Review of the plant-based lifestyle medicine news April 2024
This month I cover the evolving role of doctors, lifestyle factors and cancer, harms of alcohol consumption, calcium and vitamin D supplementation and the role of our food system in driving climate change.
FROM CHRONIC DISEASE TO CHRONIC HEALTH: This is a much-needed review, which will resonate with many doctors and healthcare professionals who are feeling let down by our ‘sick care’ model. The paper calls for a rethink of priorities whereby the focus of healthcare is to promote health rather than manage chronic diseases. This way, we can make inroads into dealing with the root cause of many of our chronic conditions, which are ultimately linked to lifestyle and environmental exposures. This type of approach will not only benefit the individual but will have benefits for wider society by reducing healthcare expenditure and promoting more sustainable, equitable and environmentally friendly healthcare.
Decades of research demonstrate that the main determinants of our health span are lifestyle and socioeconomic factors. Healthcare needs to incorporate lifestyle interventions into every aspect of the care it delivers, whilst also lobbying for improved socioeconomic conditions for those most in need.
LIFESTYLE CHANGES AND RISK OF CANCER: Rates of cancer are rising disproportionately in young people (less than age 50). A recent report published in BMJ oncology finds that since 1990, the incidence of and death from of early onset cancers have substantially increased globally with the greatest rises seen in breast, tracheal, bronchus and lung, stomach and colorectal cancers. The analysis finds that dietary risk factors (diet high in red meat, low in fruits, high in sodium and low in milk — it’s the calcium! — and whole grains), alcohol consumption and tobacco use are the main risk factors underlying early-onset cancers. An editorial in this week’s Lancet Oncology journal reminds us that almost half of cancers are potentially preventable by addressing lifestyle factors.
The good news is that it is never too late to benefit from lifestyle medicine interventions. The paper highlighted asked whether changing lifestyle habits in midlife impacts cancer risk. The study included 295,865 middle-aged participants from the EPIC study who had completed a lifestyle questionnaire at baseline and during follow-up. At both timepoints, researchers calculated a healthy lifestyle index (HLI) score based on cigarette smoking, alcohol consumption, body mass index (BMI) and physical activity with scores ranging from 0–16. Cancers considered lifestyle-related, i.e. related to smoking and alcohol use, elevated BMI and physical inactivity, are listed in the main paper.
The median time between the two questionnaires was 5.7 years and the median age at follow-up questionnaire was 59 years. During follow up, the greatest change in lifestyle habits was seen in physical activity levels and the least change in smoking rates. There were 14,933 lifestyle-related cancers that occurred after the follow-up questionnaire at a median follow-up of 7.8 years. Each one-point increase in HLI between questionnaires was associated with 4% lower risk of lifestyle-related cancers, with a stronger association in men than women. Improvements from the lowest third of the HLI score (0–9 points) to the highest (12–16 points) were associated with a 25% risk reduction of lifestyle-related cancers, while declines from the highest to the lowest third were associated with a 21% increased risk of lifestyle-related cancers. Researchers estimated that 5.6% of the observed lifestyle-related cancers were attributable to unhealthy lifestyle changes.
The authors emphasise that the association between lifestyle changes and risk of lifestyle-related cancer was bidirectional, meaning that changing from an unfavourable to a favourable lifestyle was associated with a reduced risk of lifestyle-related cancer, while changing from a favourable to an unfavourable lifestyle was associated with increased risk of lifestyle-related cancer. In addition, the results showed that the maintenance of a healthy lifestyle was associated with the lowest risk of lifestyle-related cancers. The authors also estimated that if all participants had improved their lifestyle by any extent there would have been 7.4% fewer lifestyle-related cancers. At a population level, this has the potential to have a huge impact. It’s a shame that dietary data were not sufficiently robust to use in the HLI score and we await further studies that include dietary risk factors.
The term lifestyle-related cancers can be emotive as it suggests an element of choice and therefore blame. However, we know that socioeconomic factors often determine our ability to embrace healthy lifestyle habits, and thus we need a shift in healthcare and society as a whole to ensure healthy lifestyles are accessible to all.
EARLY-ONSET COLORECTAL CANCER: The recent rise in rates of colorectal cancer in people under the age of 50 years has led researchers to hypothesise the role of modifiable lifestyle factors. This study investigates the role of both genetic and modifiable risk factors in determining the risk of early onset colorectal cancer. By using Mendelian randomisation, it is possible to infer causation between an exposure and outcome without the risk of confounding and reverse causality.
The results of this study find two new genetic loci that are associated with colorectal cancer risk, with a potential new mechanisms of cancer development relating to insulin signalling, immune and infection-related pathways. With regards modifiable risk factors, the results showed potential causal relationships for higher levels of body size and metabolic factors — such as body fat percentage, waist circumference, waist to hip ratio, basal metabolic rate, and fasting insulin — higher alcohol drinking, and lower education attainment. This is concordant with prior data that have highlighted the importance of metabolic health on cancer risk. Regarding educational attainment, it suggests an association with socioeconomic determinants of health and related behavioural risk factors. The largest effect size of risk factors was observed with alcohol, educational attainment and fasting insulin. Interestingly, smoking, coffee consumption, leisure screen time and blood concentrations of vitamin D, calcium, and iron were not associated with cancer risk.
These results suggest that public health interventions addressing both alcohol consumption and metabolic risk factors are needed to reduce the risk of early-onset colorectal cancer along with a focus on socioeconomic determinants of health.
ALCOHOL CONSUMPTION AND RISK OF DEATH: This study is useful in that it uses Mendelian randomisation to address the important question of the impact of alcohol consumption on health outcomes. Many still believe that low level alcohol consumption compared to abstinence is better for health. However, the typical J shaped curve often seen when studying the impact of alcohol of health suffers from the impacts of confounding and reverse causation. That is, people with a chronic health condition may then decide to stop drinking and thus abstaining from alcohol consumption appears to be associated with worse health outcomes. The use of Mendelian randomisation to assess the impact of genetically predicted alcohol consumption can assess the true impact of alcohol consumption without this risk of confounding.
This study used data from participants in the UK Biobank study. It included 278 093 white-British participants, aged 37–73 years at recruitment, with available data on alcohol intake, genetic variants, and mortality. Participants were followed for a median of 12.5 years, during which time 20,834 deaths had occurred. In the conventional analysis there did appear to be a J shaped curve with both high and no alcohol consumption increasing the risk of premature death. However, with Mendelian randomisation, there was a linear relationship between alcohol consumption and risk of premature death. For each standard unit increase in alcohol intake there was a 27%, 30%, 20% and 106% increased risk of all-cause mortality, cardiovascular disease, cancer and digestive disease mortality, respectively. There was no clear evidence for an association between alcohol consumption and mortality from respiratory diseases or COVID-19. The authors conclude ‘Higher levels of genetically predicted alcohol consumption had a strong linear association with an increased risk of premature mortality with no evidence for any protective benefit at modest intake levels. While the greatest mortality risks are associated with heavy drinking, public health initiatives should prioritize efforts to reduce alcohol intakes at all levels of consumption. A re-evaluation of current public policies regarding drinking guidelines may be warranted.’
Sadly, alcohol policy is hugely influenced by the industry who want to keep us buying and consuming alcohol. Let’s hope Governments and policy makers are willing to put into action the scientific evidence when developing their guidance on alcohol consumption. This should clearly state that zero is the optimal amount.
ADHERENCE TO LIFESTYLE GUIDELINES IN CANCER SURVIVORS: The American Cancer Society has comprehensive guidance on lifestyle recommendations for cancer prevention and for living well after a cancer diagnosis. This short report assesses adherence to these guidelines in a cohort of 10,020 people who have had a diagnosis of cancer and completed treatment. The researchers assessed adherence to guidelines for physical activity, body mass index, alcohol use, and fruit and vegetable intake.
The results showed that 72% of cancer survivors met criteria for adequate physical activity, 68% did not have obesity, 12% ate adequate fruits and vegetables, and 50% (95% CI, 49%-52%) did not drink alcohol. In total, 4% of cancer survivors adhered to all 4 guidelines, with the mean number of recommendations being met being 2.0.
I am actually quite surprised that so many people met physical activity guidelines but not surprised at how poorly people are adhering to healthy eating recommendations. In the UK, <1% of citizens adhere to the Eatwell Guide recommendations. There is obviously a lot of scope to support people living with and beyond cancer to improve their diet quality which has the potential to improve overall health, cancer outcomes and quality of life.
CALCIUM AND VITAMIN D SUPPLEMENTATION IN OLDER WOMEN: This paper reports the long-term outcomes in one of trials undertaken as part of the Women’s Health Initiative. The study included 36, 282 postmenopausal women. They were randomised to 1000 mg of calcium carbonate (400 mg of elemental calcium) with 400 IU of vitamin D3 daily or placebo for 7 years. The outcomes reported in this paper were incidence of colorectal, invasive breast, and total cancer; disease-specific and all-cause mortality; total cardiovascular disease (CVD); and hip fracture.
With this 20 years follow, the data show that supplementation with calcium and vitamin D increased the risk of CVD mortality by 6% but reduced the risk of cancer mortality (breast, colorectal and all cancer) by 7%. So overall, the impact of supplementation was neutral. The was no impact, neither positive or negative, on the other health outcomes analysed including fracture risk, CVD, or cancer incidence or all-cause mortality. The positive impact on cancer mortality was greater in those without prior supplementation use, suggesting there is a biological basis to the findings.
Things to know about the study and its participants. 50–60% of participants were using supplements prior to entry into the study. The mean vitamin D level of participants was in the normal range, thus suggesting that the positive impacts of vitamin D supplementation relate to higher vitamin D levels than what would normally be aimed for to prevent fractures. The study cannot disentangle the impacts of vitamin D and calcium individually as both were taken together. The negative impact on CVD mortality was not shown at earlier follow up but only apparent after this long follow-up period. If truly casual, this is thought to be due to increased calcification of coronary arteries as shown by some by not all prior datasets.
My personal view here is that calcium is best obtained from dietary sources. Higher than nutritional doses of calcium do not benefit bone health and may increase the risk of CVD. Aim for a vitamin D level in the normal range. For people with a diagnosis of cancer, aim for a higher vitamin D blood level (>75nmol/l).
PLANT-BASED DIETS AND PLANETARY HEALTH: Healthcare systems around the world are focussing on sustainability given that healthcare is responsible for around 6% of greenhouse gas emissions. Yet diet change and food system transition are almost never sufficiently emphasised. My own haematology conference this week served lamb on day one! Diet change is undoubtably the single most impactful action we can take as individuals and communities to reduce our impact on the planet. Sustainable healthcare to me is prioritising prevention over treatment and reducing our reliance on pharmaceutical interventions. Thus, supporting patients and staff to adopt a plant-based diet could have a huge impact. I was therefore delighted to have the opportunity to write about plant-based diets for the Royal College of Pathologist’s in their series on climate health.
Sustainability is key to future proofing the NHS as highlighted in this excellent article in the BMJ. The article does not sufficiently emphasise the importance of diet change and food system transition, given the co-benefits for individual, population and planetary health. You can read my response to the article here. (scroll down a little).
PLANT-BASED BY DEFAULT: We now have excellent data in the hospital setting that a plant-based by default approach, pioneered by the organisation Greener by Default, can increase the number of people choosing plant-based meals, without restricting choice, and can result in benefits for health, environment and economy. Read the two year data from New York Health and Hospitals here. This new paper reports positive outcomes of such an approach on college campuses in the US.
The study was conducted over 3 months in 3 private research university cafeterias. These cafeterias allowed diners to choose from many food stations and take as many dishes as they wanted. One station in each cafeteria received the experimental manipulation. Under the plant-based default condition, the signage listed both options, however it listed the vegan dish first, followed by the meat dish which was available “upon request”. Only the vegan dish was displayed at the counter, with the meat dish kept in a separate location and retrieved when it was requested.
The results showed that a vegan default intervention was able to reduce meat consumption by 57% and increasing vegan meals selected by 58% at the cafeteria stations with the intervention. This demonstrates the power of behavioural interventions that do not limit choice. The teams involved are now starting a more widespread role out of this strategy in college campuses.
Given what we know about the impact of animal farming and meat and dairy consumption in the UK, it is high time these strategies were implemented. In the UK, 74% of agricultural emissions come from the production of red meat and dairy, whilst their excess consumption is leading to 42,000 deaths per year. We have some amazing work already undertaken and ongoing by ProVeg and its School Plates programme and Plant Based Universities. Let’s hope healthcare institutions are next.
LISTERIOSIS AND VEGAN CHEESE: A word of caution around the consumption of vegan cheeses, particularly during pregnancy. This article, which I was surprised to find in such a high-profile journal, reports the outbreak of listeria in 7 people linked to vegan cheeses and their production environment. Six of the 7 cases occurred during pregnancy leading to complications and one in a three-year-old. These raw vegan cheeses can become contaminated from environmental exposure in the production environment during fermentation and if not pasteurised can pose a risk, especially in pregnancy. One should also take care when eating unpasteurised foods such as kimchi, sauerkraut and sprouts if pregnant or immunosuppressed.
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