A Case for Plant-based Diets

Ellen-YPAS-BallBy Matt Betts

Who are you?
Good question. I wear a few different hats: mother of twins; Buddhist; poet… I’m also a low fat raw vegan and an ST6 trainee in Paediatrics and Child Health in Liverpool. I have a BSc in Biomedical Sciences and an MSc in Public Health, and last year I completed the eCornell certificate course in plant-based nutrition. I write a couple of blogs (www.kidseatplants.com and www.ellenstorm.com) and tweet @kidseatplants and @drellenstorm.

What gets you up in the morning?
My alarm clock, or my kids. Otherwise I’d still be there at lunchtime.

What does the term ‘selective’ mean to you, and how does it relate to your diet and lifestyle?
It doesn’t mean anything – I’ve never heard the term before. But I guess since we all have a fixed calorie quota for the day, we are all selective to some extent. We all have to decide what to put in our pot. The more of one thing we put in, the less of something else. It’s a bit like the economic concept of opportunity cost. Every time you eat a slice of bread, that’s a hundred-or-so calories-worth of broccoli lost, with all its vital phytonutrients and antioxidants. So the opportunity cost of eating the bread is the broccoli you didn’t eat. I suppose it’s just that some people make more conscious selections than others. Unconscious choices are based on availability and social norms, taste preferences, marketing and habit. Conscious choices are based on evidence (however flawed) and ethics.

Why do you recommend a plant-based diet?
Because plant-based diets are associated with greater longevity[i], and have also been shown to reverse atherosclerotic heart disease, the number one killer of a third of us in the Western world[ii-iii].

For example in the Adventist Health Study 2, for 73,308 participants over 5 years, the adjusted hazard ratios for all-cause mortality in comparison to non-vegetarians were 0.88 (95% CI, 0.80-0.97) for vegetarians (all types); 0.85 (95% CI, 0.73-1.01) for vegans; 0.91 (95% CI, 0.82-1.00) for lacto-ovo vegetarians; 0.81 (95% CI, 0.69-0.94) for pesco-vegetarians; and 0.92 (95% CI, 0.75-1.13) for semi-vegetarians. Significant associations with vegetarian diets were detected for cardiovascular mortality, non-cardiovascular non-cancer mortality, renal mortality, and endocrine mortality[iv].

By extension, why does that mean we shouldn’t eat animal-based products?
I hate the word should. Eat them if you like, but understand that you might die younger or be more likely to suffer from various chronic debilitating diseases than you otherwise would. They are at best unnecessary and at worst actively harmful to the human body. As for your conscience, that’s between you and your food.

But, what about the paleo diet?  And, what about our teeth?  We’ve EVOLVED to eat animals, right?
You try catching and killing a small animal with your bare hands and eating it raw using only your teeth and nails. Fancy it? Then try walking up to an apple tree, picking the juiciest apple and eating it using only your highly evolved body and senses. We see colour, and desire sweetness, because these faculties help us to source the ripest fruit in the forest. Hunting, cooking and tool use are relatively recent developments in an evolutionary sense. The first stone tools were used about 2.6 million years ago, heralding the Paleolithic period that lasted until about 10,000 years ago (when arable agriculture – grain consumption – and the domestication of animals – dairy consumption – began). The ability to procure and cook meat offered a survival advantage as human beings migrated further away from the equator. But survival to reproductive age, which is all nature is interested in, is not the same as survival into old age, and we pay a heavy price in terms of longevity for our over-reliance on animal products in more northerly latitudes. Our physical bodies evolved much earlier (the basic ape body plan evolved about 25 million years ago), and they are perfect for finding and consuming the naturally occurring plant foods that were abundant at that time. As for our teeth, they most closely resemble those of our closest living relatives, the chimpanzees and other great apes (although we do not have the long, pointed canines that chimpanzees and other carnivores do), all of whom consume mostly plants, with the majority of their calories coming from fruit[v]. Most of the chimpanzee’s diet in the wild consists of fruit (mainly figs) and green leaves. They do consume insects and some will occasionally eat meat, but these constitute a tiny proportion of their total calories. They get their vitamin B12 mainly from bacteria present in the soil and on the surface of their foods, and captive apes have been shown to develop B12 deficiency when fed fruits and vegetables that have been washed in chlorine, like the ones sold in supermarkets today. If you exclude all animal products from your diet, and don’t eat insects or soil, then it is necessary to take a B12 supplement.

There is one point on which the paleo and vegan camps agree however, and that is that consuming dairy products is a really bad idea. More than 65% of the world’s population does not consume dairy in any form after weaning[vi] and their bones are just fine, and we are the only species on the planet to consume the milk of another species. Yet somehow the entire population of the Western world seems to believe without question that milk is essential for healthy bones and teeth. This is nothing but testament to the power of years of marketing by the dairy industry. In fact, countries that consume the highest amounts of calcium (mostly from dairy) also have the highest rates of hip fracture[vii].

It is possible to plot a graph of hip fracture rates against national calcium consumption, and there is a positive correlation. How do we begin to understand this observation, first published in 1986 by Harvard Professor Mark Hegsted? It can take a long time for scientific knowledge to enter public consciousness (about 30 years in the case of the connection between smoking and lung cancer – a lot of people died in that time), particularly if there are strong economic motivations to keep it within the covers of peer-reviewed journals. Put another way, there are a lot of people with vested interests in our continuing to consume dairy. There is also a strong cultural bias: we like milk; it forms the basis of many of the foods we grew up on and associate with love and nurture; we have been consuming it for so long that we cannot imagine anything different.

But when we see something in science that doesn’t fit with what we currently believe to be true, we need to think again. Is the data correct? Is there a plausible mechanism?
The data does seem to be correct. One way of assessing this is to look at the problem from several different angles, to see if it all adds up. It is possible to plot hip fracture rates against the ratio of vegetable to animal protein in the diet in different countries. Those countries with the highest ratio (mostly plant foods, very little animal protein) have been shown to have almost no cases of hip fracture at all. In individual women too (over the age of 65), those consuming high amounts of animal protein compared to plant protein have been shown to have 3.7 times more fractures than, and to lose bone four times as fast as, those at the opposite end of the scale.

One proposed mechanism is that a high protein intake, particularly from animal sources, causes the blood to become more acidic. The healthy body maintains its pH within a very narrow range through a number of mechanisms, including buffering by calcium mobilised from the bones. This calcium is then excreted in the urine, and so is lost from the body. The bones become weakened, and high levels of calcium in the urine also cause the increased formation of kidney stones.

So according to this theory, it isn’t the calcium itself in dairy products that is causing the problem, so much as the protein it comes packaged with. And those populations who consume a lot of dairy produce tend to also consume a lot of meat, eggs and fish.

Whole plant foods do contain calcium, so dairy is not our only potential source. Good plant sources of calcium include vegetables (especially leafy greens), beans, figs, almonds, flax seeds, sesame seeds, oranges, tofu and fortified products[viii]. Those following a plant-based diet may consume less calcium in total, but they appear to absorb it more efficiently from the digestive tract. They also lose much less in their urine and use what they do take in to achieve better bone health overall. It is calcium balance, rather than absolute intake, that is important.

But where do you get your protein?
Seriously – this is really important…

Aside from the issue of the adverse effect of excessive protein consumption on bone health, in the 1960’s and 70’s a story began to emerge around the potential role of dietary protein in cancer promotion in particular[ix]. It was observed that children in the Philippines, who ate higher amounts of protein, generally those living in more affluent areas, had higher rates of liver cancer. At about the same time scientists in India published the results of an experiment in which rats that had been exposed to the potent carcinogen aflatoxin were fed diets containing either 5% or 20% casein (the main protein found in cow’s milk). All the animals fed the 20% casein diet went on to develop tumours, while none of those fed the 5% casein diet did. This marked effect has been confirmed in repeated studies in different laboratories around the world. It was later shown that switching rats from high to low casein diets could switch off tumour development, and vice versa. In another study animals fed the two diets were followed for the duration of their natural lifespan. At 100 weeks of age all the rats consuming the low protein diet were alive, while all those consuming the high protein diet were dead. A similar effect has also been shown in transgenic mice transfected with the hepatitis B virus, and in promoting mammary (breast) cancer in rats exposed to two other experimental carcinogens.

The percentage of dietary casein required to stimulate the growth of tumour cell clusters was found to be about 10%. Interestingly the recommended daily amount of dietary protein for human beings works out as between 8 and 10% of total calories. This is not an arbitrary figure but is derived from nitrogen balance studies carried out to determine exactly how much protein our bodies need. However most people consuming a standard western diet consume between 11% and 22% of their total calories from protein. Most of this protein is derived from animal sources, as we have been led to believe for many years in the West that meat and dairy products are necessary sources of complete protein for human beings. However it is interesting to observe that wheat and soy proteins did not produce the same cancer promoting effect in laboratory animals. Wheat and soy proteins are incomplete proteins, which means they do not by themselves contain all the essential amino acids required for human tissue growth and repair. However when the missing amino acids were artificially added to the animals’ feeds to make them complete, wheat and soy proteins acted in the same way as casein. This suggests that complete proteins, far from being the healthy proteins our bodies need, are actually harmful and cause cancer to develop where it might otherwise not have done, even in the presence of an underlying mutation.

Meanwhile it is easily possible to obtain 8-10% of our total calories from the proteins found in whole plant foods. All plant foods contain protein: 20% of the calories in broccoli are derived from protein, 31% in spinach, 18% in chickpeas, 23% in peas, 15% in wild rice. You get the idea. Most fruits come in at less than 10%, so if you eat a varied whole-food, plant-based diet you will naturally take in protein in the optimal range and what is more, it will be healthy, non-tumour promoting protein.

Well, you might ask how we can be so sure that studies carried out in rats and mice apply to humans. This would be a reasonable question. How can we find out if this situation also occurs in human beings? We could conduct rigorous dietary intervention studies with cancer patients, randomising them to either their normal diet or a low (<5% of total calories) protein diet and see how they get on. So far, nearly fifty years on from the original finding, to my knowledge and despite the millions of pounds spent annually on cancer research, this relatively simple experiment has not been done.

While we can debate the reasons for this and await further research, there are some other clues to help us in the mean time. Rates of cancer in populations traditionally consuming whole-food plant-based diets, such as breast cancer in traditional rural Chinese women for example, are much lower than they are in the West, while those migrating from these areas to more affluent cities or countries where meat and dairy consumption are prevalent see their risk of cancer rise significantly within two generations. This suggests a primarily environmental cause for most of the cancers prevalent in the West today. There are also many, many anecdotal stories of individuals improving their cancer outcomes by changing their diet in the direction of more whole plant foods and less animal-based foods and refined and processed products. Plant foods of course contain thousands of phytonutrients, antioxidants, vitamins and minerals that all act together in symphony to bring about health and combat disease. We do not at the present time know what these all are, but few experts debate the importance of a diet high in fruits and vegetables to reduce cancer risk. My contention is that a diet consisting entirely of fruits, vegetables and other whole plant foods such as nuts, seeds, whole grains and legumes, without any harmful animal-based foods at all, offers human beings the best hope for good health and a long life free of cancer and other chronic diseases that are causing so much suffering in our society today.

Why aren’t you anaemic, wasting away, or dead?
Don’t know. I should be, if you believe everything you read, but these days I could take your eye out with my nails – they are so hard I keep injuring myself. I’ve taken up running, hot yoga and Five Rhythms dance, and all my spots are gone.

Is it not really difficult at dinner parties?
Depends if you have nice friends or not. I have nice friends.

You’re wearing leather shoes.
No I’m not. But if I was, I would just say that we can all only do what we can do at any given time. We must each decide for ourselves how far we are willing or able to go. Anything we can do to reduce our overall consumption of animal products is a good thing. Meat-free Mondays have become quite popular in this regard.

You have a leather wallet.
No I don’t. But I will just say that there is a distinction to be made between those who identify as ethical vegans (and subsist on chip butties) and those who identify as dietary vegans (motivated by health). A whole-food, plant-based (WFPB) diet (with or without the addition of small amounts of animal products), in which more than 90% of total calories are derived from whole plant foods, is always going to be far healthier than the chip buttie and vegan chocolate diet. In my view, a whole population move in the direction of WFPB is infinitely preferable to a tiny minority of individuals upholding a strict ethical line while everyone else ignores them and gets on with eating what they like. So plant-based is probably a better term than vegan, which carries a lot of stigma.

I’m not doing a vegan option at the wedding, y’know.
No problem, I’ll bring my own.

You look like you’ve lost too much weight: here, have some cake. No mum, I haven’t actually lost any weight. Yes you have. I’m a mother and I know these things.
I got fat eating too much vegan cake. I don’t do that so much any more – it’s not good for you. Most of us today, unless we are very athletic, have a higher body fat percentage than is ideal, and our concept of what is normal is massively skewed. Our mothers love us and only want the best for us, but they have been subjected to a lifetime of misinformation. Be kind to your mum, but stick to your guns.

Why, then, are you a low fat raw vegan?
I want to live the most compassionate life that I can, for as long as I can. Fortunately, the two come as a package.

References:

  • [i] The Blue Zones (second edition): 9 lessons for living longer from the people who’ve lived the longest. Dan Buettner. National Geographic Society 2012. Also see ‘The Blue Zones’: http://kidseatplants.com/2014/07/the-blue-zones/
  • [ii] ‘Can Lifestyle Changes Reverse Coronary Heart disease? The Lifestyle Heart Trial’. Ornish et. al. Lancet Vol.336, No.8708; p129-133, and ‘Intensive Lifestyle Changes for Coronary Heart Disease’. Ornish et al. JAMA, December 16 1998, Vol.280, No.23; p.2001-2007. Also see: http://kidseatplants.com/2014/01/the-lifestyle-heart-study/
  • [iii] A Way to Reverse CAD? Caldwell B. Esselstyn et al. The Journal of Family Practice, July 2014;Vol.63,No.7:p356-364. Also see: http://kidseatplants.com/2014/12/a-way-to-reverse-coronary-artery-disease/
  • [iv] Vegetarian Dietary Patterns and Mortality in the Adventist Health Study 2. Orlich et al. JAMA Intern Med. 2013 Jul 8;173(13):1230-8
  • [v] A good summary of the features of apes and their natural diets can be found here: http://australianmuseum.net.au/humans-are-apes-great-apes
  • [vi] The Food Revolution: How Your Diet Can Help Save Your Life and Our World. John Robbins. Conari Press 2001. P97-112
  • [vii] The China Study. T. Colin Campbell and Thomas M. Campbell. BenBella Books 2006.
  • [viii] Becoming Vegan: The Complete Guide to Adopting a Healthy Plant-Based Diet. Brenda Davis and Vesanto Melina. Book Publishing Company 2000. P89-102
  • [ix] The China Study. T. Colin Campbell and Thomas M. Campbell. BenBella Books 2006.
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