A review of the week’s plant-based nutrition news 14th November 2021
This week I cover new dietary guidance from the American Heart Association, medication use in vegans, a vegan intervention in healthcare works, an update on nutritional controversies and the increased risk of frailty with red meat consumption.
DIETARY GUIDELINES FOR CARDIOVASCULAR HEALTH: These guidelines provide a useful update on the current best available evidence on diet and cardiovascular health. There is an emphasis placed on dietary patterns rather than individual foods or nutrients and the report highlights the essential role of healthy nutrition from early life.
The key elements of a heart healthy diet pattern include the ability to maintain a healthy weight and that it is centred around fruits, vegetables and whole grains. Protein should be obtained mostly from plants (legumes, including soya, and nuts) and processed foods, sugar-sweetened beverages, tropical oils and animal fats should be minimised, whilst also limiting the use of added salt and avoiding alcohol. Fish, seafood and low fat dairy is still considered compatible with a heart healthy diet but the guidelines infer that meat and poultry are not necessary in the diet and ‘if desired’ should be lean cuts with processed meats best avoided. There is a cautionary note for plant-based meat alternatives, which are often highly processed.
An emphasis is placed on replacing saturated fat and trans fat (including that found in meat and dairy) with unsaturated sources of fat (from whole plant foods such as nuts and seeds and also non-tropical vegetable oils). I am pleased that the report is clear that alcohol should not be consumed and intake should be limited or avoided.
This type of heart healthy diet pattern is also noted to be beneficial for the prevention of type 2 diabetes, renal failure and cognitive decline. In addition, there is emphasis placed on the environmental impact of our diet choices, noting that healthy vegetarian diets are not only heart healthy but consistently associated with a lower environmental footprint. The guideline pays attention to the societal and cultural challenges that prevent people from adopting healthy diet patterns, including socioeconomic factors, food insecurity, structural racism and food industry marketing of unhealthy foods. The report notes that public health interventions are required so that healthy food is affordable and accessible too all.
Overall, a very good guideline which certainly features plant foods at its core and it entirely compatible with consuming a healthy whole food plant-based diet.
ASSOCIATION OF DIET WITH USE OF MEDICATION: This paper comes at a time when the UK government has published an independent review on overprescribing ‘A plan to reduce overprescribing to make patient care better and safer, support the NHS, and reduce carbon emissions’. It notes that overprescribing is a serious problem that can lead to hospital admissions and preventable harm and even death, with people from ethnic minority backgrounds being affected the most. A fifth of hospital admissions among adults over 65 years are the result of adverse effects of prescribed medications and 25% of the NHS’s carbon footprint comes from medicines.
The current study examined the association of medication use with diet pattern in 328 participants aged 60 years or older from the Adventist Health Study in Loma Linda. Questionnaires were used to collect data on diet, lifestyle, chronic conditions, biometrics and diet. 57% of participants were non-vegetarian (n=187), 21.6% lacto-ovo vegetarian (n=77), 10.6% pesco-vegetarian (n=35) and 10.6% vegan (n=35). Increasing age, body mass index (BMI) and underlying chronic conditions were associated with increased use of medication. After controlling for exercise, education, and the presence of chronic conditions, the results suggest that a vegan diet is associated with a 58% reduction in the use of medications when compared to a non-vegetarian diet (1.5 pills versus 3.8). Age and BMI still remained significant factors. There was no apparent benefit for a lacto-ovo vegetarian diet.
I am always delighted to see such positive results of a vegan diet, but have to admit this is not the most robust study. The study design is cross-sectional meaning just one point in time was assessed and therefore one can not assess cause and effect. In addition, other factors affecting medication use such as cultural, ethical, religious, were not taken into account. Ethical vegans may be less likely to use medications due to issues around animal testing. Nonetheless, we do know that within the Adventist Health Studies, vegans have better cardiometabolic health, less heart disease, cancer and type 2 diabetes and thus less reason to be reliant on prescribed medications.
HEALTHCARE WORKS AND A VEGAN DIET INTERVENTION: At the start of the pandemic, we, and others were critical of companies delivering free ‘junk food’ to NHS workers in the UK. Sadly, healthcare workers are just as likely to to be overweight and have underlying health conditions as the general public and therefore healthy diet and lifestyles are so important, despite the challenges within a busy healthcare setting.
The Physicians Committee conducted a randomised study of a vegan diet in overweight healthcare workers. As much as I would like this to be a game-changing study, it really did not end up being very robust, despite the good intentions. Although 237 people attended the initial information session for the study, only 16 were entered into the control group and 16 into the vegan intervention group. However, 20 then withdrew due to pandemic related factors. This left a study of 12 people who were then all placed on a vegan diet after a run in phase where they acted as their own control. But by the end only 4 remained in the original intervention group and 5 in the control group. So tiny numbers with a massive rate of dropout.
Despite these major shortcomings, the results showed that a 12 week vegan intervention led to significant reductions in total and saturated fat consumption whilst increasing carbohydrate consumption. There was a significant decrease in body weight (5.6kg) BMI, fasting glucose (11.4 mg/dl) total and LDL-cholesterol (30.7 and 24.6 mg/dL respectively) and diastolic blood pressure (by 8.5mmHg). The overall satisfaction with the diet was positive.
The main takeaways are that a plant-based or vegan diet is very effective at improving cardiometabolic risk factors and this can occur in a short period of time. Despite the small number of participants the results were still statistically significant when comparing the participants usual diet in the control phase and thus demonstrates the magnitude of change that is possible. However, the study also exemplifies the challenge of sustainable behaviour change in a high stress, busy profession.
NUTRITION CONTROVERSIES: A useful paper written by a number of plant-based physicians from the USA. It states the aim is ‘to help clarify some of the confusion so that health care professionals are better able to inform their patients and the public about optimal health choices’. It is a follow-up on the previous papers from 2017 and 2018, which are well worth reading. Below are the headline messages from the current update
Artificial and non-nutritive sweeteners: There are mixed data on whether these sweeteners are better for health than added sugar. Overall they have been shown to increase the risk of type 2 diabetes, obesity, hypertension, and all-cause mortality. Therefore, the authors conclude ‘Whether artificial sweeteners can be safely used as a replacement is not yet clear. However, given the current evidence, it is likely that they should not’.
Cocoa/Cacao: Some good news here, regular consumption of cacao has been associated with health benefits, especially for cardiometabolic health. However, these benefits will be negated if cacao is consumed in the context of high sugar and dairy content. My recommendation (not the authors), stick to dairy-free products with at least 70% cacao and the higher the better.
Soya: This controversy is an easy one to assess. There are an abundance of data demonstrating that the consumption of minimally processed soya foods and soya milk is associated with health benefits and this review finds that the strongest evidence is for reducing the risk of death from CVD and cancer.
Plant-Based Meat Alternatives (PBMAs): Expected caution here with the newer, more processed PBMAs, which tend to be high in salt and saturated fat (usually from coconut or palm oil). Although small studies to date suggest they may be better than eating meat, they can not be considered healthy as such and authors conclude ‘Until more data are available, minimally processed plant-based proteins, such as traditional soya, pulses, and nuts should be promoted to patients as meat substitutes’.
Dietary nitrates: Nitrates from plant foods such as leafy greens and beetroot have been consistently associated with benefits for blood pressure, endothelial function and better athletic performance. These foods should be encourages. However, nitrates and nitrites found in processed meat are not considered healthy as they combine under acidic conditions with certain compounds concentrated in meat, including amines and alkyl amides, to form potentially carcinogenic N-nitroso compounds. This reaction is inhibited by intake of vitamin C and other antioxidants concentrated in many plant-sourced foods.
Grass-fed versus grain-fed meat: Many still consider flesh from grass-fed animals as a healthy choice. Of course, these animals are not fed grass for their entire lives but at least part of it. This does seem to alter the nutritional profile of the meat with less saturated fat and higher levels of polyunsaturated fatty acids and certain antioxidants. There have been two small short studies investigating the impact of grass-fed meat but they were unable to show any benefit for cardiovascular biomarkers such as cholesterol, triglycerides, insulin sensitivity or blood pressure. There are no long-term studies. So at present there are no data supporting the hypothesis that flesh from grass-fed animals is a healthy choice. The better option for health is to choose protein from plant sources as per the national and international consensus.
RED MEAT AND FRAILTY: In general, it is recommended that older adults increase protein consumption, especially if they are frail or at risk of sarcopenia. The European guidelines recommend 1–1.2g/kg for adults >65 years of age. This is often assumed to be best obtained form animal foods, but a number of studies now support the consumption of plant protein instead of animal protein for healthy ageing
This new study reiterates the negative impact of red meat consumption in particular on the risk of frailty. The study included 85871 women from the Nurses’ Health Study who were greater than 60 years of age. Frailty was defined as having at least three of the following five criteria from the validated FRAIL scale: fatigue, low strength, reduced aerobic capacity, having ≥5 chronic illnesses, and unintentional weight loss ≥5%. The occurrence of frailty was assessed every four years from 1992 to 2014 and this was correlated with the consumption of unprocessed and processed red meat
During the median 14 years of follow up, there were 13,279 cases of frailty identified. Higher intake of red and processed meat was associated with an increased risk of frailty. Each one serving increase in total red meat, unprocessed red meat and processed red meat intake was associated with a 13%, 8% and 36% increase in risk of frailty, respectively. When individual components of frailty were assessed, a one serving increase in intake of total red meat, unprocessed and/or processed red meat intake was associated with a 5–9% increase in risk of fatigue, 8–19% increase in risk of low strength, 8–22% increase in risk of reduced aerobic capacity, 12–20% increase in risk of 5+ chronic illnesses, but no association was observed for weight loss. The associations with red meat consumption were linear suggesting a more certain association. The findings were independent of physical activity levels.
Replacing one serving/day of unprocessed red meat with other protein sources was associated with significantly lower risk of frailty; the risk reduction estimates were 22% for fish and 14% for nuts, while for replacement of processed red meat, the percentages were 33% for fish, 26% for nuts, 13% for legumes, and 16% for low-fat dairy. Substituting red meat for poultry did not appear to be beneficial. Substituting processed red meat for unprocessed red meat was still associated with a higher risk of frailty.
The authors suggest that despite the purported benefits of higher levels of leucine in meat, required for muscle protein synthesis ‘the protein content of meat can be counterbalanced by large amounts of detrimental components, including saturated fatty acids with low amounts of linoleic acid, haem iron, sodium, and nitrites present in processed red meat’. In addition, the negative impact of red meat consumption on blood cholesterol and inflammation are likely to be contributing factors. The authors conclude ‘habitual consumption of any type of red meat was associated with a higher risk of frailty….These findings are in line with dietary guidelines promoting diets that emphasize plant-based sources of protein’.
Previous analysis from the Nurses’ Health Study reported dietary factors that predicted for an increased risk of frailty in older women. This study included 71,941 women aged ≥60 years. The same Frailty scale was used. Diet was classified based on adherence to 3 healthy diet quality scores. During more than 22 years of follow-up there were 11,564 cases of frailty. Adherence to all healthy diet patterns resulted in a significant reduction in the risk of frailty in the order of 18–25% with incremental benefits with greater adherence. The common factors that appeared to be beneficial in these diet patterns were lower consumption of red and processed meat, lower sodium intake, higher ratio of monounsaturated to saturated fat, vegetables, and possibly moderate alcohol intake.