Appetite Short News: Pavlovian Conditioning at Work in the Obese | Polydextrose as a Satiety Promoter | Parents, Just Like Their Kids, Fall for All the Tricks of the Food Industry

Too lean for Pavlovian Conditioning.

In today's "appetizing" installment of the short news, I have picked three of the latest publications from the scientific journal Appetite, of which I thought that they were newsworthy. In that, I cover the Pavlovian Conditioning of overweight individuals, the benefits of polydextrose on appetite control and the way product labels fool parents and children into buying unhealthy foods.

I have to admit: It's not all practically applicable, but who knows maybe you can use it to smart-ass during the holidays. Or maybe you bake some polydextrose enhanced super-satiating cookies for your family, ha?

More facts for your smart-ass sessions on the holidays ;-)

Bugs Dictate What You Crave

Sweeteners & Your Gut

Foods, Not Ma- cros for the Gut

Lactulose For Gut & Health

Probiotics Don't Cut Body Fat

The Macrobiotic MaPi2.0 Diet

• Hedonic food cue conditioning in the obese: You know the story about Pavlov's dog starting to salivate, when the bell rang that would usually accompany his next feeding?
  
  Well, a recent study confirms that something very similar is at work in obese, but not lean subjects. While the former remain calm and cool to a visual cue that had previously been given alongside some tasty chocolate milk, the latter began to swallow, a reliable sign of increased salivation. As the scientists from the Allaint International University in San Diego say, these "
  

  are the first results to show differential acquisition of Pavlovian conditioned responding in overweight individuals compared to lean individuals" (Meyer. 2014)

  The fact that the conditioning worked was yet not the only significant finding, Meyer et al. made. They also observed that hedonic food stimuli were significantly more effective 'conditioners' in the obese than neutral stimuli.
  
  Practically speaking the observations the researchers from the Allaint International University in San Diego made, may partly explain the difficulties obese individuals who may have been conditioned / conditioned themselves to hedonic food stimuli for their whole lives have when it comes to controlling their energy intake.
• Polydextrose as a satiety promoter: In their meta-analysis of the current literature on the effects of polydextrose on energy intake, researchers from the US and Finland found that...
  
  • polydextrose consumed with a mid-morning snack reduces energy intake (EI) at lunch time.
  • this reduction in EI at lunch time occurs in a dose-dependent manner.
  • but the energy intake during the rest of the day did not show any difference
  Now this probably wouldn't be newsworthy, then, if a a regression model had not been able to confirm a dose-dependent effect on the reduction of daily energy intake.

Added polydextrose reduces the insulin response to milk (Lummela. 2009)

What exactly is polydextrose? Polydextrose is a glucose polymer that is completely soluble in water. As a food additive it offers the texture of sucrose but provides only 25% of the equivalent energy, or 4 kJ/g. It has been approved for use in foods in over 60 nations and is recognized as a dietary fiber in more than 20 countries (FAO/WHO, 2009). Next to the reduced energy content it has another benefits of the fibrous substance is that its addition to foods like milk can reduce the insulinogenic response to this meals significantly - even in healthy individuals (Lummela. 2009).

• More specifically, the meta-analysis was able to show that the dose of polydextrose consumed correlated significantly with the reduction of nergy intake at lunch (−0.67 Polydextrose (g/day) | 80% correlation; P < 0.01), due to which the energy intake was reduced by 1% per 2.86g of polydextrose per day.
  
  As Ibarra et al. point out, the sex-specific results are consistent with results for the whole group - the effect is thus similarly pronounced in both men and women. Accordingly, the meta-analysis "supports the notion that the consumption of polydextrose reduces voluntary energy intake at a subsequent meal" and that "this reduction in energy intake occurs in a dose-dependent manner" (Ibarra. 2014).
• Parents of preschool children make (non-)sense of front-of-package visuals and claims on food - A recent study from the Colorado State University and the University of Illinois at Urbana-Champaign investigated what parents make of the colorful packaging of foods their kids like to buy and found that most of them tend to "accept misleading front-of-package claims when making quick food decisions" (Abrams. 2014).
  
  

  

  Parents fall for unwarranted claims, and misleading images children for cartoons.

  While playful visuals appeal to children, parents associate them with junk food. That does yet not mean that they would not fall for health claims, realistic graphics, and natural claims which make them classify the junkfoods that were investigated in the study at hand as healthier.
  
  Fruit graphics in particular were misunderstood to indicate that the respective foods actually contained fruit, when they were simply meant to communicate flavors, instead. Against that background it's not surprising that the unsettling result of this study in 28 women and 2 men revealed that "[parents may make unhealthy food choices as a result of front-of-package information" (Abrams. 2014).

Intensity is key to reduce the exercise induced increase in appetite | more

Bottom line: I understand very well that for most of you only news item #2 is of practical value. Item #1, on the other hand, is rather a description of the misery than a solution and #3 is something that you as a SuppVersity reader probably knew, already... that being said, simply adding more polydextrose to the foods dumb parents buy for their kids because there are fruits on the packaging is not going to help their kids becoming overweight adults who begin to salivate, whenever they see the right food cues. A long-term solution to the problem would thus have to start with the production of healthier foods by the food industry and the education of the public who would then no longer fall for the unwarranted health claims on the packaging of children and adult food products | Comment on Facebook!

References:

• Abrams, Katie M., Caitlin Evans, and Brittany RL Duff. "Ignorance is bliss: how parents of preschool children make sense of front-of-package visuals and claims on food." Appetite (2014).
• Ibarra, Alvin, et al. "Effects of polydextrose on different levels of energy intake: a systematic review and meta-analysis." Appetite (2014).
• Lummela, Netta, et al. "Effects of a fibre-enriched milk drink on insulin and glucose levels in healthy subjects." Nutrition journal 8.1 (2009): 45.
• Meyer, Monica D., et al. "Pavlovian conditioning to hedonic food cues in overweight and lean individuals." Appetite (2014).

Vitamin A Regrows Liver Tissue. Polydextrose Makes Dieting a Breeze. Exercise Blunts Negative Effects of High Fructose Diet. Diabetes Precipitates Female Sexual Dysfunction.

I did miss my own 1000-posts jubilee!

This week it's pretty easy to find the SuppVersity figure of the week. It's 1011 and that's the number of individual posts this "blog" currently holds. Actually, the very moment I hit the "publish" button on this one, it's going to be 1012 (see image on the right). I guess, I should have 'celebrated' that twelve posts before, but you know how I am, it's about the quality, not the quantity and though I am aware that the latter is unquestionably fluctuating, I would hope that each of you has found one or two 'pearls' - I mean, if you didn't why are you coming back regularly, then?

Apropos regularly, it's Saturday and thus about time for a couple of "On Short Notice" items. So let's not waste any time flattering and get to the science news business:

Vitamin A essential for liver regeneration. Plus: β-carotene and cancer even in non-smokers

So much for the vitamin A vs. D antagonism - in fact, one can't go without the other: Vitamin A & D synergize against liver cancer and increase survival rates by more then 75% (read more)

(Blaner 2013) -- Other than SuppVersity readers, the average slef-proclaimed health-conscious citizen probably thinks of (false) horror stories about vitamin A laden polar bear livers killing a handful of ravenous arctic explorers. The fact that the active form of vitamin A is actually one of the most important hormone-like substances in your body that's essential for the maturation process of stem cells, on the other had, got lost at least since vitamin D the supposed vitamin A antagonist became all the rage in the past decade. Scientists from the Coumbia University in New York and the Chernivtsi National University in Chernivtsi, Ukraine, are now going to publish a paper that should remind everyone (including the science community) that the contemporary black and white painting on D & A may well impair the progress we make in our understanding of our own physiology.

Missing half your liver? Not a problem if you got enough "liver building" vitamin A ;-)

In a mouse model which has been genetically modified so that the rodents weren't able to store adequate levels of retinoids  (yeah, there is a whole family of "vitamins A") in the liver, showed a delayed and incomplete regenerative response to partial hepatectomy (cutting away parts of the liver; PHE). As the scientists point out,

"[t]he requirement for proper retinoic acid signaling to allow for normal liver regeneration is underscored by studies of hepatocyte-specific RXRα-null mice [mice lacking the retinoid receptor]. When RXRα is ablated there is reduced hepatocyte lifespan, which is accompanied by premature hepatocyte death and the appearance of necrotic areas. RXRα ablation also results in delayed hepatocyte proliferation following PHE." (Blaner 2013)

At first sight this observation goes again the often cited liver-toxicity of vitamin A. In view of nature's favorite dose-response curve, which is bell-shaped and indicates that bad things (often similar or even identical ones) happen in both deficiency and toxicity states, it's only logical, though. Plus, similar effects have been observed for wound-healing decades ago (Gerber. 1982) and Ehrlich and Hunt report in a 1968 paper in the Annals of Surgery that the administration of vitamin A blunts the negative effects on cortisol on wound healing and appears to be necessary for optimal tissue regeneration (Ehrlich. 1968).

So, another good reason to pop vitamin A supplements?

Supplementation with very high doses of isolated beta-carotene could in fact induce a state of "vitamin A resistance" in response to the formation of a metabolite that blocks the RXR receptor just like a SERM like clomiphene citrate block the estrogen receptor (read more).

For a healthy person living on a paleo-esque diet supplements should not be necessary. The amount of vitamin A and its pre-cursor beta-carotene you get from a whole-foods diet is usually adequate, even if you don't consume liver or organ meat on a regular basis. The use of what you will generally get, when you go to a healthfood store and buy a "vitamin A" supplement, i.e. a high dose beta carotene, only, product is probably counter-indicated not just for smokers, where it appears to increase the risk of lung cancer development, but also in normal healthy individuals who usually get plenty of beta-carotene from the myriad of fortified foods your local supermarket has to offer - after all, one of the most recent meta-analyses showed that 20-30mg/day increase everyone's risk of lung cancer development by 16% and that of stomach cancer by 34% (Druesne-Pecollo. 2010).

Polydextrose has non-noticeable, but significant satiety effects

(Astbury. 2013) -- I know the headline sounds confusing, but basically that's the long and short of the results, Astbury, Taylor and MacDonald present in their most recent isse in the British Journal of Nutrition. The scientists fed 12 male and 9 female healthy university students (mean age 23.2y; BMI 22.3kg/m²) who had consumed identical breakfasts at 8:00am with isocaloric (210kcal) "preload" mid-morning snacks at 10:45am and 90min before they had a pasta-based test meal, of which they were supposed to eat as much as it would take to feel comfortably full.

Figure 1: Food intake (in kcal) after mid-morning snack with different amounts of polydextrose (left); caloric intake on the subsequent meals of the day (right; Astbury. 2013)

As the data in figure 1 indicates, the consumption of the liquid preload which contained either 0, 6.3, 12 or 21g of the sweet tasting polysaccharide that reaches the colon largely undigested, where 50% of the polydextrose molecules will be fermented to yield CO2 and volatile SCFA such as propionate and butyrate and the rest will be excreted intact in the feces lead to dose-dependent reductions in the amount of food that was consumed in the subsequent meal.

50% energy availability, a source of SCFA, tasty & easy to process - perfect diet 'food'?

With only 50% energy availability and 50% being fermented to short chain fatty acids (SFCA),  the 89% dextrose, 10% sorbitol & 1% percent citric acid molecule, polydextrose could actually be a better choice for dieters than WMHDP (learn more about the SCFA based fat burning effects of resistant starches and how to make fat burning pancakes)

Interestingly, the reduced energy intake was not brought about by a consciously noticeable reduction in either fullness, hunger or desire to eat in response to the test meal (the scientists assessed that by questionnaires). And despite the fact that the effect was only transient, it's actually good and important news that the men and women did not accommodate for the 12-23% (male participants) and 6-18% (female participants) reduction in energy intake on the subsequent meal.

If that worked with every meal and you could achieve a ~20% reduction in energy intake, this alone should help you shed some weight pretty effortlessly. And as if that was not enough, already the polydextrose drinks was even more palatable than the sugary original; with the highest polydextrose content being perceived as most "creamy" - bon appetit ;-)

Even shorter news - "On real short notice", so to say  ;-)

I am well aware that what began as short news has as of late turned into a bunch of regular news - well, almost. So I decided to try and cut the last two items in today's installment short, in order to have them fit into what you would actually expect from a "on short notice" ;-)

• Exercise nullifies bad effects of high fructose diet (Moraes-Silva. 2013) -- A paper by scientists from the University of Sao Paulo puts the "lack of exercise / insuficient activity" hypothesis of obesity back on the radar. Even with an otherwise highly detrimental liquid fructose overload of 100g/l in their drinking water, the rodents in the study Moraes-Silva et al. conducted, did have normal (within statistical limits) glucose tolerance, blood pressure and heart disease risk as the rodents in the sedentary and the exercised control groups.

  

  Figure 2: Regular exercise maintains insulin sensitivity, cardiovascular disease risk and blood pressure even in the presence of pathologically high liquid fructose ingestion (Moraes-Silva. 2013)

  The regular treadmill running also blunted the autonomic dysfunction that was characterized by "an approximate 50% decrease in baroreflex sensitivity and 24% in HR variability", as well as increases in sympathovagal balance (140%) and renal sympathetic nerve activity (45%). Now you tell me "it's all about diet", only. Let alone: "Exercise just makes you hungry!"

• Diabetes and female sexual dysfunction correlate (Pontiroli. 2013) -- We already know that diabetes is a, if not the #1 risk factor for male sexual dysfunction, these days. Now a recent meta-analysis that's going to be published in one of the future issues of The Journal of Sexual Medicine found a 150% increase in sexual dysfunction in type II diabetes. Whether or not this was related to the higher depression rates in diabetic women cannot be said. What is certain, though, is that the BMI was a positive predictor of the effect size. In other words, the negative impact on sexual function increased with the degree of adiposity.
  
  Additional read for those women who feel it's their husband's performance that's to blame for their anorgasmia: "Pedalium murex Linn. fruits more effective than sildenafil in the long run and increases testosterone by 125%" (read more)
   

Now that's it for today, but I am now going out on a limb and promise another serving of short news with a focus on exercise early next week - something like the previous "Health & Exercise"- or the "Get Lean & Stay Lean" quickies and for once I can even tell you about one news that's definitely going to be in there - something about working out with and without breakfast.

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The obligatory reminder: In the mean time I'd suggest you devour the latest SuppVersity Facebook News @ www.facebook.com/SuppVersity. As usual they will receive a couple of updates way before the next official SuppVersity post is going to see the light of the day. Let's see, some of the most recent news are even remotely related to the On Short Notice items of today:

• Penis pumps - Scientists believe they are going to make a revival as a means of penile rehabilitation after surgery for prostate cancer (read more)
• Stress renders cancer immortal - What has just been observed in a rodent model of prostate cancer could have important implications for other cancers, as well (read more)
• PDE5 inhibitor for him, PDE-4 inhibitor for her? Study suggests: PDE-4 inhibitors could improve female sexual function (read more)
• Goose liver for the liver - When it's high in selenium goose liver could protect your liver from the assault of excessive alcohol consumption (read more)

As promised, there will be more. So in case you have not done so already,  you best like the SuppVersity right now so that the latest news will always appear in your news-feed.... ah, and about all that geeky science reading, don't forget that there is more to life than dieting and working out ;-)

References:

• Astbury NM, Taylor MA, Macdonald IA. Polydextrose results in a dose-dependent reduction in ad libitum energy intake at a subsequent test meal. Br J Nutr. 2013 Jan 23:1-9.
• Druesne-Pecollo N, Latino-Martel P, Norat T, Barrandon E, Bertrais S, Galan P, Hercberg S. Beta-carotene supplementation and cancer risk: a systematic review and metaanalysis of randomized controlled trials. Int J Cancer. 2010 Jul 1;127(1):172-84.
• Ehrlich HP, Hunt TK. Effects of cortisone and vitamin A on wound healing. Ann Surg. 1968 Mar;167(3):324-8.
• Gerber LE, Erdman JW Jr. Effect of dietary retinyl acetate, beta-carotene and retinoic acid on wound healing in rats. J Nutr. 1982 Aug;112(8):1555-64.
• Moraes-Silva IC, Mostarda CT, Moreira ED, Silva KA, Dos Santos F, De Angelis K, Farah VD, Irigoyen MC. Preventive role of exercise training in autonomic, hemodynamic and metabolic parameters in rats under high risk of metabolic syndrome development. J Appl Physiol. 2013 Jan 17.
• Pontiroli AE, Cortelazzi D, and Morabito A. Female Sexual Dysfunction and Diabetes: A Systematic Review and Meta-Analysis. J Sex Med. 2013 [e-pub ahead of print]

Polydextrose and Resistant Maltodextrin as Dieting Aids W/ GLP-1 Boosting & Appetite Reducing Effects: 7% Reduced Energy Intake per 10g/day of Polydextrose in Clinical Trials

Many of them look like powder sugar, but they are much more. Novel food ingredients like polydextrose or resistant maltodextrin may help us to slow the progression of obesity, but they won't solve the global obesity problems.

Whenever we are talking about resistant starches, we are not actually interested in the starches themselves, but rather in what happens after they are digested by the bacteria in our guts. The result of this process are short-chain fatty acids. These specific fatty acids interact with receptors in the digestive tract which in turn trigger the release of GLP-1, of which you as a SuppVersity reader have long known that it is of paramount importance for glucose and weight control (learn more).

Next to naturally occuring resistant starches in foods like cooled potatoes or green bananas and relative expensive high molecular weight designer starches, polydextrose and resistant maltodextrose constitute two promising food ingredients of which researchers believe that they may help us to keep the obesity epidemic at bay.

You can learn more about the gut & your health at the SuppVersity

Bugs Dictate What You Crave

Sweeteners & Your Gut

Foods, Not Ma- cros for the Gut

Lactulose For Gut & Health

Probiotics Don't Cut Body Fat

The Macrobiotic MaPi2.0 Diet

Resistant maltodextrin (RMD) is a water-soluble, non-viscous and non-digestible saccharide. Like polydextrose, resistant maltodextrin has previously been reported to improve the glycaemic response (12,13) and postprandial TAG elevation (14), and also promotes mineral absorption (15). The mechanisms involved in the improvement of glucose tolerance, however, are poorly understood.

Accordingly, the goal of Tohru Hira et al.'s latest study was to examine whether these effects that have been observed in both human and rodent studies, previously, could be mediated by changes in plasma GLP-1 levels and GLP-1 production in the small and large intestines.

Figure 1: Glucose levels after glucose load (A), changes in glucose (B) and total GLP-1 and active GLP-1 levels (C, D) with different amounts of resistant maltodextrin or fructo-oligosaccharides in the diet of the rodents (Hira. 2015).

If you've read the introductory paragraph of this article, you will not be surprised to see that the data from the Hokkaido University in Japan shows that the ingestion of resistant maltodextrin lead to dose-dependent (more = better) increases in GLP-1 in the blood (Figure 1, C-D) and the intestine (not shown), as well as corresponding improvements in glucose control (Figure 1, A-B).

Do not make the fatal mistake to believe that increasing your resistant starch intake alone will help you lose weight. Unless the increases in GLP-1 make you eat less food, you will -just like the rodents in the study at hand- not lose a single pound of body fat. In addition, polydextrose and probably also resistant maltodextrin - like many of the sugar replacements - has the nasty side effect of giving you the run if you consume high doses in isolation (Flood. 2004). So, if you want to use them, use them wisely.

In that, it is particularly important that the benefits the healthy rodents derived from the ingestion of resistant maltodextrin was significantly more pronounced than the benefits of fructo-oligosaccharides which have likewise been hailed as potential obesity preventers (Arora. 2013).

Speaking of obesity preventers,...

you are probably already wondering about the other "obesity preventer" I mentioned in the headline: Polydextrose, a a glucose polymer that is completely soluble in water and is used asa food additive to give foods the texture of sucrose at 75% lower calories in over 60 countries.

The effects and potential benefits this agent which is usually labeled as "fiber" on the label of commercially produced foods have recently been reviewed by scientists from the St Luke’s Roosevelt Hospital Center in New York (Ibarra. 2015). As of now, we know from several individual studies that polydextrose has the ability to reduce energy intake, but until now, no one had systematically reviewed the disparate evidence on this topic.

Figure 2: Calculated slopes of the effects of adding polydextrose to the diets of men and women on their food intake at lunch (left) and over 24h (right) - individual study results are represented as dots (Ibarra. 2015).

With the study by Ibarra et al. (2015) this review is now available and it shows significant effects on food intake at lunch (Figure 2, left) and total 24h food intake (Figure 2, right). Only the food intake at dinner was not significantly influenced in the few hitherto existing amply controlled clinical human trials (not shown in Figure 2).

A closer look at the data in Figure 2 does also show that there was - just like it was the case for the GLP-1 response to resistant maltodextrin ingestion in the Hira study - a dose-dependent increase in satiety with the ingestion of only 25g of polydextrose per day being able to reduce the total 24h food intake by more than 12%! Based on linear regression analysis the Ibarra et al. calculated the average decrease in food intake over 24h to be 3.8% and 2.3% per 10 gram of polydextrose consumed in men and women respectively. Significantly more pronounced effects were observed in studies investigating the effects of polydextrose ingestion at breakfast on food intake during an ad-libitum lunch which was reduced 7% and 5.7% per 10g in men and women.

According to the first meta-analysis of the existing human clinical trials consuming 10g of polydextrose per day leads will significantly decrease the food intake. The data does yet also show: Women benefit to a lesser degree than men.

Bottom line: There is little doubt that the consumption of increased amounts of resistant starches and more specifically GLP-1 boosting and appetite reducing resistant maltodextrin and polydextrose may help you to lose / control the amount of body fat you are carrying.

It is unrealistic, however, to assume that adding 20g of either of the agents to your diet would be sufficient to trigger significant fat loss in the absence of other lifestyle changes. It is furthermore interesting to observe that - once more - women appear to benefit less from the appetite reducing effects of these agent and that despite the fact that the relative contribution of 20g of these agents to the total food intake of a woman is lower than it would be for a man who obviously consumes more food | Comment on Facebook!

References:

• Arora, Tulika, Satvinder Singh, and Raj Kumar Sharma. "Probiotics: Interaction with gut microbiome and antiobesity potential." Nutrition 29.4 (2013): 591-596.
• Flood, M. T., M. H. Auerbach, and S. A. S. Craig. "A review of the clinical toleration studies of polydextrose in food." Food and chemical toxicology 42.9 (2004): 1531-1542.
• Hira, Tohru, et al. "Resistant maltodextrin promotes fasting glucagon-like peptide-1 secretion and production together with glucose tolerance in rats." British Journal of Nutrition (2015): 1-9.
• Ibarra, Alvin, et al. "Effects of polydextrose on different levels of energy intake. A systematic review and meta-analysis." Appetite 87 (2015): 30-37.