This book is a well reasoned account of the essential role of Enzymes in human and animal nutrition.
It begins by outlining the basic thesis of the author, that humans have a limited enzyme potential, and when this is exhausted life ceases. In this way he equates enzymes with life force.
Howell then goes on to draw examples from animal physiology, and research to illustrate his points.
This book is written to be accessible to the lay person, so those looking for the kind of rigour to be found in a peer reviewed Journal should look elsewhere. Although much of the research is quite old, this does not diminish its relevance or its impact.
The logic underlying some of Howell's ideas is appealing, and is supported by facts drawn from dietary and veterinarian sources. even if they have not always been studied directly.
The idea pancreas secretions adapt to to dietary needs fits with the idea that the body conserves energy and does not perform work beyond need. This leads to the idea that eating enzyme rich "living" foods conserves pancreatic enzymes. Since the pancreas has finite capacity to produce enzymes, this must increase the availability of metabolic enzymes.
This falls short of demonstrating that the body has a finite enzyme potential. But the fact that studies have shown enzyme production declines with age supports rather than refutes this hypothesis. This allied with the fact that the body uses enzymes from food, sparing its own digestive enzymes lends further credibility to this idea.
The role of the protease enzyme Cathepsin, in the digestion of meat provides an insight into the role of meat in the human diet. Raw meat contains this enzyme in abundance, and it acts to break down meat protein. It is present in all animals and serves to explain how carnivores can digest prey that are swallowed whole. Killer whales eating seals and snakes eating small mammals are cited.
Cooking meat destroys this enzyme, and places the burden of digestion on us. This illustrates the value of rare steak, which is kept for some time to allow the enzymes to act, or the practice of burying meat practised in some traditional cultures.
The value of fruit and vegetable enzymes is expanded upon in several places. It is noted that such enzymes are active at low PH (3-4) and therefore contribute to pre-digestion in the stomach.
Overall this book provides an interesting, enzyme centred perspective on the world of nutrition. This perspective provides excellent food for thought. It also highlights the value of living food and forms the basis for further study and research.