Tuesday, February 03, 2015

The big fat protein swindle

Not a week goes by, so it seems, without a new version of a high-protein diet popping up in the media. 'Getting enough protein' has become a national obsession. Self-styled diet gurus and personal trainers ascribe almost mythical properties to protein, describing it as a 'body-shaping nutrient' and 'the key to successful weight loss'.
Inevitably, those banging the drum for high-protein diets mean a high animal protein diet; they usually describe plant proteins as being 'incomplete' or 'low quality' - and of course plant proteins always come 'pre-packaged' by nature with carbohydrate, which the protein-pushers vilify as the cause of the current obesity epidemic.
Yet the undeniable fact is that obesity is rare in societies that eat a diet based on carbohydrate-rich plant foods; while in Western countries (and among the wealthy in developing countries, who have adopted a Western-style high-animal protein dietary pattern) rates of obesity are skyrocketing.

How can you get to the truth about protein? Let's examine some of the most prevalent protein myths.

Myth #1: You can't get enough protein without eating meat and other animal products

Actually, this one is pretty funny, when you think about it. The largest, strongest land animals on the planet - elephants, rhinoceroses, oxen, buffalo - eat nothing but plants. If a silverback gorilla, which weighs 200-300 kg but is up to 10 times as strong as an adult male, can maintain its bulk and strength on a diet of leaves, shoots and roots, what on earth are we worried about?
I find it alternately amusing and maddeningly irritating (depending on what mood I'm in) that personal trainers tell their clients - who are ordinary men and women who just want to lose weight and get fitter - that they need to eat animal protein 2 or 3 times a day to achieve their goals, when there are so many examples of top athletes, including:
  • Bodybuilders Jim Morris, Billy Simmonds and Patrik Babouminan;
  • Ultra Men Rich Roll and Scott Jurek;
  • Triathlete Ruth Heidrich;
  • Runners Carl Lewis, Fiona Oakes and Ellen Jaffe Jones;
  • Fighters Mac Danzig and Emily Jans; and
  • Cricketer Peter Siddle and American football fullback Tony Fiammetta,
who have maintained peak physical fitness, strength and endurance on vegan (all-plant) diets.

Myth #2: Plant proteins are incomplete

It is completely astonishing to me that this myth is still stated as fact by so many people who ought to know better, including many dietitians.
For those who aren't familiar with the technicalities of protein, there are 22 amino acids that, arranged in different sequences, form all the proteins in our bodies. 8 of them (some authorities say 9) have to be obtained through the diet and are called essential amino acids, while the remainder can be made from the essential amino acids and other precursors, and are called non-essential amino acids.

Note that non-essential amino acids are every bit as important to protein formation as the essential ones; the tag 'essential' just means that it's essential to obtain them from the foods we eat because we can't make them ourselves.

Many diet books, websites and nutrition professionals still describe plant proteins as 'incomplete', meaning they are lacking in one or more essential amino acids, and state that we MUST eat different sources of plant proteins (e.g. grains and beans, or grains and nuts) at the same meal so we can obtain enough of all the essential amino acids. This is, quite frankly, complete rubbish.

All plants synthesise all the amino acids we use to build our body proteins. Animals are reliant on eating plants, or eating animals that have eaten plants, to get their amino acids.
All plant proteins contain all 8 essential amino acids as well as all of the non-essential ones. The proportion of the essential amino acids varies in plant foods (as it does in animal-derived foods) - for example, grains tend to have lower concentrations of lysine, and legumes have lower methionine, in relation to the other essential amino acids.
However, these so-called limiting amino acids are completely irrelevant, because if you eat enough legumes or grains to meet your energy (calorie/kilojoule) needs, you simply cannot fail to secure enough of each individual amino acid.

Your brilliant, highly-evolved body also has important strategies to maintain a consistent ratio of the amino acids needed for protein synthesis in your bloodstream: It recycles your own body proteins.

The cells lining your intestinal tract are sloughed off regularly, and go into the mixture of food working its way through your intestines, to be digested, absorbed and recycled into other body proteins. Used-up digestive secretions meet the same fate.
This recycling of endogenous ('from the inside') protein ensures that no matter what you eat at any given meal, the ratio of amino acids in your bloodstream after that meal will remain virtually identical.

In fact, we utilise much more recycled protein that 'fresh' dietary protein: we produce around 200 grams of endogenous protein per day, while most people eat less than 100 grams of dietary protein per day (1).

Myth #3: You need to eat more protein to lose weight/carbohydrates make you fat

If you are overweight, you have eaten too many calories for your needs. It's that simple. Protein and carbohydrate yield 4 calories per gram, while fat contains 9 calories per gram. If you eat too much of any of these macronutrients, you will gain weight or find it impossible to lose it.

Doing complicated calculations to achieve a precise ratio of proteins:fats:carbohydrates won't change the fact that you're taking in more energy than you're burning off. Instead, keep your focus on micronutrient-per-calorie-density, or maximising the amount of vitamins, minerals, antioxidants and other phytochemicals you obtain per calorie - what I call 'maximum nutrient bang for your calorie buck'.

Although I'm not an advocate of starch-based diets (because they supply insufficient micronutrients for optimal health) it's quite hilarious to blame starches for making people fat. Asian people have traditionally eaten large quantities of rice and remained slim. It's only when they migrate to urban areas of their own countries, or to other countries, and start eating more animal-based foods, that they become overweight.

A study of over 10 000 American adults (2), conducted by researchers employed by the US Department of Agriculture (a body which has advocated the consumption of copious amounts of animal-derived foods since it was founded), found that those who consumed the greatest percentage of their daily calories as carbohydrate, ate fewer calories overall and had the lowest body mass index (BMI) - that is, they were the slimmest. So much for carbs making you fat!

Myth #4: Your blood type determines your protein requirement

The popularity of Peter D'Adamo's blood type diet is staggering. What's even more staggering is the complete lack of scientific evidence for the dietary recommendations D'Adamo makes.

I could go on and on about the glaring scientific errors in his books, including:
  • The claim that type Os are predisposed to hypothyroidism because they don't make enough iodine (duh!!!! Iodine is a mineral - no one makes it, we have to consume it in our diet);
  • The fact that there is no biochemical research that supports his claim that lectins in food react differently with the A, B and O antigens; and
  • His assertion that agglutination reactions he has observed with blood taken from people and mixed with lectins that have not undergone the processes of digestion, would also happen in vivo i.e. inside the living body - for which there is no evidence whatsoever.
Neither D'Adamo nor any of his followers have ever published any scientific trials of the blood type diet.

But for me, the most damning piece of evidence against the blood type diet is the falsity of the claims D'Adamo makes about the sequence of development of the type O, A, B and AB blood groups, and the context of that development. His entire theory rests on the claim that all of our ancestors were meat-eaters with type O blood; that the A type developed after humans learned to cultivate crops; and the B and AB types appeared much later in our evolution (less than 10 000 years ago).

This is absolute bunkum. Chimpanzees and gorillas also have the ABO blood groups, indicating that these blood groups have been in existence in our evolutionary tree for at least 5 million years (and by the way, in case you hadn't noticed, chimps and gorillas have never cultivated crops or domesticated animals to consume their milk).
Paleoanthropologists are in complete agreement that our earliest hominid ancestor, was herbivorous (vegetarian), and there is widespread agreement that the A type developed first (3).

Protein facts

Protein is undeniably an important nutrient, and it is also undeniable that you can get perfectly adequate quantity and quality of protein on a diet that includes no animal products whatsoever, if you so choose.

Relax about protein, and put your focus on obtaining maximum nutrients per calorie by basing your diet on green and other non-starchy vegetables, legumes, fruits, nuts and seeds.