Review of the week’s plant-based nutrition news 21st February 2021

This week I cover our very own publication on psoriatic arthritis. In addition, the impact of a vegan diet on NAFLD, vitamin D and cancer risk, impact of egg and cholesterol intake and more about diet and planetary health.

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HEALING FROM PSORIATIC ARTHRITIS: We are so thrilled to have published Kate Dunbar’s story of managing psoriatic athritis on a whole food plant-based diet (WFPBD). Kate is patient advocate at Plant-Based Health Professionals UK. She has now been off her medications for 3 years and enjoys regularly running 10km. It’s interesting that a vegan diet inclusive of processed foods, oil and added sugar was not sufficient to induce a remission. It was only after transitioning to a no oil, whole food plant-based diet that she was able to achieve a remission without medications.

We hope this case report provides some hope. At present, with conventional medical management, less than 2% of people achieve a sustained remission and are able to come off medication. We already know that anti-inflammatory diet patterns such as the Mediterranean diet can reduce the risk and progression of athritis, with studies mainly focussing on rheumatoid arthritis. There are little data currently on impact of diet and lifestyle on psoriatic arthritis and most lifestyle interventions focus on maintaining a health weight, avoiding smoking and regular physical activity.

An exclusively plant-based diet is an attractive option for patients with various forms of arthritis given its anti-inflammatory properties. This is a consequence of the vast quantities of antioxidant compounds and phytonutrients in plant foods and their ability to lower markers of inflammation such as CRP. A few intervention studies have been performed and show promise. A randomized study of a WFPBD in patients with osteoarthritis was able to show improvement in self-reported pain and function in the intervention group. A small study of a low-fat WFPBD in patients with rheumatoid arthritis resulted in a significant reduction in CRP and rheumatoid factor activity, while also improving symptoms. The other mechanisms that may explain the benefits seen are reduced exposure to dietary antigens, improvement in the health of gut microbiome, and elimination of inflammatory foods in the diet such as red and processed meats. A recent case report highlighted the benefit of fasting followed by the introduction of a low-fat vegan diet with improvement in symptoms and reduction in medication use.

The other important aspects of a whole food plant-based diet are that there are no harms associated with it and it can reduce the risk of cardiovascular disease and cancer, conditions for which patient with psoriasis are at increased risk for.

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VEGAN DIET FOR NON-ALCOHOLIC FATTY LIVER DIEASE (NAFLD): NAFLD is the accumulation of fat in the liver. When progressive, it can lead to liver fibrosis and cirrhosis. The incidence of NAFLD is rising, with up to 20% of the UK population having some evidence of NAFLD. The key drivers of NAFLD are obesity, dyslipidaemia, insulin resistance and metabolic syndrome. These factors are intimately related to diet and lifestyle. The specific components of diet that are associated with an increased risk of NAFLD include, saturated fat, red and processed meat, refined carbohydrates and fructose (from sugar and high fructose corn syrup). Can you believe that NAFLD was not even recognised as a clinical entity prior to 1980!

It’s great to see a study evaluating the role of a vegan diet given its ability to improve weight, lower insulin resistance and reduce visceral fat. Obviously a vegan diet can be healthy and composed of whole plant foods or less healthy when composed of processed vegan foods. This study included 29 patients with NAFLD who adopted a vegan diet for 6 months, although 4 patients subsequently dropped out leaving 26 patients for evaluation. The results showed a significant reduction in weight (median 5kg), BMI (median 1.66) and normalisation of liver function in 20 of 26 patients (76%). Four patients were also able to reduce medication dosage for their underlying cardio-metabolic diseases.

Clearly there are limitation to this study. There was no control group, only a small number of patients, we aren’t given details of their actual food intake, participants were only contacts by phone and adherence was not evaluated. Nonetheless, these preliminary data are encouraging and add a low risk option for patients with only positive side-effects.

The available evidence on dietary management of NAFLD, which also takes into account the importance of weight loss, has been recently summarised in an excellent review paper.

  1. Calorie restriction with a 500–1,000 kcal daily deficit is an extremely effective lifestyle intervention for both the prevention of NAFLD and histological improvement in patients with established disease. The goal of calorie reduction should be to achieve ≥10% overall body weight loss.
  2. Reduce intake of red and processed meats
  3. Reduce/eliminate refined carbohydrates and especially fructose
  4. Increased fibre intake through the consumption of fruits, vegetables, whole grains and legumes
  5. Replace dietary saturated fatty acids with mono-unsaturated and poly-unsaturated fatty acids
  6. Coffee consumption is protective against the development of NAFLD and disease progression. Moderate to heavy alcohol consumption should be avoided in the presence of obesity, NAFLD, and other metabolic risk factors. Abstinence is advised for patients with advanced fibrosis.

Diets that incorporate these recommendations include plant-based diets such as the DASH, Mediterranean, vegetarian, and vegan diets.

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VITAMIN D SUPPLEMENTATION AND CANCER: The general advice for cancer prevention and treatment is to avoid supra-nutritional doses of dietary supplements and obtain nutrients predominantly from diet. However, vitamin D supplementation is an outlier to this advice. We know that vitamin D acts more as a hormone than a vitamin and many of us have lower than optimal levels due to limited exposure to the sun. Food sources are often inadequate for raising vitamin D levels to the normal range and vitamin D supplementation is relevant to all of us when we can not get enough sun exposure.

With regards cancer, the data has been mixed. As it stand now, there is insufficient evidence supporting vitamin D supplementation for cancer prevention but a recent meta-analysis suggests that supplementation to achieve blood levels between 50–130nmol/l may benefit cancer survival. On the basis of the results of this meta-analysis, the current study from Germany modelled the costs and savings for preventing cancer deaths by vitamin D supplementation in the population for those aged 50 years. The number of preventable cancer deaths was estimated by multiplying cancer deaths above age 50, based on 2016 data, with the estimated reduction of cancer mortality from vitamin D supplementation according to the 13% reduction shown in the meta-analysis. Cost saving were estimated by multiplying this number by estimated end-of-life cancer care costs (€40,000). Annual costs of vitamin D supplementation at a dose of 1000iu/day were estimated at 25€ per person. Vitamin D supplementation was estimated to prevent almost 30,000 cancer deaths per year at a cost of approximately €900 million and savings of €1.154 billion, suggesting net savings of €254 million. The authors conclude that the results support promotion of supplementation of vitamin D among older adults as a cost saving approach to substantially reduce cancer mortality.

Although we would prefer more robust clinical data to support such an intervention, as a cancer doctor I do make sure my patients have an adequate blood vitamin D level. Virtually all my patients have a suboptimal level when they come to see me. As a minimum, based on the data, all patients with cancer should be aiming to achieve a blood vitamin D level within the normal range and probably around 75nmol/l, which usually requires a daily dose of 1500–2000iu per day.

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EGGS, CHOLESTEROL AND RISK OF DEATH: The role of eggs in the diet remains hotly debated. One thing is for sure, eggs are not necessary in the diet. Their use has just become a norm in our modern society. Whether their consumption is harmful or not can be difficult to tease out. This latest paper on the topic of egg and cholesterol consumption includes data from 521,120 participants (aged 50–71 years, mean age = 62.2 years) included in the NIH-AARP study, a large prospective cohort initiated October 1995–May 1996 and followed for a median of 16 years. The overall median intakes of whole eggs and cholesterol were 8 g/2,000 kcal/day and 208 mg/2,000 kcal/day, respectively. The study examined the impact of egg and cholesterol intake on all-cause mortality (death from any cause), cardiovascular disease (CVD) and cancer mortality. The study is useful as is distinguishes between whole egg consumption and egg white only.

Egg consumption was associated with a less healthy diet overall, lower socioeconomic status and other unhealthy lifestyle habits. Whole egg consumption was strongly associated with higher all-cause mortality but this finding was no longer significant after adjsuting for cholesterol intake. In contrast, egg white alone was significantly associated with lower all-cause mortality. Each additional 300 mg of dietary cholesterol/day was associated with a 19% higher risk of all-cause mortality. Each additional half egg/day was associated with a 7% higher risk of all-cause mortality. Intakes of whole eggs and cholesterol were both positively associated with CVD mortality, whereas this was not the case for egg whites. With regard to cancer mortality, there was a positive association for the intake of whole eggs and cholesterol and an inverse association for consumption of egg white. Each additional half a whole egg/day was associated with a 7% higher risk of CVD mortality and cancer mortality. Each additional 300 mg of dietary cholesterol/day was associated with a 16% and 24% higher risk of CVD and cancer mortality, respectively. Whole egg and cholesterol intakes were associated with higher mortality from respiratory disease (RD) and diabetes, but with lower mortality from Alzheimer disease. Egg white consumers had lower RD, Alzheimer disease and chronic liver disease mortality compared with non-consumers. Substitution analysis showed that there were benefits in reducing mortality from replace eggs with egg whites, poultry, fish, dairy products, nuts, and legumes. The greatest effect was seen for substituion of eggs for nuts and legumes.

Overall, these data show that egg consumption, predominantly due to the cholesterol content, is associated with a higher risk of dying from a number of chronic conditions. These data are concordant with a recent study that included data from 6 prospective cohort studies in which each additional half an egg/day was associated with 6%, 8%, and 8% higher risk of incident CVD, CVD mortality, and all-cause mortality, respectively.

The question then arises as to whether egg white consumption alone should be promoted? My answer is why? There are better choices to make for health, the environment and for the animals. Health benefits from whole plant foods far outweigh the benefit of consuming egg whites. With a global effort to cut food waste, producing a ‘food’ to then throw away half seems nonsensical.

The authors conclude ‘Our findings support limiting cholesterol intake and suggest replacing whole eggs with egg whites/substitutes or other alternative protein sources for facilitating long-term survival and health’.

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THE PUBLIC HEALTH IMPLICATIONS OF THE PARIS AGREEMENT: The 2015 Paris Agreement is an international agreement to keep global warming below 2°C by adopting carbon reducing policies. Yet little seems to have been achieved over the last 5 years since the signing, with most countries doing little better than continuing with ‘business as usual’ policies in the relevant sectors. This study evaluated the potential impact of emissions generated from energy, agriculture and transport sectors based on 3 different emissions scenarios on health outcomes, specifically deaths attributed to air pollution, diet-related risk factors and physical inactivity. They modelled the impact on nine nations, including the UK, that are home to around 50% of the worlds population and responsible for 70% of global emissions.

Focussing in on the diet-related scenarios, the study examined the impact of half the population adopting a flexitarian diet and half adopting a vegan diet inline with Eat-Lancet commission planetary health plate. The flexitarian dietary patterns contain no processed meat, low amounts of red meat (including beef, lamb, pork) and sugar, moderate amounts of poultry, dairy and fish, and generous amounts of fruits, vegetables, legumes, and nuts. In the vegan dietary pattern, all animal source foods were replaced to one third by fruits and vegetables and to two thirds by legumes. The study calculated that just this dietary approach alone could save 6, 435 910 deaths in 2040 from coronary heart disease, stroke, type 2 diabetes, cancer and respiratory disease. In the UK alone this equates to 141 deaths per 100,000 population avoided.

So once again reducing red/processed meat and increasing whole plant foods in the diet significantly improves global health by increasing diet quality, thus reducing the risk of chronic illness, and reducing the impact of the food system on climate change. Time summarises the findings here.

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