All posts tagged paleo

There was a large shift in our ancestors diet about 3.5 million years ago to food derived from grasses and/or sedges. This has potentially important implications for what diet we’re adapted to. Unfortunately, the evidence isn’t specific enough to be very useful:

The isotope method cannot distinguish what parts of grasses and sedges human ancestors ate – leaves, stems, seeds and-or underground storage organs such as roots or rhizomes. The method also can’t determine when human ancestors began getting much of their grass by eating grass-eating insects or meat from grazing animals.

Book review: Paleofantasy: What Evolution Really Tells Us about Sex, Diet, and How We Live, by Marlene Zuk

This book refutes some myths about what would happen if we adopted the lifestyle of some imaginary hunter-gather ancestor who some imagine was perfectly adapted to his environment.

I’m a bit disappointed that it isn’t as provocative as the hype around it suggested. It mostly just points out that there’s no single environment that we’re adapted to, plus uncertainty about what our ancestors’ lifestyle was.

She spends a good deal of the book demonstrating what ought to be the well-known fact that we’re still evolving and have partly adapted to an agricultural lifestyle. A more surprising point is that we still have problems stemming from not yet having fully evolved to be land animals rather than fish (e.g. hiccups).

She provides a reference to a study disputing the widely held belief that the transition from hunter-gatherer to farmer made people less healthy.

She cites evidence that humans haven’t evolved much adaptation to specific diets, and do about equally well on a wide variety of diets involving wild foods, so that looking at plant to animal ratios in hunter-gather diets isn’t useful.

Her practical lifestyle advice is mostly consistent with an informed guess about how we can imitate our ancestors’ lifestyle (e.g. eat less processed food), and mainly serves to counteract some of the overconfident claims of the less thoughtful paleo lifestyle promoters.

Book review: Food and Western Disease: Health and nutrition from an evolutionary perspective, by Staffan Lindeberg.

This book provides evidence that many causes of death in developed nations are due to a lifestyle that is different from hunter-gatherer lifestyles.

His studies of existing hunter-gatherer societies show moderately good evidence that cardiovascular disease is rare, that aging doesn’t cause significant dementia, and shows weaker evidence of less cancer.

He has some vaguely plausible reasons for focusing on diet as the main lifestyle difference. I’m disappointed that he doesn’t mention intermittent fasting as a factor worth investigating (is it obvious from his experience that some hunter-gatherer societies don’t do this?).

He uses this evidence to advocate a mostly paleo diet, although with less fat than is often associated with that label.

Much of the book is devoted to surveying the evidence about other proposed dietary improvements, mostly concluding they don’t do much (or in the case of calorie restriction, might work by causing a more paleo-like diet).

I don’t have a lot of confidence in his ability to interpret the evidence.

He gives the impression that Omega-3 consumption has little effect on health, citing papers such as this review, whose abstract includes:

showed no strong evidence of reduced risk of total mortality (relative risk 0.87, 95% confidence interval 0.73 to 1.03)

I’d call that evidence for a moderately important benefit of Omega-3, and I consider it strong evidence in comparison to typical dietary studies, although it’s weak compared to the evidence that other scientific fields aim for.

One response from nutrition experts says:

The null conclusion of the Cochrane report rests entirely upon inclusion of one trial, DART 2.

A quick glance at recent publications from another author he cites (Mozaffarian) got me this:

Considerable research supports cardiovascular benefits of consuming omega-3 PUFA, also known as (n-3) PUFA, from fish or fish oil.

Excessive skepticism is probably better than hype, but it will discourage many people from reading it. Plus the style is somewhere in between a reference book and a book that I’d read from start to end.