Paleo f(x) Austin 2014
How to Answer a Paleo Critic
Speaker : Chris Kresser
- Be respectful and don’t push
- Acknowledge that we were all in the position of a Paleo critic at some point
- Acknowledge what is true in the critique of Paleo and establish common ground
- Recognise that old myths die hard but things will eventually change
- We must ruthlessly challenge our own hypothesis. For instance with legumes, there is growing evidence that ancestors ate these. The lectins can be broken down by heat and other plant forms such as courgettes, strawberries and melons have more lectins than legumes. The Phytic acid inhibits mineral absorption, but foods such as spinach, chard, walnuts and almonds are also high in phytic acid
‘Paleolithic people were dead by the age of 30′
This doesn’t take into account the fact that there was 30 times more infant mortality, 100 times more childhood mortality, they were subject to the elements, traumatic injuries and difficult childbirth, as well as high levels of violence, all of which reduced the average lifespan. When they survived these events, they went on to live long lives. The current US life expectancy is 78 years. This happened in spite of changes in lifestyle. When modern hunter-gatherers have access to modern medicine (the most rudimentary kind), they live to an average of between 68-78 years. If they get to 45 they can expect to live to late 70s with no diabetes, heart disease, allergies or asthma.
We are in a position to take the best of both – a diet and lifestyle of the hunter-gatherere combined with modern medicine (emergency care, trauma, drugs).
‘Humans are still evolving’
Our genetics are largely the same as Paleolithic ancestors, however evolution is occurring 100 times faster than before. For instance with dairy, some have evolved to produce the lactase required to break down lactose. If there is no reason to produce this after weaning, then lactase levels drop.
After the advent of agriculture, Vitamin D and calcium deficiency resulted in shorter people. Dairy provided a much-needed nourishment and those able to digest milk were therefore favoured by natural selection. Thses evolutionary changes are relatively small and only affect a sub-set of the population. Although we may have evolved to tolerate foods such as dairy and legumes it is still true that agricultural foods are far more likely to cause an adverse reaction in the body. Why do we never hear about blueberry intolerance?
‘There is no evidence in favour of a Paleo diet’
There are not as many randomised, clinical trials as the Meditteranean diet but we do have the following lines of evidence:
- Archaeological studies – we know that fossil remains changed. As a result of the transition from hunter-gatherers to agriculturalists we know that people shrank (an average of 6 inches for men and 5 inches for women). This was a reflection of nutritional status
- Anthropological studies – contemporary hunter-gatherers are lean, fit and healthy. Obesity is unheard of and there is no diabetes, Alzheimers etc. they are superior in every measure of health and fitness
- Biochemical studies – we know that the nutrient density of foods on a Paleo diet far outsrips any other way of eating
- Randomized clinical trials – we have some small studies that are very promising. The Paleo diet is also much more satiating than the Medittereanean diet
‘Paleo is not nutritionally complete’
Paleo exceeds all nutrient requirenments except for Calcium (of which it provides 69%). There is Calcium in oily fish (eat preferably two times per week or more), bone broth and limited dairy if it suits you. Calcium needs are lower when magnesium and vitamin K2 are sufficient. On official government charts, any food that is high fat is automatically lowered on the nutrient density scale! Organ meats come out on top (see here). Herbs and spices and cacao are also high.We also need the anti-oxidants in fruit and vegetables.
Do we need grains to be healthy? No!
- They are low on the nutrient density scale
- 80% of grains are processed and refined
- They are low in bioavailability of nutrients
- If you really want to add them back in then prepare them properly but they are not required for human health
‘High protein diets are dangerous’
High protein diets can be harmful with a pre-existing kidney disease. A high protein diet pushes the kidney to hyper-filtrate but this is just an adaptive change as capacity increases to deal with high protein. The recent claim that high protein diets are as harmful as smoking focused on the increase in IGF-1 which may lead to cancer. High levels of methionine (an amino acid found in lean protein) may also increase cancer risk. However this is mitigated by eating glycine found in skin, cartilage, bone, oxtail etc. the effects are balanced. The lesson is that we need to eat from nose to tail!
‘The high amounts of saturated fat are harmful’
Some people do not thrive on a high fat diet and it is important to tailor Paleo according to your own requirements. Despite this, there is absolutely no link in studies between a high fat diet and heart disease.
‘Paleo is dangerous because it doesn’t restrict red meat’
People say that red meat is inflammatory because of the arachidonic acid. However it is anti-inflammatory and trials have found no link between arachidonic acid and inflammation. People who eat red meat on average tend to be unhealthier and therefore confounding factors are at work. We need to separate the facts out. Trials have not shown that red meat specifically causes colorectal cancer as there are so many confounding factors.
Is there an accumulation of environmental toxins in organ meat? Toxins tend to accumulate more in fat tissue and therefore it is most important to eat pasture-raised meat.
The most important thing to look at is changes in gut bacteria:
- How is this nourishing me?
- How is this nourishing my gut?
The Ornish diet also includes stress management, exercise, sleep management, elimination of processed foods, all of which lead to big improvements in health. The question is would they get even better on Paleo and the answer is yes! On an Ornish diet, nutrient deficiency would develop over time, whereas on Paleo nutrient density and inflammation are controlled.
For many vegetarians who go Paleo, they can experience low stomach acid and they have lost their ability to break down and digest food resulting in bad gut health, acne etc.