological mechanisms behind the benefits of a plant-based diet in cancer progression and survival.

On February 4th, World Cancer Day, we launched our new factsheet on lifestyle strategies following a cancer diagnosis. We hope it’s useful given the growing number of cancer survivors. In addition, the World Cancer Research Fund launched their Policy Blueprint for Cancer Prevention. It is a package of policy recommendations for preventing cancer and living well beyond cancer, alongside their Cancer Prevention Recommendations, which have not changed since 2018.

Global food availability falls short in foods that promote health:

We know that our food and farming system does not align with health goals. In the UK, 85% of farmland is dedicated to raising animals for food, leaving only 15% of land used to produce crops for human consumption. This is far removed from the evidence we have showing that the foods that promote good health and prevent chronic conditions are fruit, vegetables, whole grains, beans, nuts and seeds. But it seems this is a global problem. This study examines global food availability in relation to dietary recommendations, highlighting persistent shortfalls and regional disparities in the accessibility of foods essential for health. While the global food supply is sufficient to meet caloric needs, it does not align with healthy dietary guidelines, particularly in terms of fruits, vegetables, and protein-rich plant foods. The research utilised the Healthy Diet Basket (HDB), a global benchmark developed by UN agencies and the World Bank, to evaluate national, regional, and global food supply trends.

The analysis revealed that while some progress has been made, significant gaps remain, particularly in low-income regions where access to nutritious foods is limited. The study identified a persistent undersupply of fruits, vegetables, and legumes, nuts, and seeds, while consumption of starchy staples, animal-source foods, and oils and fats often exceeds recommended levels. These disparities are particularly pronounced in sub-Saharan Africa and South Asia, where food supplies fall well below HDB targets. In contrast, regions like North America and Europe have an oversupply of certain food groups but still lack adequate availability of plant-based protein sources.

The research further explores future projections using economic models, suggesting that increased agricultural investment could slightly improve food adequacy in regions facing chronic hunger. However, even under optimistic investment scenarios, food supply gaps in key nutrient-rich food groups are likely to persist. The findings underscore the need for targeted policies that promote both the production and affordability of under-consumed food groups, particularly in low-income countries.

Overall, the study highlights the limitations of current food systems in providing balanced nutrition and calls for a shift in agricultural investment strategies. Efforts must go beyond increasing overall food production to focus on improving the availability of diverse and nutrient-rich foods. Addressing these shortfalls is crucial for achieving global health and nutrition goals, particularly in the context of climate change and population growth. Forward thinking countries such as Denmark, Portugal and South Korea have already produced policies and action plans to transition to a plant-based food system. We are hoping the new Government in the UK will also follow suit.

Lifestyle intervention for preventing cognitive decline

Dementia remains a key society challenge. We know that up to 45% of case could be prevented if we paid attention to known risk factors. Understanding how to deliver prevention strategies is key. This study investigated the effectiveness of an online multidomain lifestyle intervention aimed at preventing cognitive decline in older adults at risk of dementia. The study explored a scalable and personalised intervention strategy targeting modifiable risk factors.

Conducted as a single-blind randomized controlled trial, the study enrolled 6,104 dementia-free Australian adults aged 55 to 77 years, who had at least two modifiable risk factors for dementia. Participants were randomly assigned to either an intervention group, which received personalised online coaching in physical activity, nutrition (Mediterranean diet), cognitive training, and mental well-being, or a control group that received only general health information without individualised coaching. The primary outcome was cognitive performance, measured using a global cognitive composite score over three years.

The results demonstrated a significant improvement in cognitive function in the intervention group compared to the control group. Specifically, the intervention group showed a greater increase in global cognitive composite scores, with a between-group difference of 0.18 standard deviations (P < 0.001). Secondary outcomes also supported the effectiveness of the intervention, showing improvements in attention, executive function, and memory. Participants who adhered more closely to the intervention demonstrated even greater cognitive benefits. Additionally, health-related outcomes, including physical activity levels, dietary habits, and psychological well-being, improved significantly in the intervention group.

The study found that the intervention was safe, with low rates of adverse events. However, engagement levels varied, with some participants completing all assigned tasks while others engaged minimally. The intervention was particularly beneficial for younger participants (ages 55–65) and women, suggesting that early and targeted interventions may yield the most significant benefits.

Overall, the findings suggest that an online, scalable, and multidomain intervention can effectively improve cognitive function and reduce dementia risk in older adults. This approach has the potential to be implemented at the population level, providing a feasible and accessible strategy for delaying cognitive decline. The study highlights the importance of targeting multiple lifestyle factors simultaneously and reinforces the role of digital interventions in public health strategies for dementia prevention.

Time restricted eating for cardiometabolic health

The topic of fasting still gets a lot of airtime. There are different ways of fasting and it is not clear if the health impact of various fasting protocols relate to their ability to reduce calorie intake or whether there is something more special about fasting per se.

This study explored the effects of one type of fasting protocol where you eat your food with a set time period i.d. time-restricted eating (TRE). The aim was to assess the impact on visceral adipose tissue (VAT) and cardiometabolic health in adults with overweight or obesity. Conducted as a randomised controlled trial, it compared three TRE schedules—an early 8-hour eating window, a late 8-hour eating window, and a self-selected eating window—against a control group receiving usual care, which included education on the Mediterranean diet. The primary goal was to determine whether TRE, regardless of timing, had a significant impact on reducing VAT, a key factor in metabolic health.

A total of 197 participants were randomised into four groups, and their VAT levels were measured using MRI over a 12-week period. The study found no significant differences in VAT reduction among the TRE groups compared to the control group. Additionally, there were no major differences in other key metabolic indicators, including insulin resistance, blood lipid profiles, and blood pressure. However, all TRE groups showed modest weight loss, with participants losing approximately 2.4 to 3.1 kilograms, which was statistically significant when compared to the control group. The early TRE group also demonstrated greater reductions in subcutaneous adipose tissue and improved fasting glucose levels compared to the other groups.

Despite these modest benefits, the study concluded that TRE did not provide additional advantages over adherence to a Mediterranean diet alone in terms of VAT reduction. TRE was well-tolerated, with high adherence rates across all groups, and no serious adverse events were reported. The findings suggest that while TRE may support weight management, its effects on metabolic health markers, particularly VAT, remain uncertain. Future research is needed to explore longer-term effects and whether specific TRE strategies could offer additional metabolic benefits beyond conventional dietary approaches.

This is an evolving field with practitioners and individuals still trying to tease out the place for fasting protocols for prevention and managing chronic conditions. There is also a new large umbrella review that provides a comprehensive overview and in-depth evidence assessment of associations between different types of intermittent fasting and various health outcomes. Overall, the analysis showed that TRE was associated with significant improvements in cardiometabolic parameters, including weight loss, fat mass reduction and improvements in fasting insulin and HbA1c levels. The authors conclude that TRE may have a role to play in improving health outcomes in people living with overweight and obesity.

For me, adding in a period of fasting is secondary to addressing diet quality. You are going to get most of the gains from your diet by centring it around healthy plant-based foods. If you then want to trial fasting to see if that helps you achieve your health goals, then it is worth a try.

See you all in March!