A review of the week’s plant-based nutrition news 16th February 2020
The highlight of the week has got to be the review of Milk and Health in the New England Journal of Medicine. So unusual to see such an extensive review on one food type in a high impact medical journal.
MILK AND HEALTH: There are so many myths surrounding non-human milk consumption mostly propagated by the dairy industry. This article summaries the scientific data on dairy consumption. Here is a summary of the paper from one of the co-authors. Below are listed the main conclusions of the review.
1) Normal growth and development can be obtained throughout childhood without dairy products.
2) Overall evidence does not support a benefit of higher dairy consumption for prevention of fractures. Milk consumption in adolescence does not prevent fractures in later life and may even contribute to high incidence of fractures in countries with the greatest milk consumption. The image below shows that as total energy from milk intake increases, so does the risk of hip fracture.
3) Studies do not support the theory that milk consumption in children or adults helps maintain a healthy weight.
4) Milk consumption is not associated with better heart health. The effect depends on what dairy is compared to. Dairy consumption is better for heart health than red meat but less beneficial than fish and nut consumption. Impact on mortality is also based on what dairy consumption is compared to. As seen in the image below, plant protein consumption is superior to dairy when it comes to reducing mortality.
5) Dairy consumption does not lower the risk of type 2 diabetes.
6) Milk consumption is associated with a higher risk of prostate cancer, especially aggressive and more fatal forms. Also increased risk of endometrial cancer in women. BUT lower risk of colorectal cancer due to the calcium content.
7) Lactose intolerance is common worldwide. Cow’s milk consumption may predispose to allergies, asthma and eczema and may precipitate asthma exacerbations in adults.
8) No evidence to suggest organic dairy consumption negates the health concerns related to non-organic milk consumption.
9) Industrial dairy production is a major contributor to greenhouse gas emission, climate change, water use and pollution and antibiotic resistance.
10) In Western high income countries, all nutrients found in milk can be obtained from plant sources or supplements, in the case of vitamin D. There is no requirement for humans to consume dairy for health, which may in fact have negative consequences for health. In low income countries, if the diet is of low quality, dairy can be a source of nutrients.
Check out all the amazing options for plant-based mylks that are now available. Here is a great review of plant-based mylks from ProVeg International.
CHOOSE PLANT PROTEIN INSTEAD OF ANIMAL PROTEIN FOR HEART HEALTH: This paper can be summarised as the following ‘plant protein is better for heart health when compared to animal protein in part due to its lower sulfur amino acid content’.
Nothing we don’t know already but it’s always good to know the reason why. Animal protein is rich in sulphur containing amino acids — methionine and cysteine. We have known for a while that restriction of these amino acids in the diet may benefit health but the impact on long-term health has not been extensively investigated. This paper is the first epidemiological study to examine the impact of sulphur amino acid intake and cardiometabolic disease risk in adult humans. The study included >11,000 participants of the Third National Examination and Nutritional Health Survey study (1988–1994). Cardiometabolic risk was determined by a combination of factors, including blood pressure, kidney function blood levels of total cholesterol, HDL-cholesterol, triglycerides, insulin, glucose, glycated haemoglobin, CRP, uric acid and blood urea nitrogen. The results showed that most people were consuming far more than the estimated average requirement of sulphur amino acids. Higher intakes were associated with a significant increase in composite cardiometabolic disease risk scores.
THE CONCLUSION: switching to plant-derived protein may benefit heart health and thus has important public health implications.
Data are accumulating for benefits of restricting methionine in particular, in the diet. A recent paper highlighted the potential for cancer treatment. Methionine restriction altered cancer cell metabolism in favour of causing cancer cell death. The authors of the paper conclude ‘methionine restriction at levels that are tolerated in humans, and provide reasonable dietary possibilities — including levels of methionine that may be possible to obtain with vegan or some Mediterranean diets’. A list of foods and their methionine content can be found here from brendadavidrd.com.
VITAMIN B12 LEVELS AND RISK OF DEATH: This paper on the surface may seem rather alarming for those following a plant-based diet. It suggests that those with the highest blood levels of B12 have a higher risk of death from any cause.
Higher B12 levels can be a reflection of underlying illness such as kidney and liver disease and although this was adjusted for in the analysis it may still remain a source of confounding. A major limitation of the study is that dietary information was not included. We known that those eating the most meat are likely to have higher B12 levels and meat consumption per se is associated with a higher risk of death. Nonetheless, it is not the first study to suggest higher levels of B12 in the blood may have adverse health effects. In general, supranutritional levels of vitamins and minerals taken in supplement form have been associated with negative health effects. This includes vitamin E supplementation and an increased risk of lung and prostate cancer and selenium supplementation with possible increased risk of type 2 diabetes and no benefit for cancer risk reduction.
I continue to recommend B12 supplementation for those on a vegan/plant-based diet but this should be at nutritional doses and not high doses. The UK vegan society recommendations are pretty sound. It may be prudent to have a blood test every 3 years to make sure your blood levels of B12 remain within the recommended ‘normal range’ — not too high and not too low. Like with most things in life and medicine, more is not always better.
MORE DIETITIANS IN PRIMARY CARE FOR THE UK: The need for dietitians in primary care has been recognised in the new GP contract. Given that unhealthy diets are one of the top causes of death and disability in the UK, this is a really positive step forward. The BDA have in recent years shown increasing support for healthy plant-based diets, including a memorandum of understanding with the UK vegan society, a statement supporting plant-based diets as healthy for all stages of human life and their One Blue Dot campaign that recommends plant-based diets for environmental sustainability.
PLANT PROTEIN PRODUCTION MORE SUSTAINABLE THAN ANY SOURCE OF ANIMAL PROTEIN: A nice article reminding us that all plant sources of protein are more environmentally sustainable that animal sources of protein, regardless of the production methods. ‘As consumers, the biggest difference we can make is to eat more plant-based sources of protein such as tofu, nuts, peas, and beans. This is the case regardless of where you are in the world’.
Choosing plant protein over meat and dairy protein is not only a win for the environment but has been associated with reduced chance of death from any cause and reduced risk of cancer, kidney failure, heart failure and more. There are a multitude of reasons for the detrimental effects of animal-derived protein. These are summarised in this review, but include the high saturated fat content, the higher amounts of sulphur amino acids and branched chain amino acids, the production of TMAO from carnitine and choline, the generation of advanced glycation end products on high temperature cooking, the inflammatory effects of haem iron and the conversion of nitrites in processed meat to N-nitroso-compounds.
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