Review of the plant-based lifestyle medicine news March 2024

This month I cover the benefits of sleep, some good news for bone health and those with arthritis, the role of metabolic syndrome in cancer risk, benefits of herbs and spices and more.

SLEEP DURATION AND TYPE 2 DIABETES: Dietary risk factors are responsible for 70% of the risk of developing type 2 diabetes (T2D). However all pillars of lifestyle medicine are important to maximise risk reduction.

This study analysed data from participants of the UK Biobank study. The aim was to analyse the association between sleep duration, healthy dietary patterns and the risk of T2D. Data from 247, 867 participants, aged 38 to 71 years and mostly White European was included. Sleep duration, including naps, was reported by participants. Participants who reported a daily sleep duration of 7 to 8 hours were categorised as having normal sleep duration. Short sleep duration was classified as mild short sleep (6 hours), moderate short sleep (5 hours), and extreme short sleep (3–4 hours). Healthy eating included criteria such as fewer than 2 servings of unprocessed red meat per week (67.3%), fewer than 2 servings of processed meat per week (39.2%), 4 or more tablespoons of vegetables per day (64.8%), 2 or more pieces of fruit per day (72.7%), and 2 or more servings of fish products per week (52.3%). Each healthy dietary behaviour scored 1 point, resulting in a healthy diet score ranging from 0 (unhealthiest) to 5 (healthiest).

The analysis showed that 75.5% of participants reported normal sleep duration, 19.8% reported mild short sleep duration, 3.9% reported moderate short sleep duration, and 0.8% reported extreme short sleep duration. Additionally, 1.5% attained a healthy diet score of 0, 7.4% scored 1, 17.6% scored 2, 27.5% scored 3, 29.0% scored 4, and 17.0% scored 5 (defined as the healthiest dietary pattern).

During the median 12.5 years of follow up 7905 participants (3.2%) were diagnosed with T2D. Compared to participants reporting normal sleep duration (reference group), those who reported sleep durations of less than 6 hours per night had a greater risk of developing T2D (16% increased risk for 5 hours and 41% increased risk for 3–4 hours). There was no increased risk for those reporting 6 hours of sleep. As expected, a healthy diet score of 5 or 4 was associated with a lower 25% and 18% lower risk of T2D, respectively. The analysis did not find an interaction between sleep duration and diet quality. This implies that sleep duration is an independent risk factor for the development of T2D that cannot be overcome with a healthy diet.

Lack of sleep can increase risk of T2D by impairing our cells response to insulin, increasing the activity of the sympathetic nervous system, altering skeletal muscle metabolism and negatively affected the gut microbiome. Prioritising all pillars of lifestyle medicine is important for prevention of type 2 diabetes.

METABOLIC SYNDROME AND RISK OF CANCER: I have always thought that we overlook the impact of underling chronic conditions, such as type 2 diabetes, cardiovascular disease, liver and kidney diseases on the risk of subsequent cancers. In fact, up to a third of the risk of developing cancer may be associated with these underlying conditions. It is useful to find a study investigating and highlighting the negative impact of metabolic syndrome (MetS) on cancer risk, given the unique opportunity to support prevention.

MetS encompasses conditions such as high blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol and triglyceride levels. This group of conditions often occur together and increase the risk of heart disease, stroke, and type 2 diabetes. Although we already know these conditions increase the risk of cancer, this new study specifically examines dynamic changes in MetS in a large prospective cohort study conducted in China.

The study included 44,115 participants with at least 3 assessments performed during the follow-up period of 9.4 years. 79% of participants were men with a mean age of 49 years. The analysis examined four trajectories of metabolic syndrome 1) The low stable pattern consisting of 4657 participants (10.56%) who maintained low MetS scores. 2) The moderate‐low pattern included 18,018 participants (40.8%) who consistently maintained moderate to low MetS scores. 3) The moderate‐high pattern included 18,288 participants (41.46%) who consistently maintained moderate to high MetS scores. The elevated‐increasing pattern included 3152 participants (7.14%), who initially had elevated MetS scores that increased over time.

The results showed that compared to the low‐stable pattern, the elevated‐increasing trajectory pattern was associated with a 27% elevated risk of overall cancer as well as specific types including breast cancer (111% increased risk), endometrial cancer (233%), kidney cancer (352%) colorectal cancer (154%), and liver cancer (61%). In participants with elevated CRP (marker of inflammation) there was a significant increase in risks of breast, endometrial, colorectal, and liver cancers. However, even if CRP levels were not elevated, people with the elevated‐increasing trajectory pattern had an increased risk of kidney cancer.

Overall, the results indicate that worsening of MetS and its components over time significantly increase the risk of subsequent cancer with some of this risk due to elevated levels of inflammation. This highlights the importance of preventing and treating MetS and here a plant-based lifestyle approach can have a unique impact.

There is absolutely no doubt about the power of healthy lifestyle habits for preventing cardiometabolic conditions as shown by extensive prior literature, including cardiovascular disease and type 2 diabetes as well as for preventing cancer.

LIFESTYLE INTERVENTION FOR ARTHRITIS: This is a very exciting publication 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.

The research team have now 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.

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.

PLANT-BASED DIETS AND HIP FRACTURE: This is a very useful paper to be aware of given the concerns around increased risk of fracture particularly in women following a meat-free diet. Once again, it seems that diet quality is paramount. The study reports data from the Nurses’ Health Study conducted by researchers from Harvard University where the plant-based diet index was developed.

The study included 70,285 postmenopausal women who participated in the US Nurses’ Health Study from 1984 to 2014. Hip fractures were self-reported on biennial questionnaires. Diet was assessed every 4 years using a validated semi-quantitative food frequency questionnaire. Plant-based diet quality was assessed using two previously established indices: the healthful Plant-Based Diet Index (hPDI), for which healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, vegetable oils, and tea or coffee) received positive scores, whereas less healthy plant foods (fruit juices, sweetened beverages, refined grains, potatoes, and sweets or desserts) and animal foods received reversed scores; and the unhealthful Plant-Based Diet Index (uPDI), for which positive scores were given to less healthy plant foods and reversed scores to healthy plant and animal foods.

The results showed that during the 30-year follow-up period, adherence to a plant-based diet, healthy and unhealthy versions, was not associated with the risk of hip fracture. Even when yogurt, fish and poultry intake were scored positively in the hPDI, the results were unchanged. However, comparing lowest to highest quintiles of PDI scores from the most recent dietary intake data collected, a hPDI was associated with 21% lower risk of fracture, whereas the most recent intake of an uPDI was associated with 28%higher risk of fracture. The authors conclude ‘Findings of this cohort study suggest that following a plant-based diet over time appears safe regarding the risk of hip fracture’.

Points worthy of note are that people in this study were neither vegan or vegetarian and so animal-sourced foods were still consumed to varying degrees by the participants. Calcium intake was highest among individuals with the greatest adherence to hPDI (1129mg of calcium per day), even though dairy consumption was lower but with greater use of calcium supplementation. Although protein intake is considered important for bone health, this study did not find an association with fracture risk for any particular food group, including those that are higher in protein.

Overall, this study provides some reassurance that a high-quality plant-based diet can support bone health, whilst we should be also emphasising an overall healthy lifestyle that includes both aerobic and strength exercises. You can read my updated article on the topic here.

IMPACT OF HERBS AND SPICES ON BLOOD SUGAR: We know that herbs and spices used in cooking all have unique properties and contain numerous bioactive compounds, many of which demonstrate measurable health benefits.

This study specifically brings together the available data on herbs and spices used within the Mediterranean diet, such as black cumin, clove, parsley, saffron, thyme, ginger, black pepper, rosemary, turmeric, basil, oregano, and cinnamon, and their impact on blood sugar control in people with type 2 diabetes. The study included 77 articles in the systematic review, and out of those articles, 45 were included in the quantitative synthesis (meta-analysis).

It is quite a detailed paper which is available free online. Overall, the results showed that cinnamon, turmeric, ginger, black cumin, and saffron significantly decreased fasting glucose in people with type 2 diabetes. Black cumin achieved the greatest decrease in the fasting glucose, followed by cinnamon and ginger. However, only ginger and black cumin reported a significant improvement in HbA1c, and only cinnamon and ginger showed a significant decrease in the insulin concentration. Of note, ginger appears to be the unique one out of the analysed aromatic herbs, producing a significant decrease in the three outcomes examined, fasting glucose, HbA1c, and insulin.

Herbs and spices are key in a whole food plant-based diet and count towards your goal of 30 different plant types per week that appears useful for promoting better gut health. So get going and use these in your cooking.

LONG-TERM CONSUMPTION OF 6 DIFFERENT BEVERAGES: I mostly concentrate on health impacts of food, but what we drink is also important. This new study assessed the long-term intake of 6 beverages: sugar-sweetened beverages (SSBs), artificially sweetened beverages (ASBs), tea, coffee, fruit juice, energy drinks and alcohol and their association with cardiovascular mortality (dying from cardiovascular diseases such as coronary artery disease (CAD), cerebrovascular disease, and heart failure). Twenty studies were included in the systematic review and meta-analysis, and they had all assessed the intake of one or more of these beverages at more than one time point during the study follow up. They also investigated sex differences in outcomes.

The results showed that long-term consumption of coffee (>2–6 cups a day) was associated with a 37% reduction in CVD mortality in men but there was only a non-significant trend to a benefit (22% reduction in risk) in women. Tea consumption was associated with a 19% reduction in risk in both men and women. Alcohol consumption was associated with a 32% high risk of overall CVD mortality mainly due to a 44% and 126% higher risk of stroke in men and women respectively. SSB consumption was associated with a 31% higher risk of CVD mortality in both sexes, but ASB did not have an impact on health outcomes. There was insufficient data on fruit juice or energy drinks to draw conclusions.

So overall, useful data to be aware of that mainly reinforces the knowledge we already have. Tea and coffee are fine to include as part of a healthy plant-based diet if you enjoy them, but alcohol and SSBs adversely affect health.

SUSTAINABLE DIETS AND MICRONUTRIENT SUFFICIENCY: This is a useful reminder of the how changes in diet composition can change micronutrient intakes. The aim of this review was to evaluate the evidence of effects on intakes and status of selected micronutrients resulting from changes in dietary intakes to reduce environmental impact. Eligible studies had to report individual micronutrient intake and/or status data collected in free-living individuals from the year 2000 onward along with environmental outcomes.

56 studies were included and there is a lot of detail provided in the paper. The image below highlights the main findings. It’s worth noting that for most studies included, 1000mg per day of calcium was considered adequate whereas in the UK our recommendations are for 700mg per day for adults.

Overall, most studies showed that as you move away from meat consumption towards a plant-based diet there will be lower intakes of zinc, vitamins B12, D, and A and iodine and similar or higher intakes of iron and folate. The nutrients identified that were potentially at risk for inadequate intakes as diets become more plant-based were vitamins B12, D and A and zinc and calcium.

I personally don’t think these results are a cause for concern as we know that all diet patterns can be at risk of nutrient inadequacies. This has been highlighted in two recent papers, in adults and in children. In addition, there are favourable attributes to plant-based diets that were not part of the current study including higher intakes of potassium, vitamins C and E and fibre with lower intakes of saturated fat. Another useful reference is a modelling study from France which found that swapping up to 80% of protein-rich foods from animal sources to plant sources would still allow for nutrient sufficiency. We should also note that the authors of the current study found that the available studies on this topic are not sufficiently robust, and more are needed to adequately answer questions on nutrient adequacy on environmental sustainable diets.

It is clear from the available data that if diets are more than 80% plant-based then we do need to consume fortified foods and supplements, paying particular attention to vitamins B12 and D that require supplementation.

Don’t forget to utilise our handy resources, especially the Plant-Based Eatwell Guide and our kids section, which includes information for those planning pregnancy and lactation on a plant-based or vegan diet.

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