Review of the plant-based nutrition and lifestyle medicine news July 2024
This month I discuss cancer, gout, physical activity & brain health, benefits of the planetary health diet for physical & mental health, industry influence and a long awaited study on olive oil.
Proportion and number of cancer cases and deaths attributable to potentially modifiable risk factors in the United States, 2019
This study evaluates the impact of potentially modifiable risk factors on cancer incidence and mortality in the United States (US) for the year 2019. The main objective was to quantify the proportion and number of cancer cases and deaths attributed to various risk factors that individuals have the power to change or avoid. The risk factors considered included cigarette smoking; second‐hand smoke; excess body weight; alcohol consumption; consumption of red and processed meat; low consumption of fruits and vegetables, dietary fibre, and calcium; physical inactivity; ultraviolet radiation; and seven carcinogenic infections.
Overall, the study found that approximately 40% of cancer cases and 45.5% of cancer deaths in adults aged 30 and older were attributable to the evaluated risk factors. This translates to around 713,340 cancer cases and 273,470 cancer deaths.
Major Risk Factors:
The primary risk factors contributing to cancer incidence and mortality included cigarette smoking, excess body weight, alcohol consumption, physical inactivity, and dietary factors.
Cigarette Smoking: The leading cause, responsible for 19% of cancer cases and 28.8% of cancer deaths.
Excess Body Weight: Accounted for 7.8% of cancer cases and 6.5% of cancer deaths.
Alcohol Consumption: Contributed to 5.6% of cancer cases and 4.0% of cancer deaths. Approximately half of all oral cavity and pharyngeal cancers in men and around a quarter of oral cavity, oesophageal, and pharyngeal cancers in women were attributable to alcohol consumption. However, female breast cancer had the largest number of attributable cases in terms of absolute numbers followed by colorectal cancer in both men and women.
Dietary Factors: Low consumption of fruits and vegetables, dietary fibre, and dietary calcium, combined with high consumption of red and processed meats, resulted in 4.2% of cancer cases and 4.3% of cancer deaths. By cancer type, the proportion of colorectal cancer cases attributable to dietary factors ranged from 4.2% for low dietary calcium, to 7.3% for red meat, to 10.5% for low dietary fibre, and to 12.8% for processed meat consumption. Low fruit and vegetable consumption was associated with 30.7% of oral cavity, pharyngeal, oesophageal, and laryngeal cancers, with oral cavity cancer having the largest number of attributable cases.
Physical Inactivity: Linked to 2.9% of cancer cases and 2.2% of cancer deaths.
Other Notable Risk Factors:
Infections: Accounted for 3.0% of cancer cases and 3.3% of cancer deaths.
Ultraviolet Radiation: Linked to 4.7% of cancer cases and 1.5% of cancer deaths.
Environmental and Occupational Exposures: Contributed to a smaller yet significant proportion of cancer cases and deaths.
Although cigarette smoking remains the leading cause of cancer cases and deaths. However, the combination of excess body weight, alcohol consumption, dietary factors, and physical inactivity contributed to the largest proportion of all cancer cases in women (nearly a quarter of all cases) and was second only to tobacco smoking in men (one sixth of all cases). These
four combined risk factors also contributed to the second highest proportion of cancer deaths in both sexes, i.e., nearly one fifth of all cancer deaths in men and a quarter of all cancer deaths in women
Differences by Sex:
The study observed differences in the impact of these risk factors between men and women. For example, men had a higher proportion of cancers attributable to smoking, whereas women had a higher proportion attributable to excess body weight.
Changes Over Time:
Compared to a previous study conducted for 2014, there was a slight decrease in the proportion of cancer cases attributable to these risk factors (from 42% to 40%). However, the absolute number of attributable cancer cases increased due to population growth and aging.
Policy Implications:
The findings highlight the critical need for public health interventions and policies aimed at reducing exposure to these modifiable risk factors. Efforts to reduce smoking, promote healthy eating and physical activity, and control alcohol consumption could significantly lower cancer incidence and mortality rates.
I sometimes despair of my profession and the medical field in general that prioritises cancer screening, diagnostics and treatments over cancer prevention strategies. Of course we do need advancements in all aspects of cancer care, but it seems to be that public health interventions would have a greater impact and potentially reduce health inequalities in general. It is good to see that the WHO has published its first guideline on smoking cessation. Of note, not all the medications suggested are available in every country. The UK has a smoking cessation campaign called Swap to Stop, where smokers are supported to swap cigarettes for vapes. Although this may be supported by evidence, it is very sad that the same companies that have caused such damage with cigarette sales are now benefiting through the sales of vapes.
Adherence to Healthy and Unhealthy Plant-Based Diets and the Risk of Gout
My favourite diet assessment score, the plant-based diet index, has been used in this study that investigates the relationship between adherence to different types of plant-based diets and the risk of developing gout. It differentiates between healthy plant-based diets (hPDI) and unhealthy plant-based diets (uPDI) and assesses their impact on gout incidence.
The study included 122, 679 participants from two large prospective cohorts, the Nurses' Health Study (NHS) and Health Professionals Follow-Up Study (HPFS), who have been followed for over 30 years. Diets were assessed using food frequency questionnaires, and plant-based diets were scored based on healthy and unhealthy components. Incident gout cases were self-reported and confirmed using the American College of Rheumatology criteria.
The analysis showed that higher adherence to hPDI was associated with a lower risk of gout. Participants in the highest quintile of hPDI had a 21% reduced risk compared to those in the lowest quintile. In contract, higher adherence to an uPDI was associated with an increased risk of gout. Participants in the highest quintile of uPDI had a 17% higher risk compared to those in the lowest quintile.
Regarding individual foods, whole grains, tea and coffee consumption and dairy consumption appeared protective. Consumption of fish, sugar-sweetened beverages (SSBs) and fruit juices was associated with an increased risk of gout.
The reason for these findings may be the impact of certain foods on blood urate levels. For example, dairy consumption is associated with lower urate levels as is vitamin C, due to its effect of increasing urate excretion. The impact of fibre-rich foods on lowering inflammation may also explain some of the benefits. It is unusual not to find higher meat consumption associated with a higher risk, since purine-rich animal foods are associated higher urate levels. Fish also has higher purine content than most plant foods and thus may explain the findings of this study. Higher fructose consumption also increases urate levels and thus may explain the association with higher intakes of SSBs and fruit juices.
Overall, the study's findings suggest that the quality of plant-based diets matters significantly in relation to gout risk. A diet rich in healthy plant foods like fruits, vegetables, legumes, and whole grains is beneficial, whereas a diet high in unhealthy plant foods like sugary beverages and refined grains increases the risk. However, it does not tell us anything about a fully plant-based diet as these participants were all consuming some animal-sourced foods.
This study adds to the growing evidence for eating a healthy plant-based diet. Prior studies using the plant-based diet index to analyse dietary data have shown significant benefits for a number of conditions. The table below with references is from a presentation I gave recently showing the reduction in risk of various conditions and all-cause mortality for people consuming a healthy plant-based diet. This review paper summarises all the data on the plant-based diet index and associations with health outcomes.
A Randomized Crossover Trial on Cardiometabolic Effects of Extra Virgin Olive Oil Within a Whole-Food Plant-Based Vegan Diet
We may finally be able to answer the question, at least in part, around the health impacts of extra virgin olive oil (EVOO) as part of a whole food plant-based diet (WFPBD). This study investigated the cardiometabolic effects of consuming different amounts of EVOO within a WFPBD (plant-exclusive/vegan). It aimed to address the optimal quantity of dietary fat, particularly EVOO, in reducing cardiovascular disease (CVD) risk factors.
The study design was a randomised, crossover trial, including 40 adults with ≥5% risk of CVD. The intervention was four weeks of a WFPB diet with high (4 tablespoons/day) or low (<1 teaspoon/day) amounts of EVOO. There was a one week washout period and then the groups crossed over to the alternate group. Participants attended weekly virtual cooking classes and were provided with EVOO and gift cards for grocery purchases. Participants were asked to abstain from eating any animal sourced foods and heavily processed or refined food items containing refined grains, added sugars, or oils. The EVOO was meant to be consumed raw. Participants also took a vitamin B12 supplement.
The primary outcome of the study was change in low-density lipoprotein cholesterol (LDL-C) levels compared to baseline. Secondary outcomes included changes in total cholesterol, apolipoprotein B, high-density lipoprotein cholesterol (HDL-C), glucose, and high-sensitivity C-reactive protein (hs-CRP).
The result showed that fat intake was 48% of energy during the high EVOO phase and 32% during the low EVOO phase. Both diet patterns resulted in comparable reductions in LDL-C, total cholesterol, apolipoprotein B, HDL-C, glucose, and hs-CRP. However, there was an impact of diet sequence with greater reductions in LDL-C, total cholesterol, HDL-cholesterol, apolipoprotein B and glucose with the low EVOO diet. Body weight decreased in both diet groups, with a greater benefit from the low EVOO phase.
Overall the study confirms the benefits of a WFPBD for improving cardiometabolic risk factors. In addition, it suggests that keeping EVOO intakes at very low/negligible levels may further improve blood lipid profile and body weight, which the authors propose is due to further removal of dietary saturated fat found at low levels in EVOO, but could also be due to improved weight loss.
Things to note in this study:
The study is small and of short duration and cannot tell us about specific health outcomes, just changes in biomarkers that predict for CVD.
This wasn’t a low fat study per se, since the low EVOO still have a fat intake of 32% of total energy, but coming from whole plant sources: avocados, nuts, seeds, olives.
The study cannot fully discount the fact that differences in body weight may have been the reason for better lipid profile in the low EVOO group. The low-EVOO group consumed around 400 fewer calories per day, which will have supported the greater weight loss.
Fibre intake seemed on the low side for a WFPBD, around 30g/d with only 0.4 cups of legumes consumed a day and around 10-14% of energy coming from protein. Thus, it may be that participants should have be encouraged to eat more protein-rich plant-based foods.
Although 21 of the 40 participants were already on lipid lowering drugs, there was additional benefits for dietary interventions.
Overall, a very useful addition to the WFPBD literature, allowing us to personalise plant-based interventions depending on health goals and preferences. Read my updated article on the topic here.
Effects of Cocoa Consumption on Cardiometabolic Risk Markers: Meta-Analysis of Randomized Controlled Trials
This study evaluates the long-term effects of cocoa consumption on various cardiometabolic risk markers by conducting a systematic review and meta-analysis of randomised controlled trials (RCTs). Adults aged 18 and above were included. Some were healthy and others with conditions such as hypertension, type 2 diabetes, dyslipidaemia, overweight/obesity, or myocardial infarction/stroke.
Thirty-one studies with 1986 participants were included. The intervention was consumption of cocoa-extract supplements or dark chocolate with ≥70% cocoa for at least four weeks. The comparison or control group was placebo or white/milk chocolate with <70% cocoa. The outcomes reviewed included: Body weight, BMI, waist/abdominal circumference, lipid profile (total cholesterol, LDL-C, triglycerides, HDL-C), fasting blood glucose, HbA1c, systolic blood pressure (SBP), and diastolic blood pressure (DBP).
Key findings
Anthropometric Measurements:
Cocoa consumption did not significantly reduce body weight, BMI, or waist circumference.
A slight reduction in abdominal circumference was observed but not consistent across all studies.
Lipid Profile:
Total cholesterol decreased by 8.35 mg/dL.
LDL-c reduced by 9.47 mg/dL.
No significant reduction in triglycerides and HDL-c levels.
Glycaemic Profile:
Fasting blood glucose decreased by 4.91 mg/dL.
No significant effect on HbA1c levels.
Blood Pressure:
SBP decreased by 2.52 mmHg.
DBP reduced by 1.58 mmHg.
The reduction in blood pressure was more pronounced with higher polyphenol intake.
The quality of evidence was rated as "moderate" using the GRADE system.
Overall, the authors concluded that cocoa consumption (>70% chocolate) had a protective effect on major cardiometabolic risk markers, including reductions in total cholesterol, LDL-c, fasting blood glucose, SBP, and DBP, contributing to cardiovascular risk reduction. However, its impact on body weight, BMI, and waist circumference remain inconclusive.
These benefits are likely to be due to the high polyphenol content of cocoa. The study also showed that participants who were ‘unhealthy’ derived a greater benefits from cocoa consumption compared with otherwise ‘healthy’ individuals. The ‘doses’ of chocolate used in these studies was 10-40g daily.
Another meta-analysis and systematic review of controlled studies found that cocoa consumption lowered markers of inflammation and oxidative stress. Overall, these two studies suggest that dark chocolate can be healthy addition to the diet.
The Role of Physical Exercise in Cognitive Preservation: A Systematic Review
This systematic review aimed to examine the impact of physical exercise on cognitive preservation in older adults, focusing on the types, intensity, and duration of exercise interventions and their specific cognitive benefits.
17 randomised controlled trials (RCTs) were included, involving 1986 older adults (aged 50 and above) with or without cognitive impairment. The interventions included aerobic, strength, or multicomponent exercise regimens with cognitive outcomes measured using standardized tests. The duration of interventions ranged from 4 to 24 weeks, and types of exercises varied widely. Most studies focused on aerobic exercise, with fewer studies examining strength training or multicomponent programs.
Cognitive benefits were observed in various domains, including memory, executive function, and overall cognitive performance. The magnitude of benefits varied by exercise type and intensity. Aerobic exercise consistently showed improvements in cognitive function, particularly in memory and executive function. The intensity of aerobic exercise did not show a clear dose-response relationship. There were mixed results for strength training with some studies reporting improvements in cognitive function, while others did not find significant effects. Combining aerobic and strength training with social interaction and cognitive tasks showed promise in improving cognitive outcomes, though evidence was limited. The most beneficial effects were seen in studies that included cognitively intact participants or those with mild cognitive impairment, suggesting that physical exercise may have the greatest impact before people reach the stage of active dementia. Effects of physical exercise diminished after study interventions ended, and it remains unclear if exercise might prevent progression if maintained over time as long-term exercise trials have not yet been conducted.
The benefits of physical activity are thought to be due to increased cerebral blood flow, neurogenesis, and reduction of neuroinflammation. Exercise may also enhance brain plasticity and connectivity.
Overall, the results support the use of physical activity and exercise for prevention of cognitive decline along with other healthy lifestyle habits. Last month I covered the ground-breaking new study from Dr Dean Ornish, which suggested his intensive multi-component lifestyle intervention may be able to arrest and possibly even improve function in people with early stages of dementia. The study was covered extensively in the US media.
Benefits of the planetary health diet for physical and mental health and well-being.
The planetary health diet (PHD) is the name given to the eating pattern devised by authors of the Eat-Lancet commission who were tasked with devising a diet that would not only improve health outcomes, but keep the food system within planetary boundaries. The diet is predominantly plant-based with recommendations to derive more that 85% of energy from fruit, vegetables, whole grains beans, nuts and seeds, whilst minimising or avoiding animal-sources foods and sugar-sweetened beverages. The only animal food considered to be health promoting is fish with an allowance of 2 portions a week.
Two analyses using data from participants including in the UK Biobank study have recently been published. The first is called ‘Adherence to a planetary health diet, genetic susceptibility, and incident cardiovascular disease: a prospective cohort study from the UK Biobank’. The study investigated the relationship between adherence to a PHD, genetic susceptibility, and the risk of developing cardiovascular diseases (CVD). The study included 114,165 participants who completed at least two 24-h dietary recalls and were followed for a median of almost 10 years. Genetic risk was evaluated using the polygenic risk score.
The results showed that high adherence to the PHD was associated with a significantly reduced risk of total cardiovascular disease, ischaemic heart disease, atrial fibrillation and heart failure. This association was consistent regardless of the participants' genetic susceptibility to CVD. Specific foods associated with changes in risk included total grains, which lowered the risk of CVDs, whilst red meat and high intake of sugar increased the risk. The results suggested that 8.8% of the CVD cases would be prevented if all participants in the current study had the highest adherence to PHD. Its worth noting though that even those with the highest adherence in this study were only consuming 53.7g/day of legumes, 13.9g/day of nuts while still consuming red meat and around 30g of saturated fat per day. So quite some room left for optimising the diet.
Similarly, another study called Adherence to the EAT-lancet diet and incident depression and anxiety investigated the relationship between adherence to the EAT-Lancet PHD and the risk of developing depression and anxiety in the same cohort. 180,446 participants were included and followed for more than 11 years. Higher adherence to the PHD was associated with a reduced risk of incident depression and anxiety with a dose-response observed. Associations between adherence to the PHD and incident depression and anxiety were more pronounced in those with greater socioeconomic deprivation. Specific foods that were associated with the observed benefits included fruit, vegetables and fish consumption.
Key mechanisms by which the PHD may improve health outcomes include a healthier gut microbiome, lower levels of inflammation, improved cardiometabolic risk factors, including body weight, blood pressure, blood lipids and glucose regulation.
Both these papers suggest that a plant-predominant diet, which will help us meet climate and nature target has benefits for both physical and mental health and wellbeing. This seems a win-win situation. Thus country-based dietary guidelines should all use the recommendations of the EAT-Lancet commission to construct culturally-relevant food based guidelines that are centred around healthy plant-based foods.
The New Merchants of Doubt: How Big Meat and Dairy Avoid Climate Action
This report reveals how Big Meat and Dairy companies are employing tactics similar to those used by the tobacco and fossil fuel industries to delay, distract, and derail necessary actions on food system transformation. These industries contribute significantly to greenhouse gas emissions, especially methane, which needs to be drastically cut to meet the targets set by the Paris Agreement. The report divides these tactics into three main strategies: distract, delay, and derail.
Distract:
Companies use greenwashing tactics to present their products as environmentally friendly and essential for a healthy diet.
They target younger generations through social media campaigns and misleading advertising to maintain high levels of meat and dairy consumption.
The industry emphasises weak net-zero targets and voluntary commitments, creating a false sense of progress while environmental impacts worsen.
Delay:
Companies promote voluntary actions and technological fixes that are often ineffective, slowing down regulatory measures.
They invest minimally in low-carbon solutions compared to their spending on advertising and lobbying.
The industry lobbies for policies that rely on incentives rather than mandatory regulations, benefiting large corporations at the expense of meaningful climate action.
Derail:
Big Meat and Dairy spend millions on political donations and lobbying to influence policy and prevent regulations that could harm their interests.
The report highlights numerous examples of conflicts of interest and revolving doors between industry and regulatory bodies.
Key policies aimed at reducing emissions and promoting sustainable practices are weakened or abandoned due to industry influence.
Key Findings
Food systems contribute about a third of global greenhouse gas emissions, with animal agriculture responsible for 60% of this.
Significant reductions in methane emissions and a shift to plant-based diets are crucial for staying within the 1.5-degree temperature increase target.
Despite their climate impact, meat and dairy corporations face fewer regulations compared to other sectors due to successful lobbying efforts.
The industry’s tactics have led to delayed action on climate policies, with an overreliance on voluntary measures and technical fixes that lack efficacy.
Detailed analysis of the influence of 22 major meat and dairy companies shows extensive lobbying and misleading public relations campaigns.
The report calls for greater scrutiny and regulation of the meat and dairy industries, akin to the oversight faced by the tobacco and fossil fuel industries. It emphasises the need for mandatory climate action, significant reductions in meat and dairy consumption, and increased support for sustainable and plant-based alternatives to mitigate the climate crisis.
Recommendations
For Governments: Implement strict regulations and reduce subsidies that support the status quo of animal agriculture.
For Companies: Set and adhere to science-based targets for emissions reductions, and shift investments towards genuinely sustainable practices.
For Consumers: Increase awareness of the environmental impact of meat and dairy consumption and support plant-based alternatives.
The other major issues affecting the food system is the concentration of power amongst a handful of companies that control the global food supply. This article explains more and highlights that the imbalance of power is leaving large number of people globally in hunger and food insecurity despite there being plenty of food to feed us all. In addition, a new report from researchers at Exeter University in the UK, warns us again that intensive farming of animals for food increases the risk of new infections with pandemic potential.
This corporate hold over the food system continues to cause further deterioration in diet quality amongst adults and children. A recent analysis shows that ultra-processed food consumption in UK adolescents continues to account for more than 60% of total energy intake with higher consumption among adolescents from lower socioeconomic backgrounds.
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Wonderful review as always, thank you Shireen