Wednesday, April 10, 2013

True or False: Vinegar Reduces Postprandial Glycemia And Insulin Response. Vitamin D Must Be Taken With Fat or It Won't Work. Chewing Gum Will Help You Get & Stay Lean

This is quite an extraordinary Wednesday! To make sure that you don't have to go without your beloved Science Round Up, Carl and I are doing the show one day early, which means that you better make sure to make some room for listening to the show at 1PM EST (listen live!), if you want to be the first to learn the truth about the
    Is it possible that your significant other outpaces you on all cardio activities, because she has the hormonal edge?
  • effects of soy protein supplementation on the endocrine effects of exercise
  • psychological effects of performance enhancing drugs & supplements
  • interaction between dietary salt & your bodies ability to store magnesium
  • vitamin D "dosage equivalent" of two tanning bed sessions per week
  • estrogen's fat burning prowess
  • better (?) alternatives to testosterone gel
... and all the other great topics, you will be able to listen to after you've witnessed Alex aka Primalkid's premier (what an alliteration) as SuppVersity guest author. I suppose that most of you will already have noticed that he helps me more than just "a lot" by answering questions in the comment section. Oftentimes these are pretty individual things, but sometimes they are downright "True or False"-compatible - just as the mini-article on Vinegar, Alex sent me a couple of days ago.

Vinegar Helps Reduce Postprandial Glycemia and Insulin Spike

True (minimally edited answer written by Alex aka Primalkid) Recently, apple cider vinegar has earned merit as a health tonic. No longer sold solely as a condiment in grocery stores, more and more people see apple cider vinegar as a remedy. Its wide availability and affordability make it appealing to those who have browsed the Internet, read various diet books, or even read the label on the bottle, all of which make fame of its weight loss ability. But is there any truth about those "rumors" or do they belong to the same class of "repeat it until everyone believes it must be true" gems of dietary wisdom like the notion that "fat will reduce the insulin spike from a carby meal" (learn more about this one in the previous of "True or False")

The discussion following last week's installment of "True or False", particularly about the way generations of dieters have been fooled to believe that it was a good idea to drown your carbs in fat in order to minimize the insulin spike was probably the incentive for Alex to author his first (and maybe not last) SuppVersity article... well, a part of an article ;-)
A 2006 review of all relevant epidemiologic studies and clinical trials found that "many recent scientific investigations have documented that vinegar ingestion reduces the glucose response to a carbohydrate load in healthy adults and in individuals with diabetes" (Alex' emphasis in Johnston. 2006). The review also concluded that "vinegar ingestion increases short-term satiety."

A fairly recent randomized controlled trial seeking to investigate if a combination of cinnamon and vinegar would have an additive blood glucose-lowering or satiety-enhancing effect compared to the substances in isolation, however, "did not see an effect of acetic acid on blood glucose" (Mettler. 2009). The study consisted of 27 non-smokers 20 to 30 years old with normal BMI and fasting blood glucose. In other words, they may be considered healthy adults. The control meal consisted of 194g vanilla milk rice and 33g glucose dissolved in water, providing a total of 75g carbohydrates, 5g fats, and 7g protein, and was consumed after an overnight fast of at least ten hours.

The researchers concluded that "the most apparent difference between the studies was the food matrix with which the acetic acid or vinegar was ingested," and admit ignorance as to why the vinegar might work more or less in different contexts.
Table 1: Tabular overview of the design of the four trials in the 2010 study by Johnston et al.
Fortunately, the answer comes three months later when a group of researchers at The College of Nursing and Health Innovation sought to investigate the dosage, timing and application of vinegar for reducing postprandial glycemia (PPG) (Johnston. 2010). This study recruited both healthy and type-2 diabetic individuals, and had them consume either a meal (white bagel, 20g butter, 200g juice) or a glucose drink after a ten to 12 hour fast in four different trials.
  • Trial one examined whether small amounts (2 – 20g) of vinegar had any glycemic effects.
  • Trial two sought whether this effect persisted for five hours after consumption of the vinegar.
  • Trial three looked at whether the type of carbohydrate influenced vinegar’s antiglycemic effect.
  • Trial four looked at whether the neutralized salt of acetic acid was effective in diabetics.  
One detail I want to bring to your attention pertains trial 3 and could in fact explain why other studies failed to observe an antiglycemic effect of vinegar: In Mettler’s study, the control meal consisted of milk rice and a dextrose solution, both of which can safely be classified as "simple" sugars.

So, Johnston’s research suggests that the antiglycemic effect of vinegar is best realized when ingested with foods composed of complex carbohydrates and that vinegar may not attenuate PPG following the consumption of foods sweetened with corn syrups or dextrose, as is the case for many processed beverages and foods.

Bottom line: Aside from the fact that the last mentioned limitation implies that taking your vinegar with junk food is pointless, it appears that apple cider vinegar may in fact earn a place among the list of truly "functional" foods. And while the real-world benefits may be more pronounced for people who do already have slightly suboptimal (or worse ;-) insulin sensitivity, a small amounts of vinegar (2tsp - doesn't really matter which type) taken with a whole foods based meal may be considered one out of many proven dietary manipulations for reducing PPG. 

No Fat No Vitamin D - Fat's Necessary to Benefit from High Dose Vitamin D

Probably false. I know that you will now be citing an older post of mine discussing a study that showed quite conclusively that the usage of supplemental vitamin D is hampered, if it is not ingested with a significant amount of dietary fat (see "A Fat D-Ficiency").

Now, a soon-to-be-published paper by a group of scientists from the Human Nutrition Research Center on Aging at Tufts University and the Division of Endocrinology, Diabetes, and Metabolism at the Tufts Medical Center put a huge question mark after the results of the 2011 study by Raimundo et al. who had used an almost identical protocol in 20 likewise healthy subjects.
Figure 1: Changes in serum vitamin D3 and storage form of D3 (25OHD, small grey-scale graph) in response to 50,000 IU of vitamin D with / without a meal with high or low fat content (Dawson-Hughes. 2013)
As you can see in figure 1, the low fat meal did yield an even more rapid incline in plasma vitamin D3 levels, after the 90-day follow-up period the net "gain" in terms of serum 25OHD was yet identical in all three groups and brought the sixty-two 50-69 yrs subjects who were enrolled in this 3-month study well into the >70 nmol/L range for 25OHD - and that irrespective of whether they had ingested their D3 tablet** on empty or with an egg or egg white frittata with low or high amounts of olive oil and vegetables, turkey bacon, and Parmesan cheese topping, a slice of toast with either jelly (low-fat meal group) or butter, and a mango milk smoothie (mango, milk, ginger ale) with or without cream.
Foods & the Sun are the natural vitamin D sources, listen to today's Science Round Up to learn more about the latter.
** Note: I mentioned this before on the Science Round-Up: You better don't put too much faith into what the label of your D3 supplement says. Even with the supplement used in the study (50,000 IU vitamin D3 tablets that were purchased from BioTech Pharmacal) there was a >10% difference between what the label said the tabs would contain (obviously 50,000IU) and the measured amount of 57,000 IU of vitamin D3 the tabs actually contained. In the aforementioned study by Garg et al,. one of the tested vitamin D3 tabs contained more than twice of the labeled amount (Garg. 2013).
Just like Dawson-Hughes and colleagues, I can only speculate about the underlying reasons for the differences between the study at hand and the Raymundo study. The scientists' hypothesis that the unexpectedly high and early increase in the high fat (25.6g) group of the study by Raimundo et al. could be attributable to "inadvertent sun exposure or supplemental vitamin D ingestion in the second half of that study", would yet be a plausible explanation. Another one could be the use of cabs instead of tabs, as they were used in the study at hand. After all, the content of the 50,000IU vitamin D cap Raimundo et al. have used is like to be released much more rapidly so that the fat may have been necessary to slow the gastric emptying and thus facilitate absorption.

Bottom line: For you it does not really matter if you can ingest your vitamin D without fat. It's not the "better" alternative, so why would you bother anyway? So have it with a fatty meal, but don't forget that testing is not optional, but obligatory - I mean you do not even know how much vitamin D your Vitamin D product actually provides.

Chewing gum Helps to Get & Stay Lean (Note: This is just about regular chewing gum!)

True.  I know it may sound hilarious, but in view of the fact that research has shown "gum chewing is sufficiently exothermic that if a person chewed gum during waking hours and changed no other components of energy balance, a yearly loss of more than 5 kg of body fat might be anticipated." You can certainly argue that chewing of calorie-free gum, of which James Levin points out that it "can be readily carried out throughout the day", the "potential effect on energy balance should not be discounted" (Levin. 1999).
Mint chewing gums are incompatible to the "6x Bananas a Day!?" approach to lowering your glucose, insulin and HbA1c levels (learn more)
Chewing mint gums will reduce fruit consumption (Swobody. 2013) -- Why? Give it a try, I bet you will not recognize the delicious pineapple when you try to eat it right after you've been through a packet of Orbit Mint ;-) This may sound like it was not important, but it could in fact diminish or even blunt the effects of chewing gum... I mean think of Mr. Average Obese American at a barbecue. If he had not been chewing mint-flavored gum all the time, he may well have had his share of filling, refreshing & libido enhancing water melon before the barbecue was even ready to be served. Now that he missed on that, he will stick to the meat (+) and tons of salty junk (-). Not a good bargain, right?
Now, all of you know that I am no fan of the "calories in vs. calories out"-hypothesis Levin is referring to, here, but in view of the fact that chewing (sugar free!) gum has also been shown to
  • 8% reduced food intake on a "snack break" and generally reduced cravings and perceived likelihood of snacking on sweet foods in 40 women and 20 men (21.7+/-4 years; BMI=22.7+/-3.4) who participated in a 2007 study at the Glasgow Caledonian University) who came to the laboratory four times for lunch and then returned 3 h later for a snack after either chewing gum or not chewing gum for 15 minutes before the snack break (Hetherington. 2007). 
  • chewing gum will reduce the size of snacks even in moderately restraint eaters, although the effect is not as pronounced as it is in people who are not thinking about what and how much they are eating all day (Hetherington. 2011)
So, in general, it is probably advantageous to chew gum. The probability that it will result in significant weight loss is however small. A 2012 one of those pathetic randomized controlled trials, in the course of which the researchers provide their subjects with dietary advice and expect something to happen, the 102 of the 201 overweight and obese adults who were furthermore required to chew gum for at least 90min/day did not lose significantly more body weight or inches off their waist. Contrary to their non chewing gum chewing peers in the control group there was a greater heterogeneity so that only the difference to baseline reached statistical significance only in the chewing gum group.

If there is anything bad to say about chewing gums it would probably pertain to the (imho) not fully elucidated side effects xylitolm a proven "antimicrobial" (Mäkeläinen. 2007), could theoretically have on the gut microbiome, but since we do not know if that would be a detrimental and not even a beneficial effect (initial evidence exists, cf. Salminen. 1985), I just want to mention it as an "would be interesting to see more research in this direction". Possible artificial sweetener related distortions of the hedonic response to sweet foods, on the other hand, are not very likely... well, as long as you stick to the spearmint and peppermint varieties and refrain from those disgustingly sweet fruit gums.

There may be more advantages of chewing gum. People with GERD / reflux disease, for example have been shown to benefit from chewing gum for 1 h after the meal. The effect lasted for up to 3 h and occured in both patients with and without chronic reflux disease (Avidan. 2001). Chewing gum has also been shown to reduce the symptoms of depression (Erbay. 2013), alleviate acute psychological stress (Scholey. 2009), and increase alertness on "intellectual" performance during regular intelligence tests (Smith. 2009; similar effects in previous studies with sugar- and artificially sweetened gums, cf. Stephens. 2004)
Bottom line: The Shikany study is actually a perfect example of what chewing gum can do for the average dieter. Although it overall effects on caloric expenditure are non-significant the act of chewing and what my friend Carl Lanore once aptly called "cleaning one's pallet" with a sugar-free peppermint gum can help you (a) not to return to the buffet, once you've decided that you've had enough and started chewing gum and (b) not grab another snack between your main meals.

Against that background, the statement "chewing gum can help you lose weight" is actually correct. What is yet a hilariously unrealistic expectation is that you would - just like Levin mentioned it in the initially cited letter to the editor - be able to lose X pounds of pure body fat per year, because chewing gum increased the caloric expenditure of the subjects in the Levine study by 12kcal per hour.

That's what people in Germany call a "Milchmädchenrechnung" or as you would call it, my dear American friends, "naive fallacy" - a type of naive fallacy which is unfortunately still pretty common especially among people who make not one, but two major mistakes and don't read the SuppVersity and listen to Super Human Radio ;-)

That's it for the written part (don't miss the Science Round Up at 1PM EST, though!), I hope you enjoyed this installment of True or False and though I will be hard pressed to answer all the questions, just keep the suggestions coming. I will take the weekend to compile a detailed list to make sure I don't overlook any of them, when I tackle at least one of your suggestions in the future installments of this series.

  • Avidan B, Sonnenberg A, Schnell TG, Sontag SJ. Walking and chewing reduce postprandial acid reflux. Aliment Pharmacol Ther. 2001 Feb;15(2):151-5.
  • Dawson-Hughes B, Harris SS, Palermo NJ, Ceglia L, Rasmussen H. Meal conditions affect the absorption of supplemental vitamin D(3) but not the plasma 25-hydroxyvitamin D response to supplementation. J Bone Miner Res. 2013 Feb 20.
  • Erbay FM, Aydın N, Satı-Kırkan T. Chewing gum may be an effective complementary therapy in patients with mild to moderate depression. Appetite. 2013 Jun;65:31-4.
  • Garg S, Sabri D, Kanji J, Rakkar PS, Lee Y, Naidoo N, Svirskis D. Evaluation of vitamin D medicines and dietary supplements and the physicochemical analysis of selected formulations. J Nutr Health Aging. 2013 Feb;17(2):158-61.
  • Hetherington MM, Boyland E. Short-term effects of chewing gum on snack intake and appetite. Appetite. 2007 May;48(3):397-401.
  • Hetherington MM, Regan MF. Effects of chewing gum on short-term appetite regulation in moderately restrained eaters. Appetite. 2011 Oct;57(2):475-82.
  • Johnston CS, Steplewska I, Long CA, Harris LN, Ryals RH. Examination of the antiglycemic properties of vinegar in healthy adults. Ann Nutr Metab. 2010;56(1):74-9. 
  • Johnston CS, Gaas CA. Vinegar: medicinal uses and antiglycemic effect. MedGenMed. 2006 May 30;8(2):61.
  • Levine J, Baukol P, Pavlidis I. The energy expended in chewing gum. N Engl J Med. 1999 Dec 30;341(27):2100.
  • Mäkeläinen HS, Mäkivuokko HA, Salminen SJ, Rautonen NE, Ouwehand AC. The effects of polydextrose and xylitol on microbial community and activity in a 4-stage colon simulator. J Food Sci. 2007 Jun;72(5):M153-9. 
  • Mettler S, Schwarz I, Colombani PC. Additive postprandial blood glucose-attenuating and satiety-enhancing effect of cinnamon and acetic acid. Nutr Res. 2009 Oct;29(10):723-7. 
  • Salminen S, Salminen E, Koivistoinen P, Bridges J, Marks V. Gut microflora interactions with xylitol in the mouse, rat and man. Food Chem Toxicol. 1985 Nov;23(11):985-90.
  • Scholey A, Haskell C, Robertson B, Kennedy D, Milne A, Wetherell M. Chewing gum alleviates negative mood and reduces cortisol during acute laboratory psychological stress. Physiol Behav. 2009 Jun 22;97(3-4):304-12. 
  • Smith A. Effects of chewing gum on mood, learning, memory and performance of an intelligence test. Nutr Neurosci. 2009 Apr;12(2):81-8.
  • Shikany JM, Thomas AS, McCubrey RO, Beasley TM, Allison DB. Randomized controlled trial of chewing gum for weight loss. Obesity (Silver Spring). 2012 Mar;20(3):547-52.
  • Stephens R, Tunney RJ. How does chewing gum affect cognitive function? Reply to Scholey (2004). Appetite. 2004 Oct;43(2):217-8; discussion 221-3.
  • Swoboda C, Temple JL. Acute and chronic effects of gum chewing on food reinforcement and energy intake. Eat Behav. 2013 Apr;14(2):149-56.