A review of the plant-based nutrition news February 2023

After more than 3 years of writing a weekly review I am moving to a monthly offering. This month I focus on the power of healthy lifestyle habits. I am excited to be leading two sessions on plant-based lifestyle medicine at the British Society of Haematology annual conference in April 2023.

Last month the Times Health Commission report recognised the huge contribution that unhealthy diets and lifestyles are making to the national health crisis. The symptoms of this crisis are the rising rates of obesity and type 2 diabetes in both children and adults, but the report clearly states that ‘diet, a lack of physical activity, smoking and alcohol account for around 80 per cent of non-communicable diseases’.

This is not new information. The INTERSTROKE study, an international case-control study of about 27,000 participants, found that about 90% of stroke risk is associated with ten potentially modifiable risk factors — hypertension, smoking, diabetes, physical activity, diet (determined by the Alternative Healthy Eating Index), psychosocial factors, abdominal obesity, alcohol, cardiac causes (including atrial fibrillation, myocardial infarction), and dyslipidaemia. The INTERHEART study, an international case-control study of almost 30,000 participants found that more than 90% of heart attack risk is associated with nine potentially modifiable risk factors — abnormal lipids, smoking, hypertension, diabetes, abdominal obesity, psychosocial factors, consumption of fruits, vegetables, and alcohol, and regular physical activity.

The 2020 Lancet commission on dementia reported that 12 modifiable risk factors could prevent or delay 40% of cases of dementia and for cancer, almost 50% of cases could be prevented by addressing both behavioural and metabolic risk factors.

This is why the evidence-based speciality of lifestyle medicine is the fastest growing medical speciality globally. The practice of lifestyle medicine addresses six pillars of healthy living: diet, physical activity, sleep, stress management, healthy relationships and avoidance of harmful substances, including tobacco and alcohol. I believe that lifestyle medicine could hugely benefit patients with haematological disorders too (more about that next month).

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HEALTHY LIFESTYLES AND LONG COVID: A post viral syndrome termed long COVID or post COVID-19 syndrome seems to affect around 1 in 20 people following infection with SARS-CoV-2. It is more common in those who had more severe acute disease but may occur after mild or even asymptomatic disease. It is more common in people who were hospitalised, aged 35 to 69, female, living in deprived areas, working in healthcare, social care, or education, with high body mass index (BMI), and with more than one pre-existing, activity limiting health condition. Like other post viral syndromes it is thought to be related to ongoing low-grade inflammation and an abnormal immunological response to the virus. The current mainstay of treatment is a supportive, holistic approach. It is therefore crucial to understand modifiable factors that will help reduce the incidence and prevalence of this conditions.

The study highlighted examines the impact of healthy lifestyle factors on the risk of long COVID. The researchers analysed data from more than 32,000 female nurses in the Nurses’ Health Study II, who reported on lifestyle in 2015 and 2017 and a history of SARS-CoV-2 infection from April 2020 to November 2021. During that time, more than 1,900 participants contracted COVID-19. Healthy lifestyle factors examined included healthy BMI, at least 150 minutes per week of moderate to vigorous physical activity, moderate alcohol intake (5 to 15 g/d), high diet quality (upper 40% of Alternate Healthy Eating Index–2010 score), and adequate sleep (7 to 9 h/d).

Among these participants, 44% developed long COVID. Compared to women without any healthy lifestyle factors, those with five or six had a 49% lower risk of long COVID. Each of the six healthy lifestyle factors reduced the risk of long COVID in a dose-dependent manner although maintaining a healthy body weight and getting adequate sleep had the greatest impact. The results also showed that even among women who developed long COVID, those with a healthier pre-infection lifestyle had 30% lower risk of having symptoms that interfered with their daily life. These associations were independent of socioeconomic factors and pre-existing medical conditions. If these associations were causal the researcher hypothesis that 36% of long COVID cases would have been prevented if everyone adhered to 5 or 6 healthy lifestyle factors.

The researchers suggest that the benefits of these healthy lifestyle habits are likely to relate to lower levels of inflammation and a healthier immune response as a result of healthier lifestyle habits. Prior studies have also indicated that the health of the gut microbiome is important and all these healthy lifestyle habits (except perhaps for alcohol!) promote better gut health.

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HEALTHY LIFESTYLE AND MEMORY LOSS: Given the lack of medical treatment for cognitive decline and dementia, lifestyle interventions remain key. This study investigated the association between a healthy lifestyle and memory decline over 10 years among 29, 000 participants (49% were women, mean age was 72.2 years at baseline) in the China Cognition and Ageing Study. The authors calculated a healthy lifestyle score combining six factors: healthy diet, regular physical exercise, active social contact, active cognitive activity, not smoking, and never drinking alcohol. For diet, researchers recorded the participant’s daily intake of 12 food items (fruits, vegetables, fish, meat, dairy products, salt, oil, eggs, cereals, legumes, nuts, and tea). A healthy diet was high in healthy plant foods but still included meat, dairy and eggs at low levels of consumption and fish consumption was counted as healthy. The resulting score, ranging from zero to six healthy factors, was categorised as favourable (four to six factors), average (two to three), or unfavourable (zero to one).

The results showed that each individual healthy behaviour was associated with a slower decline in memory over 10 years. A healthy diet had the strongest effect on memory, followed by active cognitive activity. This positive impact was dose dependent. The higher the lifestyle score the slower memory decline.

A noteworthy finding was that the association between healthy lifestyle score and 10-year memory decline was evident in people who did and did not carry the APOE ε4 allele. APOE ε4 is the strongest known risk factor for Alzheimer’s disease and related dementias. These results support the notion that lifestyle change might counteract the negative impact of APOE ε4 on cognitive decline and dementia.

Importantly, over 10 years of follow-up, a favourable lifestyle was associated with a lower probability of progression to mild cognitive impairment and dementia. Those adherent to the healthy lifestyle behaviours had an almost 90% reduction in the risk of progression to dementia and this favourable impact was also apparent in those participants carrying the APOE ε4 allele. This positive impact of healthy lifestyle habits on people with high genetic risk has been previously demonstrated.

The authors conclude ‘The results of this study provide strong evidence that adherence to a healthy lifestyle….is associated with a slower rate of memory decline. Importantly, our study provides evidence that these effects also include individuals with the APOE ε4 allele.’

On a similar theme, healthy lifestyle factors predicted a longer life expectancy in participants of the Chicago Health and Aging project and these extra years were more likely to be lived free of Alzheimer’s dementia compared to those participants with unfavourable lifestyle factors.

Type 2 diabetes is a key risk factor for developing dementia, yet even this risk can be modified through adherence to healthy lifestyle habits. A report from the UK biobank study assessed 7 healthy lifestyle factors in people living with type 2 diabetes: no current smoking, moderate alcohol consumption, regular physical activity, healthy diet, adequate sleep duration, less sedentary behaviour, and frequent social contact. After more than 12 years of follow-up, the results shows that participants with the healthiest lifestyle factors reduced their risk of developing dementia by more than 50% compared to participants who were not following these healthy habits.

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LIFESTYLE FACTORS IN PEOPLE WITH HIGH BLOOD PRESSURE: Hypertension, or high blood pressure, is a leading risk factor for premature death and disability globally. Lifestyle factors are crucial for preventing, treating and managing the condition. It is good to see from this study from China that even if you have a diagnosis of high blood pressure you can significantly impact the risk of early death by adopting healthy lifestyle habits.

This cohort study included 14, 392 individuals with hypertension. The unique aspect of the study is that researchers examined the combined association of anti-hypertensive medication and lifestyle with mortality risk among participants with hypertension. Lifestyle factors assessed included BMI, smoking status, diet, physical activity, and sleep duration (optimal 6–8 hours). Diet assessment was based on 3 food components. Participants were assigned 1 point for each if they consumed vegetables at least twice a day, fruits at least once a day, or meat less than once a day.

During the 7.3 years of follow up the results showed that compared to participants not on anti-hypertensive medication and following an unhealthy lifestyle, those participants using anti-hypertensive medication and following a healthy lifestyle had the lowest risk of dying from any cause (68% reduction in risk), cardiovascular disease (67% reduction) and cancer (70% reduction). There were benefits seen for a healthy lifestyle in participants who were not taking anti-hypertensive medications but no reduction in mortality for those taking medication with an unhealthy lifestyle. There was a dose-response in that the greater the adherence to a healthy lifestyle the greater the benefit. Improvement in lifestyle after a diagnosis of hypertension was also significantly associated with lower risk of all-cause and cause-specific mortality

The authors conclude ‘adherence to healthy lifestyle and antihypertensive medication treatment was associated with lower risk of all-cause, cardiovascular, and cancer mortality. Improvement in lifestyle after hypertension diagnosis was also associated with significantly lower risk of mortality’.

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REDUCING THE RISK OF TYPE 2 DIABETES: There is a rising incidence of diabetes in pregnancy (gestational diabetes-GD) which carries an elevated risk of type 2 diabetes later in life and also increases the risk of pregnancy complications.

This study reports pretty remarkable data on lifestyle factors and future risk of type 2 diabetes in 4275 individuals with a history of GD. Five modifiable risk factors were assessed, including not being overweight or obese, high-quality diet (top two fifths of the modified Alternate Healthy Eating Index), regular exercise (≥150 min/week of moderate intensity or ≥75 min/week of vigorous intensity), moderate alcohol consumption (5.0–14.9 g/day), and no current smoking.

During the 28 years of follow up, 21.6% (924 women) developed GD. The results showed that those individuals most adherent to all 5 healthy lifestyle factors reduced their risk of type 2 diabetes by 92%. Each incremental increase in healthy habits was associated with a reduction in risk. These associations were seen even among individuals who were overweight/obese or were at greater genetic susceptibility.

The authors conclude ‘This study highlights the important public health opportunity for the prevention of type 2 diabetes in this high risk population

With one in 10 people over the age of 40 in the UK having a diagnosis of type 2 diabetes, it seems crucial to implement these preventative strategies as a priority.

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HEALTHY LIFESTYLES, CANCER AND CARDIOMETABOLIC DISEASE: Not only does underlying chronic illness increase the risk of cancer, but there is an increased risk of cardiometabolic disease after a diagnosis of cancer. This makes lifestyle interventions for cancer survivorship increasingly important.

This paper reports finding from the UK biobank study and examines the impact of a healthy lifestyle on the risk for cardiovascular disease (CVD) and type 2 diabetes (T2D) before and after the onset of cancer. Two sub-groups were included. A cancer-free cohort of 397,136 individuals in the general population and a cancer-prevalent cohort of 35,564 individuals with cancer. All participants were aged 40 to 70 years, free of CVD and T2D at recruitment and then followed for median of 14 years. The healthy lifestyle index (HLI)was made up of 5 cardiometabolic disease–related healthy behaviours (smoking status, physical activity, diet, alcohol consumption, and sleep duration). If participants met the criteria for each healthy habit they received a score of 1 and if not a score of 0, so a maximum score of 5 could be obtained. A healthy diet was high in fruits, vegetables, whole grains, refined grains, fish and low in unprocessed meat and processed meat.

In the cancer-free cohort 40,097 individuals (10.1%) developed cancer during follow-up. Each 1-point increment in HLI was associated with an 8% lower risk of developing cancer. A 1-point increment in HLI was also significantly associated with a 10% lower risk for developing CVD in patients diagnosed with cancer and a 12% lower risk in those free of cancer. Each additional healthy lifestyle factor had a 17%-26% reduction in risk of death during follow up, with smoking having the strongest negative impact. A 1-point increment in HLI was also associated with a 19% reduction in risk of T2D and a 16% reduction in T2D following a cancer diagnosis.

In the cancer cohort, cancer survivors with 5 healthy lifestyle factors had a 44% reduction in the risk of developing CVD and 38% reduction in the risk of T2D. A 1-point increment in HLI was associated with risk reductions of 10% and 13% in developing CVD and T2D, respectively.

Overall the findings confirm the importance of healthy lifestyle habits for prevention of cancer, CVD and T2D and also the benefits of these healthy habits after a diagnosis of cancer when the risk of chronic conditions is even higher.

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LIFESTYLE INTERVENTION FOR RHEUMATOID ARTHRITIS: Randomised studies are the holy grail of medical research. Nutrition interventions are notoriously difficult to carry out, so these studies are in general small and of short duration. However, they play an important part in providing corroborative evidence for the results shown in observational studies.

There is plenty of evidence that healthy diet patterns, high in plant-based foods, reduce the risk of developing rheumatoid arthritis and may be beneficial for management of the condition. Over the decades there have been non-randomised dietary interventions of vegetarian and vegan diets with or without a period of fasting or other food eliminations. More recently, researchers at PCRM conducted a randomised, crossover study over 16 weeks of a low fat, healthy vegan diet, including elimination and reintroduction of certain trigger foods and demonstrated benefit in symptoms.

The current study is a well designed, assessor-blinded, randomised 16-week lifestyle intervention of a whole food plant-based diet, physical activity and stress management in people with mild to moderate rheumatoid arthritis. Disease activity was measured using the DAS18 score (disease activity score based on 18 joints). The control group received usual care. Medication was kept stable 3 months before and during the trial whenever possible.

The results showed that compared to the control group (n=37), the intervention group (n=40) had significant improvement in disease activity and metabolic health with reductions in body weight and body fat, HbA1C and LDL-cholesterol. Depression, fatigue, pain interference and physical function did not change. Although there were reductions in markers of inflammation (ESR and CRP) in the intervention group, these changes were no statistically significant. As expected, those participants who made the most changes had the greater benefit. There was demonstrable improvement in diet quality in the intervention group, however it is not possible to know which part of the intervention was responsible for the improvements seen.

To take account of the short duration of this study, the control group will be offered the intervention after the trial, and researchers will follow all participants in a 2-year observational extension study including cost effectiveness, body composition, bone mineral density, critical nutrients and a medication-tapering protocol for patients in remission. We look forward to the results.

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