The top science papers of 2024 supporting plant-based nutrition
Another year of irrefutable evidence demonstrating the benefits of a whole food plant-based diet for people, planet and the animals.
Photo by Anna Pelzer on Unsplash
The British diet is resulting in considerable harm. The Food Farming and Countryside commission report found that unhealthy diets are resulting in a cost of £268 billion annually from healthcare, social and welfare care costs and productivity losses due to negative impacts on health. This cost is more than the annual budget of the NHS. The report highlights that diets are fibre-deficient due to insufficient intakes of fruits, vegetables and whole grains, whilst we over consume ultra-processed foods. At the same time, several reports highlight how our food system continues to harm our planet and other animals we share the planet with.
Improving lifestyle expectancy (LE) with dietary modification: This study models the impact of dietary modification on LE. Specifically, it aimed to estimate the increase in LE resulting from the transition from typical national dietary patterns to longevity-optimising dietary changes, more feasible dietary modifications, or optimised vegan dietary changes, in China, France, Germany, Iran, Norway, the United Kingdom, and the United States.
This new study showed that shifting from the typical country-based diet to a longevity diet at the age of 40 years increased LE by 6.2 to 9.7 years and shifting to a vegan diet increased LE by 5.2 to 8.7 years. Shifting to a feasible diet resulted in an increased LE of 2–4 years. Once again, consuming more legumes, whole grains and nuts and less red and processed meat resulted in the greatest gains. The slightly greater LE of the longevity diet was as a result of including fish, however the authors note that a vegan diet has benefits that go beyond just individual health. A vegan diet has considerable benefits for planetary health and the animals and also reduces food costs.
For me this study is reassuring as it confirms that an optimised vegan diet has significant longevity benefits compared to the current commonly consumed diet patterns in seven high- and middle-income countries. There is only a small difference in longevity compared to the longevity diet that includes fish that may well be negated by the other positive impacts of a vegan diet.
Plant-based diets improve cardiovascular health and reduce the risk of gastro-intestinal cancers: This huge study brings together all the available data on the impact of vegetarian and vegan diets, termed animal-free and animal-products free diets, on the risk factors associated with the development of cardiometabolic diseases, cancer and their related mortalities. The analysis included 49 studies spanning two decades of research from 1st January 2000 to 31st June 2023. It found that vegetarian and vegan diets (compared to omnivorous diets) are associated with a significantly better lipid profile (lower total and LDL-cholesterol), glycaemic control (lower fasting glucose and HbA1C), body weight/BMI, inflammation (lower C-reactive protein), and lower risk of ischaemic heart disease (15–40% reduction in risk) and cancer (13–20% risk reductions). For cancer risk there is inconsistency in the data with regards cancer types, but there is a more consistent association with lower rates of gastrointestinal cancer for those consuming a meat-free diet. A vegetarian diet is also associated with lower mortality from CVDs, both ischaemic heart disease and stroke (12–29% reduction). There were no studies assessing CVD and cancer mortality in vegans. The impact on HDL-cholesterol and triglycerides, systolic and diastolic blood pressure levels remain variable. Vegetarian diets, but not vegan, also reduce ApoB levels (although we do have this study from 2023 that does show benefits of a vegan diet on ApoB levels). No difference in the risk of developing gestational diabetes and hypertension were reported in pregnant women following vegetarian diets.
Overall, this study demonstrates the consistency of data supporting the benefits of animal-free diets on cardiovascular risk factors, cardiovascular diseases and cancer. There are more studies conducted in vegetarians than vegans. Diet quality is key when considering the impact of meat-free diets and this might account for some of the variation in results between studies. The authors do warn that there was heterogeneity in the quality of studies included in the analysis and hence we need to be cautious about the interpretation.
Dietary protein and healthy ageing: The optimal intake of protein for healthy ageing continues to be a topic of debate. In general, there seems to be a consensus that higher intakes in older adults are associated with better health outcomes. This 2024 analysis from the Nurses’ Health Study examines the impact of protein intake on healthy ageing as defined as having no impairment of memory or physical function, good mental health and being free from 11 major chronic conditions, including cancer (except for non-melanoma skin cancer), type 2 diabetes, myocardial infarction, coronary artery bypass graft surgery or percutaneous transluminal coronary angioplasty, congestive heart failure, stroke, kidney failure, chronic obstructive pulmonary disease, Parkinson disease, multiple sclerosis, and amyotrophic lateral sclerosis.
The study included 48,762 women who were under the age of 60 years in 1984 and followed until 2016. The analysis assessed healthy ageing between 70–92 years. The results showed that higher intakes of protein were associated with greater odds of healthy ageing. All sources of protein showed this beneficial association. However, when broken down into animal, dairy and plant sources of protein, it was plant protein that was associated with the greatest benefit to both physical and mental health. In substitutions analysis, replacing 3% of calories from saturated (SFA), monounsaturated (MUFA) or polyunsaturated fat (PUFA), or carbohydrates from whole grains or refined sources, with plant protein was associated with a 22% to 58% greater chance of healthy ageing. Replacing animal protein or dairy protein with plant protein was associated with a 38% and 26% greater chance of healthy ageing respectively. In the substitution analyses, researchers observed that animal protein intake was unfavourably associated with the incidence of chronic diseases when compared with calories primarily from carbohydrates (total, refined, or whole grain) or from total fat, SFA, MUFA, or PUFA.
In terms of the amounts of protein being consumed, those in the lowest quintile were consuming 14.2% (57.7g) of energy from protein compared to the highest quintile of intake at 22.5% (89.2g/day). Potential mechanisms proposed by the researchers that may explain these results include that dietary protein (and exercise) activates the mammalian target of rapamycin complex 1 signalling, thereby stimulating muscle protein synthesis, which is associated with improved physical function in older adults. Plant sources of protein come in a healthier package than animal sources and are associated with better cardiometabolic health and lower levels of inflammation.
Overall, this study confirms the results of several others, that higher protein intakes in later life may support better health and longevity with plant sources of protein being superior to animal sources.
Along with data to support consuming more plant protein, we have continued confirmation that eating red and processed meat adversely affects health. People often need reminding that red meat is any flesh from a mammal. This study analysed data from the Million veteran program and included 148,506 participants, mainly men, followed for 3.8 years. Higher intake of total red meat, unprocessed red meat and processed red meat was associated with 18%, 14%, and 29% increased risks of cardiovascular disease, respectively. There was a dose effect with around a 10% increased risk for every 1 serving per day. For fatal CVD, there was a 31% and 59% increase in risk for people consuming the most (>2 servings per day) total and unprocessed red meat compared to those consuming the least (<0.14 servings per day). Processed red meat consumption had a greater negative impact on non-fatal CVD (48% increase in risk). These associations were stronger in African American than in white participants. Replacing 0.5 serving/day of red meat with 0.5 servings/day of nuts, whole grains, and skimmed milk was associated with 14%, 7% and 4% lower risks of CVD, respectively. Overall, the analysis showed that 7.7% of CVD events in this study population could have been potentially prevented if all the participants reduced their red meat consumption to fewer than half a serving per day.
Protein source and risk of type 2 diabetes: This 2024 systematic review and meta-analysis specifically assessed the impact of protein source on the risk of type 2 diabetes. The analysis included 16 prospective cohort studies, involving 615,125 participants and 52,342 cases of type 2 diabetes. The results showed that protein intake from animal sources increased the risk of type 2 diabetes with a dose dependent effect. Participants with the highest intake of animal protein had a 18% increased risk of type 2 diabetes, with every 20g increase associated with a 7% increase in risk. Consumption of plant sources of protein did not show this same effect. Instead, substitution analysis showed that replacing animal with plant protein intake (per each 20g) was associated with a 20% reduction in the risk of type 2 diabetes.
There are numerous potential reasons for these findings. Animal protein has higher levels of branch chain amino acids – leucine, isoleucine and valine – which are associated with insulin resistance and an increased risk of type 2 diabetes. Animal protein comes packages with saturated fat, haem iron, nitrates and nitrites (processed meat) and create higher levels of advanced glycation end products. All of these compounds are associated with higher levels of inflammation and cellular stress and implicated in the development of type 2 diabetes. In contrast, plant proteins are packaged with fibre, numerous phytonutrients and are low in saturated fat. These properties are associated with a healthier gut microbiome, which is very important for glucose regulation, and lower levels of inflammation and cellular stress.
The authors conclude ‘These findings indicate that future dietary guidelines should consider the origin of dietary protein in their recommendations for type 2 diabetes prevention and advise a reduction in consumption of animal protein and an increased intake of plant-based protein sources’.
Interestingly, an observational study that analysed plasma metabolic biomarkers and metabolomic profiles found that increased intake of haem iron is associated with an increased risk of developing type 2 diabetes and is correlated with unfavourable plasma profiles such as insulinaemia, abnormal blood lipids and inflammation.
Another huge analysis of a number of cohorts from around the world has confirmed the association between meat consumption and an increased risk of type 2 diabetes with a dose-related response. Poultry, unprocessed red meat and processed meat consumption all increased the risk (8-15% increased risk) over a 10-year period, with the greatest risk associated with processed meat consumption. Some but not all of this increase in risk was due to the association between meat consumption and higher body mass index. Replacing processed meat with unprocessed red meat or poultry was found to reduce the risk of type 2 diabetes. But replacing unprocessed red meat with poultry did not impact the risk. The authors conclude ‘This study is, to our knowledge, the most comprehensive evidence base to date on the consumption of different types of meat and the risk of developing type 2 diabetes and, together with previous evidence, provides support for public health initiatives to reduce the consumption of meat to improve human health and planetary sustainability.’
Dietary factors and multiple sclerosis (MS): There is growing interest in the role of diet and lifestyle approaches for improving outcomes for people living with MS. I previously wrote about the impact of health habits and I have also dedicated a news review to the topic of diet and MS, which included the publication of our two case histories. We have learnt a lot on the topic of diet and lifestyle for MS from the HOLISM study and this year we have a new analysis from this longitudinal cohort.
The study reported specifically on the impact of dietary factors on fatigue and disability in 839 participants living with MS. The mean age of the participants was 46 years and duration of MS was 7–12 years. In addition to assessing diet quality using the Diet History Questionnaire, specific questions were asked about the consumption of meat and dairy (including capturing information on those that did not consume meat and dairy), omega-3 fats from fish, fish oil or flaxseed oil and use of vitamin D supplementation.
The analysis found that a higher quality diet, consumption of omega-3 fats, vitamin D supplementation and avoidance of meat and dairy consumption were all associated with a reduced risk of progression and lower rates of fatigue and disability.
Diet and lifestyle modification is slowly but surely becoming a key part of management of MS. This has been spearheaded by the international charity, Overcoming MS. Their dietary recommendations are in line with the evidence supporting a plant-based diet with additional omega-3 fats from fish, fish oils or high strength flaxseed oil and vitamin D supplementation. They also pay attention to all pillars of lifestyle medicine.
Plant-based diets and prostate cancer: There are a number of studies demonstrating the benefits of plant-based diets (PBD) for men’s health, especially when it comes to prostate cancer risk. I have summarised the available data in this article.
This 2024 study specifically assesses the impact of a PBD as defined by the plant-based dietary index on progression of prostate cancer once a diagnosis is made. The study included 2062 men from the US enrolled in the Cancer of the Prostate Strategic Urologic Research Endeavor study with biopsy-proven non-metastatic prostate cancer. Diet was assessed at a median of 31.3 month after the diagnosis of prostate cancer and participants were followed for a median of 6.5 years after the dietary assessment.
The results showed that participants most adherent to an overall PBD had a 47% reduction in risk of cancer progression compared to those that were least adherent. Restricting the overall analysis to a healthy PBD did not seem to have an impact, however for those with the most more aggressive type of prostate cancer, adherence to a healthy PBD reduced the risk of progression by 55%.
The authors conclude ‘higher intake of plant foods after prostate cancer diagnosis was associated with lower risk of cancer progression. These findings suggest nutritional assessment and counselling may be recommended to patients with prostate cancer to help establish healthy dietary practices and support well-being and overall health’.
It is interesting to note that even those described as eating a healthy PBD were only consuming 1.1 portions of whole grains, 2.1 portions of fruit, 3.8 portions of vegetables, 0.4 portions of nuts per day and 0.1 portion of legumes per day. This is hardly what we would describe as a healthy PBD. They were, however, eating half the amount of meat, dairy and eggs compared to those least adherent to a plant-based diet.
This additional study investigated the role of plant-based diets for improving quality of life in 3505 men from the Health Professionals Follow-up Study with a diagnosis of non-metastatic prostate cancer. Dietary data were used to calculate the overall and healthy plant-based diet indices. This was correlated with indicators of quality of life measured at a mean time of 7 years post treatment for cancer. The quality of life domains included were sexual function, urinary irritation/obstruction, urinary incontinence, bowel, and hormonal health.
The results showed that adherence to an overall and healthy plant-based diet was associated with better sexual function/erectile function, less urinary irritation/obstruction and urinary incontinence, better bowel function and higher scores in the hormonal health domain.
The authors discuss how their results are in keeping with the results of prior studies. The positive effects of a plant-based diets are likely due to the higher fibre intake and the impact of numerous anti-inflammatory and antioxidant compounds in plants, along with the absence of harmful nutrients found in animal-sourced food. The authors mention that none of the participants were following a full plant-based or vegan diet and therefore there could be additional benefit for those consuming a whole food plant-based diet. Unusually, the authors dedicate a whole paragraph to reminding us of the benefits of eating a plant-based diet for planetary health and implying that since there are no downsides to this way of eating, this should be the default eating pattern.
The authors conclude ‘individuals with prostate cancer should be advised that incorporating a greater amount of plant-based foods into their diet could not only reduce the risk of comorbid conditions but also contribute to improved functional outcomes.’
What is the role of extra virgin olive oil in an otherwise healthy plant-based 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 results 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 and also may have been the reason for the positive impact on blood lipids.
- 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 been encouraged to eat more protein-rich plant-based foods.
- Although 21 of the 40 participants were already on lipid lowering drugs, there were 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.
Soya milk is a better choice for health than cow’s milk: An important question in nutrition science is always ‘instead of what?’ When considering a change in diet, one needs to consider what is being removed and what has replaced that food in the diet. Cow’s milk has always been considered a healthy addition to the diet of children and adults, mainly because it is better for health than other commonly consumed drinks such as fruit juice and sugar-sweetened beverages. But I always tell my patients that they can make an even better choices i.e. swapping cow’s milk for a soya drink. I felt I already had sufficient evidence to recommend this swap given the extensive scientific evidence supporting the consumption of soya and its beneficial impact on health. But more data is always useful!
This systematic review and meta analysis of 17 randomised controlled trials that compared cow’s milk to soya milk consumption and the impact on cardiometabolic health. The analysis showed that soya milk improves cardiovascular risk factors, including LDL-cholesterol, blood pressure and C-reactive protein, a marker of inflammation. Interestingly, there was no difference in results when considering soya milk with and without added sugar. The authors conclude ‘our findings support the use of fortified soya milk with up to 7 g added sugars per 250 mL as a suitable replacement for cow’s milk and suggest that its classification as ultra-processed and/or not healthy based on small amounts of added sugars may be misleading and need to be reconsidered to facilitate the recommended transition to plant-based diets.’
Another useful meta-analysis reminds us that soya does not have an oestrogenic effect and so we can be reassured there is no risk of harm from hormonal impacts.
I can not think of a single reason why humans need to consume milk from a cow. It’s not required for health, its production is harming the planet and of course it is terrible for the cows. You can read my article on dairy here.
Not all ultra-processed foods (UPFs) are bad for health: The dialogue around the health impacts of UPFs continues, with many suggesting we should shun all UPFs given their negative impact on health. However, not all UPFs are created equal and the commonly used NOVA classification only considers the degree of food processing without considering the nutrition or health impacts. A steak, classified as being an unprocessed food, is then wrongly considered as healthy whereas a plant-based meat alternative made of soya or seitan would be considered ultra-processed and regarded as less healthy, despite the evidence suggesting otherwise.
So it’s good to have more studies that assess the impact of subgroups of UPFs rather than putting them all together as if they were a homogenous group. This paper including more than 200,000 participants from the Nurses’ Health Studies and the Health Professionals Follow Up Study. It found that higher intake of UPFs was associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), but not stroke. A further analysis of pooled data from 19 cohort studies was also conducted. This found that total UPF consumption was associated with a significant increase in CVD, CHD and stroke. However, these associations were largely driven by consumption of processed meat, sugar-sweetened beverages and artificially-sweetened beverages. Ultra-processed savoury snacks, cold cereals, and yoghurt/dairy-based desserts were inversely associated with CVD and CHD risk. Ultra-processed bread and cold cereals were associated with lower stroke risk. When removing processed meat and sugar-sweetened beverages from total UPFs, the negative impact on cardiovascular health disappeared.
This is not the first study to show such results. A meta-analysis assessing the impact of UPFs on all-cause and cause-specific mortality found an association between higher consumption of UPFs and increased risk of all-cause mortality but this association was mostly driven by consumption of meat/poultry/seafood based ready-to-eat products. Analysis from the EPIC (European Prospective Investigation into Cancer and Nutrition) study showed that higher consumption of UPFs was associated with co-occurrence of multiple comorbidities relating to cancer and cardiometabolic health, but again this association was with the consumption of animal-based products and artificially and sugar-sweetened beverages. Other subgroups such as ultra-processed breads and cereals or plant-based meat and dairy alternatives did not show an adverse impact on health. Similarly and hot of the press, another analysis from the EPIC cohort study has shown that consumption of UPFs are associated with an increased risk of type 2 diabetes. However, UFP subgroups had differing effects. Savoury snacks, animal-based products, ready-to-eat/heat mixed dishes and artificially- and sugar-sweetened beverages were associated with higher incidence of type 2 diabetes, whereas breads, biscuits and breakfast cereals, sweets and desserts, and plant-based alternatives were associated with lower incidence.
So you get the point. Not all UPFs are created equal and they should not be considered a homogenous group since different subgroups or categories of UPFs having differing effects on health outcomes. Most of the negative health outcomes are driven by processed meat, sugar sweetened beverages and cakes/pastries/biscuits/crisps.
When plant-based milks and meat alternatives have been investigated as separate groups of UPFs, there does not appear to be a negative impact on health outcomes and in fact, according to a new review paper, plant-based meat alternatives may have considerable benefits for cardiovascular health compared to meat. Even within the category of plant-based meat alternatives there is a great variation between products, but the evidence suggests that if carefully selected, some plant-based meat alternatives have the potential to be healthier and nutrient-rich alternatives to animal-source foods and of course have the additional benefit of a smaller environmental footprint.
We have had some excellent reports this year on the topic of meat and dairy alternatives from the Food Foundation and Proveg demonstrating their benefits for human and planetary health.
Low-carb diets and plasma lipids. Despite the evidence supporting plant-based diets there seems to be continued promotion of a low-carbohydrate dietary approach for prevention and management of type 2 diabetes. Yet more and more evidence is accumulating that when low-carb diets emphasise animal sources of protein and fat, this is detrimental to long term health with increased risks of cardiovascular disease, certain cancers and premature death. This is just one of many studies to highlight the dangers of an animal-based low-carb diet. Researchers examined data from the UK Biobank. A low-carb high fat (LCHF) diet was defined as one consisting of no more than 25% of total daily energy or calories from carbohydrates and more than 45% of total daily calories from fat. The primary endpoint was the impact of LCHF diet on serum lipid levels; and the secondary endpoint was to investigate the association between LCHF dietary patterns and incident major adverse cardiovascular events.
A total of 70,684 participants completed a one-time self-reported 24-hour diet questionnaire and had blood drawn to check their lipid panels. Of these participants, 305 were identified as consuming an LCHF diet, mean age 53 and mostly women (73.3%). They were matched by age and sex with 1,220 individuals who reported consuming a standard diet. The results showed that, compared with those consuming a standard diet, individuals consuming an LCHF diet had significantly higher levels of LDL-cholesterol and apolipoprotein B. Furthermore, after an average follow-up of 11.8 years, those on a LCHF diet had a more than two-fold higher risk of experiencing incident major adverse cardiac events (MACE; defined as the composite of angina, myocardial infarction, coronary artery disease, ischaemic stroke, peripheral arterial disease, or coronary/carotid revascularisation), even after adjusting for other risk factors.
Of course this type of observational study has limitations and cannot establish causality between LCHF diet and an increased risk of major cardiac events. Additionally, the participants provided dietary information at only one time point, which may limit the interpretation of the study findings. Nevertheless, given that low-carb diets remain popular, the results should act as a note of caution. If low-carb diets are preferred, they should focus on replacing carbohydrates with plant sources of fat and protein.
Similar to protein, we know that plant sources of fat are healthier than fats from animal sourced foods. This is because saturated fat, predominantly found in animal source foods, has a direct effect of blood cholesterol level by down-regulating LDL-receptors in the liver. The more saturated fat consumed, the higher the LDL-cholesterol level, the key cause of atherosclerosis. In addition, saturated fat is associated with higher rates of type 2 diabetes, dementia and adversely impacts the health of the gut microbiome.
This study once again demonstrates the health benefits of consuming fats from plant sources. The paper analyses data from the National Institutes of Health–AARP Diet and Health Study, which included 407,531 men and women with a mean age of 61.4 years. Median daily dietary fat intake from plant and animal sources was 24.7 g and 29.3 g, respectively. After 24 years of follow, the results showed that participants consuming higher amounts of plant sources of fat had significantly lower rates of cardiovascular and all-cause mortality. Fats from grains and vegetables oils were found to be particularly beneficial. In contrast, greater intake of fat from total animal fat, dairy, and egg sources was associated with increased risks of overall mortality and CVD mortality. These associations remained significant even after adjusting for other known risk factors for mortality. Replacing 5% energy from total animal fat, red meat fat, dairy fat, or egg fat with an equivalent amount of total plant fat, fat from grains, or vegetable oils was associated with a 4% to 24% lower risk for overall mortality and a 5% to 30% lower risk for CVD mortality. Of note, fish fat was not associated with adverse health outcomes and replacing fish with plant sources of fat did not affect outcomes. Similarly, replacing white meat with plant sources of fat did not alter health outcomes.
Plant-based diets have environmental benefits: Although we don’t need more persuasion on the benefits of moving away from animal foods to a plant-based diet for planetary health, this paper from Sweden is a useful addition. It models the environmental, nutritional and economic benefits of replacing animal foods with plant-based alternatives (PBAs; meat, dairy and seafood) or whole plant foods and compares this to the typical Swedish diet. The researchers modelled six dietary scenarios; vegan, vegetarian and flexitarian for both PBAs and whole foods.
All six dietary scenarios led to improved nutritional profile compared to the current Swedish diet, with improvements in fibre intake, iron, folate, unsaturated fats, magnesium and lowering of saturated fat intakes. The short fall nutrients were vitamin D and B12 and selenium (a concern for all diet scenarios including the current Swedish diet). Salt intake increased in the PBA scenario but decreased in the whole food scenario. The PBA and whole food vegan scenarios had the greatest benefit for environmental health, including 52–56% reduction in greenhouse gas emissions and 32–44% reduction in land use. There were smaller benefits for reducing water use although a whole food vegan diet was estimated to use similar amounts of water to the current Swedish diet due to increased consumption of fruit and vegetables. The PBA scenarios increased food costs by a small amount (3–5%), whereas a whole food approach had the greatest potential to reduce food costs, with the whole food vegetarian scenario reducing costs the most, by 17%.
Overall, the researchers conclude that there are significant environmental benefits from replacing animal foods in the diet with plant-based foods without compromising nutritional quality. ‘Our findings highlight that minimising animal-sourced food consumption has a larger influence on reducing the environmental impact than choosing between PBAs or whole foods as replacements. This suggests that the different, more plant-based dietary scenarios that we assessed should be viewed as complementary, targeting different groups that strive to reduce the intake of animal foods. Including PBAs in dietary guidelines, as already prevalent in some countries, can promote the uptake of more sustainable diets based on consumer preferences by presenting a wider choice of plant-based products to select from’.
The prevailing narrative around regenerative farming continues to suggest that grazing animals are necessary and support increased carbon sequestration in pasture lands. However, there are now clear data to the contrary. A study published in Nature Communications concludes that it is not feasible for the global livestock industry to sequester enough carbon to cancel out its planet-warming emissions. The study finding are summarised in this excellent article.
When it comes to dietary patterns that support human health but also keep the food system within planetary boundaries we look to the Eat-Lancet commission report of 2019. Known as the Planetary Health Diet (PHD), it is composed of at least 85% whole plant foods, whilst minimising animal-sourced and ultra-processed foods. Most animal foods are not considered essential within this dietary pattern. A number of studies in 2024 have assessed the health and environmental aspects of adhering to the PHD. This study showed, in a large observational data set, that people who adhere the closest to this way of eating have significantly improved health outcomes and lower environmental impacts. The results showed that this type of diet pattern centred around fruits, vegetables, whole grains, beans, nuts and seeds reduced the risk of premature death by 30% with significant advantages for our major killers – heart and lung diseases and cancer. In addition, there were significant environmental benefits, including 29% lower greenhouse gas emissions, 21% lower fertiliser needs, and 51% lower cropland use.
Similarly, analyses using data from participants included in the UK Biobank study have shown that the PHD could have significant benefits for cardiovascular health, regardless of a persons underlying genetic risk. There may also be significant benefits for reducing the risk of depression and anxiety. 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.
Hot off the press at the end of 2024 we have a multi-criteria assessment of 24 meat and milk alternatives that integrates nutritional, health, environmental, and cost analyses with a focus on high-income countries. The paper concludes ‘unprocessed plant-based foods such as soybeans, peas, and beans are best suited for replacing meat and dairy in high-income countries, and performed well on all dimensions. In comparison, processed plant-based foods such as veggie burgers and plant milks were associated with less climate benefits and greater costs than unprocessed foods, but still offered substantial environmental, health, and nutritional benefits compared to animal-source foods… suitable alternatives to meat and milk exist and are available and affordable without necessarily requiring new technologies or product development’. We don’t need protein from insects or Bovaer added to cow’s feed. We have the solutions to our health and environmental crises in the form of plant-based foods.
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