We Only Eat What We Like – Part 2
For Abbreviations and References, please see the previous article, same title.
Good Digestion of Pleasurable Food may Prevent Cancer, and Alleviates Pain:
A group of the University of Leiden, in the Netherlands, studied the effect of vasoactive intestinal peptide (VIP), peptide histidine-methionine (PHM), and secretin on spontaneous cell-mediated cytotoxicity of peripheral blood mononuclear cells against tumor target cells [van Tol et al. 1991]. VIP stimulated cytotoxicity against CaCo-2 human colon cancer cells, whereas less effect was seen against K-562 erythroleukemia cells. Depletion of CD16+ natural killer cells almost completely abolished cytotoxicity and subsequent VIP incubation did not change residual activity. In contrast to
PHM, which hardly influenced cytotoxicity, secretin was found to be more effective especially against K-562 target cells. These observations suggest a modulating role for the neuropeptide VIP in the cellular immune response against tumor cells, especially from the colon, resulting in increased activity of CD16+ natural killer cells. Secretin seems to be less potent in modulating cellular cytotoxicity. These findings support the concept that gastrointestinal peptides can play a role in the regulation of cellular cytotoxicity against tumor cells, and, as mentioned earlier, palatability of food is a major stimulant of the secretion of these peptides. This should help the elderly who are more prone to malignancies. Indeed, taste and smell losses in the elderly can reduce appetite and lead to inadequate dietary intake. Although these chemosensory deficits are generally not reversible, sensory interventions including intensification of taste and odor can compensate for perceptual losses. One method for “treatment” of chemosensory losses involves sensory enhancement of foods with flavors and monosodium glutamate (MSG). Amplification of flavor and taste can improve food palatability and acceptance, increase salivary flow and immunity, and reduce oral complaints in both sick and healthy elderly. Studies, conducted by S.S. Schiffman , show the effects of sensory enhancement with flavors and/or MSG on food intake, satisfaction, immunity and salivation in the elderly. The results of these studies indicate that amplification of taste and smell can improve food palatability and acceptance, improve lymphocyte counts, increase salivary flow and increase secretion rate of salivary immunoglobulin A (sIgA). Eating flavor-enhanced foods also led to improvement in one anthropometric measure (grip strength). In another study, the elderly residents ate flavor-enhanced foods for 3 wk and the identical foods in unenhanced form for another 3 wk. Half of the subjects received enhanced food first and unenhanced food second; for the other half, the order was reversed. Six flavors were utilized throughout the study: roast beef, ham, natural bacon, prime beef, maple and cheese. These flavors were primarily odors; they were virtually tasteless and contained no NaCl or sweeteners. The immune and functional improvements (i.e., increased T and B cell counts and improved grip strength) found in the study occurred as a result of intensifying the flavor of some but not all foods at a meal. Subjects ate more of the flavor-enhanced foods and less of the unenhanced foods. As a consequence, they consumed the same macro- and micronutrients on the enhanced and unenhanced arms of the study. That is, they consumed the same nutrients on both arms of the study; the only difference between the foods consumed during the enhanced and unenhanced arms was the flavor level experienced by the subjects. Yet, flavor enhancement improved immunity and grip strength! Similar results were found in an additional study that used MSG and flavors to intensify both taste and smell simultaneously. The improved immune status produced by flavor enhancement may result from one or more of the following four possibilities. First, direct neural-immune connections exist between those parts of the brain that subserve olfaction and the immune system. Thus olfactory stimulation could boost immune function directly via these connections. Second, the elevated flavor levels may lead to greater release of digestive enzymes and produce better absorption of micronutrients. Third, there may be phytochemicals in the flavors that directly improve immunocompetence due to their biochemical actions. Fourth, flavor enhancement may improve mood, leading to reduced circulating cortisol: cortisol, the stress hormone, is known to suppress the immune status. The results of one experiment showed that application of sugar (taste alone) and flavor (taste and odor combined) to the tongue induced significantly higher secretion rates of sIgA than the application of water in both young and elderly subjects. In addition, flavor application produced significantly higher absolute concentrations of sIgA than sugar application alone. Secretion rates of sIgA in young persons were significantly higher than those in elderly persons. In another study, the increase in sIgA secretion rate for the elderly subjects at 30 and 60 min for each food with MSG was greater than that observed when the same food was consumed without MSG. The short-term increases in sIgA secretion rates in these two experiments may be due to the following: 1) the elevated salivary flow caused by reflex secretion of saliva containing sIgA, and 2) possible neural-immune interactions that induced elevated absolute concentrations of sIgA (in the flavor condition in the first experiment). Schiffman also tested flavor preferences in 13 patients who were undergoing or had recently completed chemotherapy (10 subjects) or radiotherapy (3 subjects) for breast cancer. In a single-blind study, patients were given two samples of a food to taste and were asked which one they preferred. For all items, the majority of cancer patients preferred the flavor-enhanced food to the unenhanced food. None of the patients reported an aversion to the foods that were tested. During testing, several cancer patients indicated that the odors reminded them of pleasant times in the past. Thus, flavor amplification might potentially reduce complaints about foods, not only because they improve sensory qualities, but because they trigger pleasant memories. Odor signals are processed in the “limbic system” of the brain, which also processes emotions and memories; furthermore this portion of the brain interacts with the immune system, which may be advantageous for cancer patients. These observations and concepts have been confirmed by others [Mathey et al. 2001]: adding flavor enhancers to the cooked meals was an effective way to improve dietary intake and body weight in elderly nursing home residents, in the Netherlands. With the right choice of condiments, seasonings or sauces, ordinary food can go from “blah” to “ahh!” –with a boost in nutritional value. Condiments give a chance to be adventurous and to taste other cuisines without leaving home; tandoori sauce, barbeque sauce or spicy brown mustard takes your meal to India, Texas or Germany. The condiments we choose are only limited by our imagination [Fitch-Hilgenberg 2007]. Indeed, nutrition –and pleasure of eating- is a major factor influencing immunity in the elderly [Lesourd 2004]; in seniors, decreased T-cell, B-cell subsets and functions, and innate immunity are all strongly related to protein nutritional and micronutrient status. Stress after stress, and anhedonia at meals, pushes the elderly to frailty.
Herbs and spices have a traditional history of use, with strong roles in cultural heritage, and in the appreciation of food and its links to health. Demonstrating the benefits of foods by scientific means remains a challenge, particularly when compared with standards applied for assessing pharmaceutical agents. Pharmaceuticals are small-molecular-weight compounds consumed in a purified and concentrated form. Food is eaten in combinations, in relatively large, unmeasured quantities under highly socialized conditions. The real challenge lies not in proving whether foods, such as herbs and spices, have health benefits, but in defining what these benefits are and developing the methods to expose them by scientific means. The place of herbs and spices in the diet needs to be considered in reviewing health benefits. This includes definitions of the food category and the way in which benefits might be viewed, and therefore researched. Research may focus on identifying bioactive substances in herbs and spices, or, in tune with reality, on their properties as a whole food, and/or be set in the context of a dietary cuisine. The antioxidant properties of herbs and spices are of particular interest in view of the impact of oxidative modification of low-density lipoprotein cholesterol in the development of atherosclerosis. There is level III-3 evidence (National Health and Medical Research Council [NHMRC] levels of evidence) that consuming a half to one clove of garlic (or equivalent) daily may have a cholesterol-lowering effect of up to 9%. There is level III-1 evidence that 7.2 g of aged garlic extract has been associated with anti-clotting (in vivo studies), as well as modest reductions in blood pressure (an approximate 5.5% decrease in systolic blood pressure). A range of bioactive compounds in herbs and spices have been studied for anti-carcinogenic properties in animals, but the challenge lies in integrating this knowledge to ascertain whether any effects can be observed in humans, and within defined cuisines. Research on the effects of herbs and spices on mental health should distinguish between cognitive decline associated with aging and the acute effects of psychological and cognitive function. There is level I and II evidence for the effect of some herbal supplements on psychological and cognitive function. There is very limited scientific evidence for the effects of herbs and spices on type 2 diabetes mellitus, with the best evidence being available for the effect of ginseng on glycemia, albeit based on four studies. More research is required, particularly examining the effects of chronic consumption patterns. With increasing interest in alternatives to non-steroidal anti-inflammatory agents in the management of chronic inflammation, research is emerging on the use of food extracts. There is level II evidence for the use of ginger in ameliorating arthritic knee pain; however, the improvement is modest and the efficacy of ginger treatment is ranked below that of ibuprofen. In addition to delivering antioxidant and other properties, herbs and spices can be used in recipes to partially or wholly replace less desirable ingredients such as salt, sugar and added saturated fat in, for example, marinades and dressings, stir-fry dishes, casseroles, soups, curries and Mediterranean-style cooking. Vegetable dishes and vegetarian options may be more appetizing when prepared with herbs and spices. As several metabolic diseases and age-related degenerative disorders are closely associated with oxidative processes in the body, the use of herbs and spices as a source of antioxidants to combat oxidation warrants further interest; and as with most foods, the real benefits of including them in the diet are likely to emerge with a better understanding of the attributes of health that are best supported by food, and in methodological developments addressing the evidence base for their effects. These developments are well underway through evidence-based frameworks for substantiating health claims related to foods. With time, we can expect to see a greater body of scientific evidence supporting the benefits of herbs and spices in the overall maintenance of health and protection from disease [Tapsell et al. 2006].
Sugars and fat play a unique role in the human diet [Drewnowski 1995]. The selective choice of sugars and fat as chief energy sources seems to be influenced less by the body’s energy needs than by the sensory appeal of sweet and fat-rich foods. This appeal typically holds not only across individuals, but also across cultures. Although many behavioral, social, and cultural factors play major roles in diet selection, people respond primarily to the sensory qualities of food (“We eat only what we like”). Some clinical studies have reported that individual food choices, and therefore the macronutrient composition of the diet, are influenced directly by the central nervous system. However, broader population-based studies point to the central role of taste in determining food selection. Survey studies have shown that the global consumption of sugars and fat is further determined by such variables as income, socioeconomic status, and the availability of sugars and fat in the food supply. Nutrition intervention strategies aimed at promoting dietary change in communities ought therefore to consider not only physical health, but also, and most importantly, the sensory pleasure response, and a wide range of demographic, economic, and sociocultural variables.
An increasing proportion of food consumption appears to be driven by pleasure, not just by the need for calories. The food environment may be creating an appetitive counterpart to the psychological effects of other hedonically-driven activities such as drug use and compulsive gambling. Homeostatic (i.e., eating because of physical need) and hedonic (eating for pleasure in the absence of need) eating motives overlap but are nonetheless separable. Some individuals may experience frequent thoughts, feelings and urges about food in the absence of any short-or long-term energy deficit. Delicious food can itself create powerful motives to keep eating it, much like more traditional addictive substances. In environments where such foods are always available, such motives may continue to manifest themselves in food-related thoughts and urges even when we are away from food. The smell of freshly baked doughnuts can entice someone to stop at a bakery and eat the doughnut or the sight of a dessert can attract a person to eat even when physically full after dinner. Once such habits are firmly established, trying to change them may not be a matter of “just saying no;” rather, such discontinuation may produce withdrawal responses. Traditionally, it has been thought that food is a form of self-medication for stress or boredom, but we should look beyond psychological factors when studying the facts behind superfluous eating. For one, rather than viewing such eating as pure indulgence, eating for pleasure may have been an evolutionary adaptation that helped us survive periods of food scarcity in the distant past. Palatable foods may create powerful motivations to eat not only because their taste is rewarding but because their consumption prevents the anxiety or stress that would occur if they were not consumed. Most normal-weight restrained eaters are trying to control their food intake not to lose weight but to prevent overeating and weight gain. It is logical to expect that the combination of susceptibility toward overeating and conscious efforts to avoid overeating would result in more frequent instances of “hedonic hunger” [Lowe et al. 2007].
Palatable sweet ingestion produces a morphine-like analgesia in both rats and human infants. To determine whether palatable sweet ingesta induces antinociception in human adults, 60 Canadian university [Mercer et al. 1997] students (30 men, 30 women) were exposed to a pressure algometer both before and after consuming either a sweet soft drink, filtered tap water, or nothing (Experiment 1). Pain responsivity was assessed with four pain measures: threshold, tolerance, and visual analogue scale (VAS) ratings of intensity and unpleasantness. Results showed that women who consumed either soft drink or water reported increased pain tolerance and VAS ratings at post-treatment compared with those receiving nothing. However, differences between groups were not found for men. Moreover, compared to men, women reported lower pain thresholds and tolerances and rated the pain as more intense. In Experiment 2, 40 women consumed either nothing or foods that they rated previously as palatable (chocolate-chip cookies), unpalatable (black olives), or neutral (rice cakes). Women who consumed the palatable sweet food showed increased pain tolerance compared with those receiving the unpalatable food, the neutral food, or nothing. These data demonstrated that “palatability-induced antinociception” (PIA) occurs in human adults.
Recent studies have demonstrated what we suspected: the cannabinoids we make enhance sweet taste. Endocannabinoids act in the brain to increase appetite and modulate taste receptors on the tongue to increase response to sweets, with no effect on sour, salty, bitter or umami taste. They are also found in intestine & pancreas helping nutrient absorption, insulin secretion and energy metabolism, and demonstrate an opposite action to leptin [Yoshida et al. 2009].
Glucagon-like peptide-1 (GLP-1), released from gut endocrine L cells in response to glucose, regulates appetite, insulin secretion, and gut motility. Glucose given orally, but not systemically, induces GLP-1 secretion. Human duodenal L cells express sweet taste receptors, the taste G protein gustducin, and several other taste transduction elements. The human L cell line NCI-H716 expresses -gustducin, taste receptors, and several other taste signaling elements. GLP-1 release from NCI-H716 cells was promoted by sugars and the noncaloric sweetener sucralose, and blocked by the sweet receptor antagonist lactisole or siRNA for -gustducin. L cells of the gut “taste” glucose through the same mechanisms used by taste cells of the tongue. Modulating GLP-1 secretion in gut “taste cells” may provide an important treatment for obesity, diabetes and abnormal gut motility [Jang et al. 2007].
But fat might not be that guilty; in fact fatty foods curb hunger! Feeding stimulates small-intestinal mucosal cells to produce the lipid messenger oleoyleethanolamide (OEA) which decreases meal frequency. Duodenal infusion of fat stimulates OEA mobilization in the proximal small intestine, whereas protein or carbohydrates don’t. Activation of small-intestinal OEA mobilization, enabled by uptake of dietary oleic acid, serves as molecular sensor linking fat ingestion to satiety [Schwartz et al. 2008].
Chocolate Beats Prozac®:
Although addictive behavior is generally associated with drug and alcohol abuse or compulsive sexual activity, chocolate may evoke similar psychopharmacologic and behavioral reactions in susceptible persons. A review of the literature [Bruinsma et al. 1999] on chocolate cravings indicates that the hedonic appeal of chocolate (fat, sugar, texture, and aroma) is likely to be a predominant factor in such cravings. Other characteristics of chocolate, however, may be equally as important contributors to the phenomena of chocolate cravings. Chocolate may be used by some as a form of self-medication for dietary deficiencies (e.g. magnesium) or to balance low levels of neurotransmitters involved in the regulation of mood, food intake, and compulsive behaviors (e.g. serotonin and dopamine). Chocolate cravings are often episodic and fluctuate with hormonal changes just before and during the menses, which suggests a hormonal link and confirms the assumed gender-specific nature of chocolate cravings. Chocolate contains several biologically active constituents (methylxanthines, biogenic amines, and cannabinoid-like fatty acids), all of which potentially cause abnormal behaviors and psychological sensations that parallel those of other addictive substances. Most likely, a combination of chocolate’s sensory characteristics, nutrient composition, and psychoactive ingredients, compounded with monthly hormonal fluctuations and mood swings among women, will ultimately form the model of chocolate cravings. Dietetics professionals must be aware that chocolate cravings are real. The psychopharmacologic and chemosensory (beneficial) effects of chocolate must be considered when formulating recommendations for overall healthful eating and for treatment of nutritionally related health issues.
A recent study included 11 volunteers who classified themselves as “chocolate desiring” and 11 other who were “chocolate indifferent”. In this controlled clinical study, each subject –all men- ate chocolate or placebo over a five day period while their blood and urine samples were extensively analyzed. The “chocolate lovers” had a hallmark metabolic profile that involved low levels of LDL-cholesterol (the “bad” one), and marginally elevated levels of albumin (beneficial). The chocolate lovers expressed this profile even when they ate no chocolate. The activity of the gut microflora in the chocolate lovers was also distinctly different from those in the chocolate indifferent group. Food preference, e.g. chocolate, might be programmed or imprinted into our metabolic system (nutrimetabonomic) in such a way that the body becomes attuned to a particular diet. This imprinting is independent of the ingested food, as chocolate consumption versus placebo had no direct effect [Rezzi et al. 2007].
Dark chocolate controlled anxiety, depression and stress, and restored health in a free living group [Martin et al. 2009]. The study explored the metabolic responses of free living subjects to a daily consumption of 40 g of dark chocolate for up to 14 days. A clinical trial was performed on a population of 30 human subjects, who were classified in low and high anxiety traits using validated psychological questionnaires. Biological fluids (urine and blood plasma) were collected during 3 test days at the beginning, midtime and at the end of a 2-week study. NMR and MS-based metabonomics were employed to study global changes in metabolism due to the chocolate consumption. Human subjects with higher anxiety trait showed a distinct metabolic profile indicative of a different energy homeostasis (lactate, citrate, succinate, trans-aconitate, urea, proline), hormonal metabolism (adrenaline, DOPA, 3-methoxy-tyrosine) and gut microbial activity (methylamines, p-cresol sulfate, hippurate). Dark chocolate reduced the urinary excretion of the stress hormone cortisol and catecholamines, and partially normalized stress-related differences in energy metabolism (glycine, citrate, trans-aconitate, proline, beta-alanine), and gut microbial activities (hippurate and p-cresol sulfate). These results provides strong evidence that a daily consumption of 40 g of dark chocolate during a period of 2 weeks is sufficient to modify the metabolism of free living and healthy human subjects, as per variation of both host and gut microbial metabolism.
Wine is Health, Medicine, Pleasure, and More:
Wine has been part of human culture for >6,000 years, serving dietary and socio-religious functions. It contains a range of polyphenols that have desirable biological properties; these are 5 times higher in wine than in fresh grapes; fermentation dissolves them into wine. Catechin and epicatechin peak at about 2 hours, and half-life is about 4 hours, suggesting that regular ingestion, with food, is good. Indeed, wine may confer protection against adverse effects of some foods [Renaud et al. 1998].
The list of activities of plant and wine flavonoids did not include effects on the central nervous system (CNS) up to 1990, when Paladini et al.  described the existence of natural anxiolytic flavonoids. The first of these was chrysin (5,7-dihydroxyflavone), followed by apigenin (5,7,4′-trihydroxyflavone) and flavone itself. Semisynthetic derivatives of flavone obtained by introducing halogens, nitro groups or both in its molecule, give rise to high affinity ligands for the benzodiazepine receptor, active in vivo; 6,3′-dinitroflavone, for example, is an anxiolytic drug 30 times more potent than diazepam (Valium®).
Regular intake of red wine brings a better sex life to women: regular moderate intake of red wine is associated with higher Female Sexual Function Index (FSFI), vaginal lubrication and overall sexual function when compared to the teetotaler. It suggests a relationship between red wine consumption and better sexuality in women aged 18-50 [Mondaini et al. 2009].
But wine, or wine-derived molecules, is/are not primarily tranquilizer(s). Wine is first-and-above all Pleasure. As Robert M Parker Jr. says it [Langewiesche 2000] “Part of life is to live it and enjoy it, and seize the moment that you find particularly pleasing. ’Fettuccine Alfredo is dangerous for your health. Kung pao chicken will destroy your life’. Holy shit, the first week it’s one of the classics of Italian cooking, the next week it’s one of the staples of Chinese cooking! These are the people who do studies that your carry-out Chinese meals are saturated in fat…. I’d just like to meet them! I mean, what do they do for pleasure? Pleasure is defined by dining, and let us get rid of the Pleasure Police (CSPI) whose business is “the taboo of the week”.
But the enjoyment of wine is influenced by the shape of the wine glass. This is not only the demonstration done by Georg Riedel, but the result of a study [Huttenbrink et al. 2001] conducted on 99 healthy volunteers: egg-shaped glasses, compared to “tulip” or “beaker” glasses appear to deliver higher intensity and higher complexity of wine bouquet.
And that’s why wine lovers learn to taste. We know that the effort we put into understanding and appreciating wine–as opposed to simply enjoying it (or its psychotropic effects)–pays big dividends. Really tasting wine adds an extra dimension to the basic daily routines of eating and drinking. It turns obligation into pleasure, a daily necessity into a celebration of life [Matthews 1996].
Georges M. Halpern, MD, PhD
Distinguished Professor of Medicinal Sciences
The Hong Kong Polytechnic University
E-mail: [email protected]