The top science papers of 2024 supporting lifestyle medicine
From chronic disease to chronic health, lifestyle medicine is heralded as the solution to our epidemic of chronic ill health.
Prevention is at the heart of the recommendations of this year’s independent investigation of the NHS in England conducted by Lord Darzi. He found the NHS to be ‘in critical condition, but it’s vital signs are strong’. However, the burden of preventable chronic conditions is crippling primary, secondary and social services. The number of people living with a chronic long-term conditions in the UK continues to rise with projections of 18.2 million by 2040. This is where lifestyle medicine could provide a viable solution. Here are my favourite studies of 2024.
Lifestyle factors trump genetics: A common question is how modifiable lifestyle factors impact genetic predisposition to certain conditions. This paper is the first to investigate the joint association of genetic risk and lifestyle factors with human lifespan.
The study analysed data from participants in the UK Biobank study. 353,742 adults were divided into three groups based on a polygenetic risk score for lifespan: favourable (23.1%), intermediate (55.6%), and unfavourable (21.3%). Lifestyle factors were used to create a healthy lifestyle score. This included: no current smoking, moderate alcohol consumption, regular physical activity, healthy body shape, adequate sleep duration, and a healthy diet. Participants were categorised into favourable, intermediate, and unfavourable lifestyles. Of note, a healthy diet was defined as: Fruits: ≥ 3 servings/day, Vegetables: ≥ 3 servings/day, Fish: ≥2 times/week, Processed meats: ≤ 1 times/week, Unprocessed red meats: ≤ 2 times/week, Whole grains: ≥ 3 servings/day, Refined grains: ≤2 servings/day.
Over a median follow-up of 12.86 years, there were 24,239 deaths. The results showed that genetic risk and lifestyle scores were independently associated with lifespan. A high genetic risk resulted in a 21% increased risk of death compared with a low genetic risk and this was independent of lifestyle factors. An unfavourable lifestyle was associated with an approximately 78% increased risk of death compared with a favourable lifestyle within and across genetic risk categories. When assessing both genetic risk and lifestyle scores, those with a genetic propensity for a short lifespan and an unfavourable lifestyle had 104% higher rates of death. In contrast, individuals with a genetic propensity for a short lifespan but a favourable lifestyle had 54% lower rates of death than those with a genetic propensity for a short lifespan and an unfavourable lifestyle. The life expectancy at 40 years was 52.5 years for participants with a genetic propensity for long lifespan and a favourable lifestyle and was 45.8 years for participants with a genetic propensity for short lifespan and an unfavourable lifestyle with a mean difference of 6.7 years in lifespan. Among individuals with a genetic propensity for short lifespan, those with a favourable lifestyle would have 5.2 years longer lifespan than those with an unfavourable lifestyle.
So what do all these figures mean? The authors state ‘Adherence to healthy lifestyles could largely attenuate the genetic risk of shorter lifespan or premature death’. Overall, the genetic risk of a shorter lifespan or premature death might be offset by a favourable lifestyle by approximately 62%, adding around 5 years to life.
These results speak to the common refrain ‘Genetics load the gun, but lifestyle pulls the trigger’.
Lifestyle medicine can increase lifespan: This study included 276,132 veterans (mostly male) in the Million veteran program, aged 40–99 years at recruitment between 2011–2019. Data on 8 healthy lifestyle factors were available at baseline. 1) Whole-food, plant-predominant eating pattern assessed using the healthful plant-based diet index, never smoking, no excessive alcohol consumption, avoiding other risky substances particularly opioids, restorative sleep (7–9hrs per day), managing stress (using a health questionnaire), meeting physical activity guidelines and social connections.
During the follow up period, 34,247 deaths were recorded. The analysis showed that each healthy habit was associated with a significant reduction in premature mortality, ranging from 5–56% risk reduction. Lifestyle factors were responsible for 64% of the risk of dying, with the greatest negative impact coming from physical inactivity, ever smoking, and an eating pattern not consistent with whole-foods or primarily plant-based.
At the age of 40, participants with 8 healthy lifestyle factors had a life expectancy of 47 years. In contrast, those with no healthy habits only lived another 25 years. This benefit held true even after adjusting for social determinants of health. Thus, healthy habits added more than 20 years extra to life expectancy! Prior studies have shown these extra years are usually lived in good or better health.
An observational study of nearly 20,000 participants from Taiwan showed that people who adhered most closely to 5 healthy habits (not smoking, avoiding excessive alcohol consumption, engaging in sufficient physical activity, ensuring sufficient fruit and vegetable intake, and maintaining a normal weight) had a longer life expectancy of around 7 years and a 28% lower expenditure on healthcare.
Lifestyle medicine for prevention of cognitive decline and dementia: Alzheimer’s disease and other dementias are now the leading cause of death in the UK. Currently more than 55 million people are living with dementia worldwide, and there are nearly 10 million new cases diagnosed every year. In 2019, the estimated total global societal cost of dementia was US$ 1.3 trillion, and these costs are expected to surpass US$ 2.8 trillion by 2030 as both the number of people living with dementia and care costs increase. Nearly 85% of costs are related to family and social rather than medical care.
Since 2017 the Lancet Commission on Dementia has highlighted the potential for prevention. The original report suggested that 35% of cases could be prevented through modifiable lifestyle risk factors. These risk factors include tobacco smoking, physical inactivity, depression, hypertension, obesity, diabetes, hearing loss and social isolation. The second report from 2020 added three additional risk factors; excessive alcohol consumption, air pollution and traumatic brain injury. The updated report from 2024 adds two further risk factors; visual loss and high LDL-cholesterol. With these 14 risk factors, it is now predicted that up to 45% of cases of dementia could be prevented or delayed. The 2024 report specifically recognises the importance of healthy diets with a focus on the Mediterranean and MIND (Mediterranean-DASH Diet Intervention for Neurodegenerative Delay) diet. It should be noted that the studies informing these recommendations are mostly performed in high income countries, whereas the burden of dementia is greater in low- and middle-income countries and therefore the potential for prevention may be even greater.
The underlying pathogenic mechanisms in dementia include inflammation, oxidative damage, vascular endothelial damage, dyslipidaemia, glucose dysregulation and insulin resistance. The neuropathology of the disease includes the accumulation of amyloid beta plaques, neurofibrillary tangles, neurone and synapse loss. The onset of AD is preceded by a long preclinical phase, as long as 15 to 20 years, which includes changes in biomarkers and metabolic and behavioural parameters. This long pathological process offers opportunities for prevention. Another interesting observation made by the Lancet Commission is that cognitive reserve i.e. preservation of cognition or everyday functioning, can be increased or maintained despite the presence of brain pathology and neuropathological changes associated with dementia. Early-life factors, such as less education, affect the resulting cognitive reserve. Midlife and old-age risk factors influence age-related cognitive decline and triggering of neuropathological developments.
It is clear that lifestyle approaches throughout the life course have a key role in supporting brain health and preventing dementia. Recent studies show that the beneficial impact of healthy habits are independently associated with a lower risk of cognitive impairment and dementia, regardless of genetic risk or the presence of brain pathology determined at autopsy.
Can intensive lifestyle interventions treat mild cognitive impairment or early Alzheimer’s disease? This is the study we had all been waiting for. It is the latest research from Dr Dean Ornish and colleagues using his intensive lifestyle medicine intervention in people with early stages of Alzheimer’s disease (AD).
This was a multi-centre, randomised, controlled phase 2 trial with a 1:1 randomisation. It included participants with mild cognitive impairment (MCI) or early dementia due to AD. The experimental group underwent a 20-week intensive multi-domain lifestyle intervention, while the control group received usual care and were placed on a wait-list. Primary Outcomes: Changes in cognitive and functional tests including Clinical Global Impression of Change (CGIC), Alzheimer’s Disease Assessment Scale-Cognitive Subscale (ADAS-Cog), Clinical Dementia Rating–Sum of Boxes (CDR-SB), and Clinical Dementia Rating Global (CDR-G). Secondary Outcomes: Plasma Aβ42/40 ratio, other biomarkers, and the correlation between lifestyle changes and the degree of change in these measures.
The lifestyle interventions included a 100% whole food plant-based diet with food delivered to the participants and their spouse/study partner; exercise with 30 minutes of walking a day and mild strength training exercises at least three times per week; stress management with meditation, gentle yoga-based poses, stretching, progressive relaxation, breathing exercises, and imagery for a total of one hour per day; Group support with participants and their spouses/study partners participating in a support group one hour/session, three days/week. To reinforce this lifestyle intervention, each patient and their spouse or study partner met three times/week, four hours/session via Zoom: one hour of supervised exercise (aerobic + strength training), one hour of stress management practices (stretching, breathing, meditation, imagery), one hour of a support group, one hour lecture on lifestyle.
A large number of supplements were used in the intervention group including, omega-3 fatty acids and curcumin, multivitamin and minerals, co-enzyme Q10, vitamin C, vitamin B12, magnesium, Hericium erinaceus, Super Bifido Plus Probiotic.
51 patients enrolled with a mean age of 73.5 years. Baseline characteristics were similar between the two groups. Two participants in the intervention group withdrew from the study. The following results were reported.
- Primary Outcomes:
- CGIC: Significant improvement in the intervention group (p = 0.001).
- CDR-SB: Less progression in the intervention group (p = 0.032).
- CDR Global: Significant improvement in the intervention group (p = 0.037).
- ADAS-Cog: Borderline significant improvement in the intervention group (p = 0.053).
- Secondary Outcomes:
- Plasma Aβ42/40 ratio: Increased in the intervention group and decreased in the control group (p = 0.003).
- Lifestyle Correlation: Significant correlation between lifestyle changes and both cognitive function improvement and plasma Aβ42/40 ratio changes.
- Microbiome: Improved significantly only in the intervention group (p < 0.0001).
Although not everyone in the intervention group showed improvements, when compared with the control group, none of the participants showed improvement in the various parameters, but similar numbers remained stable compared to the intervention group and more showed worsening of the disease. Like with all Dr Dean Ornish’s studies, the more adherent participants were to the lifestyle interventions, the greater the observed benefits
The authors conclude that comprehensive lifestyle changes, including diet, exercise, stress management, and social support, can significantly improve cognition and function in patients with MCI or early dementia due to AD after 20 weeks. This suggests that intensive lifestyle interventions can be beneficial for individuals already diagnosed with early stages of AD.
This study is a huge contribution to the field of lifestyle medicine and provides hope to many with early stages of dementia with an intervention that has no side-effects and can also benefit overall physical and mental health and wellbeing. However, I was a little disappointed that the study was small (albeit able to detect statistically significant differences between groups) and quite short term (20 weeks) and hope that participants will be followed for longer. In addition, I was surprised by the extensive use of supplementation. It is also disappointing that there is no way of teasing out which aspect of the lifestyle intervention is responsible for the greatest clinical impact. May be that does not matter, since all aspects are known to benefit health. We certainly cannot extrapolate these data to say that a 100% whole food plant-based diet benefits people with early dementia, since we cannot be certain of its impact in isolation.
Intensive lifestyle interventions for rheumatic conditions: This year saw two exciting new publications from friends and colleagues in the Netherlands. Last year, I reported on two publications from the Plants for Joints study in my top papers of 2023. The research team conducted two separate randomised studies using a lifestyle intervention of 16 weeks duration in people with rheumatoid arthritis (RA) and osteoarthritis (OA). The intervention was modelled on Dr Dean Ornish’s lifestyle programme and included a whole food plant-based diet, physical activity, sleep and stress management. In both studies, participants improved cardiometabolic risk factors and demonstrated improvements in disease activity and symptoms.
In 2024, the Plants for Joints research team reported the results of the 1-year observational extension study for both cohorts. After the 16 weeks randomised portion of the study, those in the control group could start the Plants for Joints programme. 65 participants in the RA study and 49 in the OA study were included in the 1-year extension analysis.
Overall, the results showed that significant improvements in disease activity and symptoms (pain, stiffness and physical function) were sustained. In the OA group, there was some regression back to starting symptoms, but the improvements still remained significant. Improvements in CRP, waist circumference (RA and OA), low-density lipoprotein cholesterol (RA), and weight, haemoglobin A1c, blood pressure (OA) were also sustained. There was a decrease in medication use, such that 50% of people with RA were able to reduce or stop their anti-rheumatic medication (mean dose reduction of 62%) and of those using pain medication in the OA group, 67% were able to reduce or stop their pain medication. Overall adherence remained high, indicating the intervention is feasible and acceptable in the long run. A trend towards greater improvement of symptoms with better adherence was found but even those who were less adherent to the lifestyle programme showed significant improvements in disease activity and symptoms.
The team also published a secondary analysis of the study demonstrating significant weight loss, body fat loss and lowering of liver fat in people in the lifestyle intervention group, whilst preserving muscle mass and body mineral density.
All in all, these data provide people with arthritis with an alternative approach to medications alone and provide hope that symptoms may improve to an extent to which medications can be reduced or even eliminated, whilst also improving cardiometabolic health. Listen to one of the co-investigators, Dr Carlijn Wagenar talk about the study findings on this episode of In a Nutshell podcast.
Lifestyle medicine and 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 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 the 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. This paper 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.
Similarly, healthy habits after a diagnosis of cancer is associated with a significant reduction in all-cause mortality, cancer-specific mortality and CVD incidence.
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.
Lifestyle medicine for type 2 diabetes: Lifestyle medicine interventions are hugely important in preventing and managing type 2 diabetes. This study specifically investigated the impact of a lifestyle intervention on the development of type 2 diabetes in people with different genetic risk for the condition. It included 973 men from the Metabolic Syndrome in Men (METSIM) cohort, aged 50-75 years, body mass index ≥25 kg/m2, fasting plasma glucose 5.6-6.9 mmol/L, haemoglobin A1c < 48 mmol/mol. They were divided into low and high genetic risk groups based on a genetic risk score calculated from the analysis of 76 known genetic variants related to diabetes. Population controls (n = 589) were selected from the METSIM cohort and had similar inclusion criteria as the participants in the intervention group, but they were invited only for 3-year measurements.
The 3-year intervention included group sessions on the importance of a healthy diet and physical activity. Dietary guidance followed Nordic and Finnish nutrition recommendations, emphasising appropriate energy intake; meal frequency; consumption of fruits, vegetables, and berries; and quality of dietary fat and carbohydrates, including fibre and sugar intake. Regarding weight management, the minimum goal for the participants was weight maintenance. The goal for physical activity was brisk walking or other types of physical activity ≥30 minutes/day at least 5 times a week.
After 3 years, in the intervention arm, the conversion to diabetes was 7.7% in the low and 7.9% in high genetic risk groups. In the population control arm, 8.2% of the participants in the low genetic risk group and 14.1% of the participants in the high genetic risk group developed type 2 diabetes. Overall, the intervention lowered the risk of type 2 diabetes by 52%. Among the participants with a high genetic risk for type 2 diabetes, the intervention lowered the risk of type 2 diabetes by 70% whereas among the participants with a low genetic risk for type 2 diabetes, there was no significant difference in incident type 2 diabetes between the intervention and control arms. However, the intervention effect was not significantly different between the high and low genetic risk groups, suggesting that the participants having a low genetic risk for type 2 diabetes also benefitted from lifestyle intervention. The participants in the intervention arm lost more weight and had a larger decrease in BMI compared with the population controls, irrespective of genetic risk. Dietary intake of saturated fatty acids decreased and intakes of monounsaturated fatty acids, polyunsaturated fatty acids, fibre, and fruits, vegetables, and berries increased significantly in the intervention arm and similarly in both genetic groups.
Overall, this study confirms that low-cost lifestyle interventions are effective at preventing the development of type 2 diabetes. The novel aspect was that the intervention was also effective in people at high genetic risk. The authors conclude ‘Our results suggest that all individuals at risk of type 2 diabetes should be encouraged to make lifestyle changes regardless of genetic risk.’
Maintaining a healthy weight is key for preventing type 2 diabetes. Once a diagnosis of pre-diabetes or diabetes is made, weight loss is the main goal. The UK has pioneered low calorie diets using meal replacement shakes and soups for inducing diabetes remission. Prof Roy Taylor and colleagues ran the seminal study called the DIRECT trial, which showed that their total diet replacement formula resulted in significant weight loss and could achieve diabetes remission. The 5 year follow up of this study has now been published. This approach has been adopted within the NHS and real-world data has also been published using three months of total diet replacement and 12 months of behavioural intervention to support weight loss. The programme resulted in a 27% remission rate. But don’t forget that a whole food plant-based diet is a very effective dietary intervention for diabetes remission as evidence by this new study from 2024 by Brenda Davis RD, Dr John Kelly and colleagues.
Healthy lifestyles and COVID-19: I wrote a lot about diet and lifestyle approaches during the COVID-19 pandemic as it was clear early on that people with healthier lifestyles and less chronic conditions had a better outcome from the infection. You can find my articles here. Scroll down for all the scientific evidence as it emerged over the two year period. Now, over four years from the start of the pandemic, the scientific evidence once again highlights the importance of lifestyle factors for predicting the severity of COVID-19.
This study assessed the impact of lifestyle factors on infection severity in 68,896 participants of the UK biobank study who had a positive SARS-CoV-2 test result between March 1, 2020 and March 1, 2022. Ten pre-specified potentially modifiable lifestyle factors were assessed, including smoking, alcohol consumption, BMI, physical activity, sedentary time, sleep duration, intake of fruit and vegetable, intake of oily fish, intake of red meat, and intake of processed meat. A healthy diet was deemed that which was consistent with UK healthcare and Government guidance (i.e. similar to the Eatwell guide).
The results showed that a favourable lifestyle score was associated with a lower risk of hospitalisation (22% reduction) and death (41% reduction). In addition, adherence to healthy lifestyle habits resulted in a lower risk of multi-organ sequelae of infection, aka long-COVID (36% reduction). These beneficial impacts occurred during both the acute and post-acute phases of SARS-CoV-2 infection and were independent of underlying pre-existing health conditions. The reduced risk of multisystem sequelae associated with a healthy lifestyle was consistently observed across participants, regardless of their vaccination status, disease severity (testing positive in community/outpatient settings or inpatient settings), and major SARSCoV-2 variants, including Omicron variants. The benefits were found to be larger than those observed in previous studies of pharmaceutical interventions in non-hospitalised patients. The authors conclude ‘These findings suggest the benefit of population adhering to a healthy lifestyle to reduce the potential long-term adverse health consequences of COVID-19.’
When it comes to diet, a number of studies have now shown that people who adhered most to a healthy plant-based diet had reduced severity and impacts from the infection, in part due to the favourable effects of a plant-based diet on the gut microbiome and hence inflammation and immune health.
Alcohol consumption and risk of death: Alcohol consumption is still socially acceptable despite the evidence showing that is causes health harms. 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.
Conclusions: Another year and more evidence that lifestyle medicine could provide a meaningful way of moving from a sickness model of healthcare to one that creates good health. This requires healthcare professionals to reconsider their role and the way they practice as described in this article ‘From chronic disease to chronic health: the evolving role of doctors in the 21st century’ in order to improve quality and quantity of life. There are several country-based examples from which to learn from, where interventions have led to improvements in healthy life expectancy, for example in Japan, Korea, Ireland and Singapore. In addition, New York City has pioneered a city-wide lifestyle medicine programme encompassing primary and secondary care and healthcare staff. Let’s hope the new UK Government prioritises health promotion and lifestyle medicine.
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