"During the last two decades a variety of food protein fragments has been demonstrated to elicit biological effects in various in vitro or in vivo test systems. A considerable part of these bioactive peptides are opioid receptor ligands , which may be regarded as exogenous supplements to the endogenous opioidergic systems of the human organism. Most of these foodderived opioid receptor ligands are fragments of the milk proteins alpha-, beta- or kappa-casein, alpha-lactalbumin, beta-lactoglobulin or lactotransferrin; however, also wheat gluten, rice albumin, bovine serum albumin or hemoglobin, i.e. possible constituents of meat, and even a protein from spinach could be demonstrated to contain fragments behaving like opioid receptor ligands. Practically all of these compounds display opioid agonist activity; only very few of them behave like opioid antagonists. Bioactive food protein derivatives have been termed “ food hormones”, which implies that these compounds display their bioactivities when released from food constituents, i.e. from their precursor molecules due to the action of gastrointestinal enzymes. The critical point in case of food protein-derived opioid receptor ligands is that only a minority of their bioactive effects demonstrated as yet has been observed upon oral or intragastric administration of these peptides or their precursor proteins and that most of these studies have been performed in animals. Thus, in terms of “evidence-based dietary supplementation” more studies are needed to prove effects of food protein-derived opioid receptor ligands or their precursors after oral administration in humans and, moreover, to prove a benefit for the consumers organism."
The evolution of the human diet over the past 10,000 years from a Paleolithic diet to our current modern pattern of intake has resulted in profound changes in feeding behavior. Shifts have occurred from diets high in fruits, vegetables, lean meats, and seafood to processed foods high in sodium and hydrogenated fats and low in fiber. These dietary changes have adversely affected dietary parameters known to be related to health, resulting in an increase in obesity and chronic disease, including cardiovascular disease (CVD), diabetes, and cancer. Some intervention trials using Paleolithic dietary patterns have shown promising results with favorable changes in CVD and diabetes risk factors. However, such benefits may be offset by disadvantages of the Paleolithic diet, which is low in vitamin D and calcium and high in fish potentially containing environmental toxins. More advantageous would be promotion of foods and food ingredients from our ancestral era that have been shown to possess health benefits in the form offunctional foods. Many studies have investigated the health benefits of various functional food ingredients, including omega-3 fatty acids, polyphenols, fiber, and plant sterols. These bioactive compounds may help to prevent and reduce incidence of chronic diseases, which in turn could lead to health cost savings ranging from $2 to $3 billion per year as estimated by case studies using omega-3 and plant sterols as examples. Thus, public health benefits should result from promotion of the positive components of Paleolithic diets as functional foods."