New Results From the "Test Tubers": Paleolithic Men Could Have Been Healthier Had They Microwaved Their Potatoes.

Image 1: Potato roasting caveman-style - probably not the best way to "cook" your potatoes

As a non-native-speaker, I must admit that the first time I heard someone talk about "tubers" was on Robb Wolf's famous podcast, back in the day, when I was "listener #6" (or seven ;-). Contrary to common (foreign) belief, not all Germans subsist on potatoes and sauerkraut and, what's more, even those who do, don't really care that a potato is a "tuber", i.e. a "Knolle" in German - I suppose the idea that it grows in the dirt is not too appealing to some, while the large majority probably just doesn't care as long as those "tubers" make a good addition to their Schweinebraten... yet, whatever the reasons may be, my first encounter with "tubers" has ingrained the link of these "underground structure[s] consisting of a solid thickened portion or outgrowth of a stem or rhizome, of a more or less rounded form, and bearing ‘eyes’ or buds from which new plants may arise" (OED.com), as the venerable Oxford English Dictionary would have it, to the paleo style of eating so deeply into my brain that I have been seeing cavemen with roasted sweet potatoes on their sticks in front of a fireplace in my mind's eye, ever since. Now, if that really was the way life went, back in the paleolithic days, our ancestors did probably miss about 32% of the antioxidant magic of the tuberous roots - at least this is what the results of a recent study on the effects of different cooking methods on polyphenols, pigments, and antioxidant activity in potato tubers from the San Luis Research Center at the Colorado State University  would suggest (Perla. 2011).

In their experiment, Venu Perla, David G. Holm, and Sastry S. Jayanty

• boiled - 1h in a sieved double-boiler,
• microwaved + cooked - 10min in a commercial microwave oven at max. highest level +10min boiling, and
• baked  - 1h at 204°C in a commercial pre-heated oven

six months old stored potato tubers of 5 cultivars and 9 advanced selections of Colorado state (skin-color: 4x russet; 6x red; 1x white; 3x purple) and analyzed the samples for total phenolics, total flavonoids, total flavonols, and DPPH (2,2-Diphenyl-1-pikryl-hydrazyl) radical scavenging activity.

Figure 1: Loss in total polyphenol content of 5 cultivars and 9 advanced selections of Colorado state potato tubers due to cooking, microwaving, and baking (data calculated based on Perla. 2011).

As the data in figure 1 shows, all three preparation methods led to profound reductions of the potatos' total polyphenol counts. With Purple Majesty being most and Russet Nugget being least perceptible to the heat induced reduction in total polyphenol count. The cultivars CO97222-IR/R and CO97226-2R/R exhibited the highest total polyphenol counts (+77% and +137% above average in the raw state), with the former being particularly resistant to cooking (+119% above average) and the latter being particularly resistant to microwaving and baking (+154% and +169% above average, respectively).

Figure 1: Loss in polyphenol, flavenoid and flavenol content of 5 cultivars and 9 advanced selections of Colorado state potato tubers due to cooking, microwaving, and baking (data calculated based on Perla. 2011).

The superior resistance of these red-fleshed potato cultivars to cooking treatments is yet relative polyphenol-specific, due to their extraordinary high flavenoid and flavenol content in the raw state, CO97222-IR/R and CO97226-2R/R do yet retain a 241%, 155%, 199% and 243%, 331%, 395% higher flavenoid and 78%, 34%, 17% and 80%, 98%, 181% higher flavenol content  than the average potato (in the study) even after cooking, microwaving and baking, respectively.

The scientists also observed that, contrary to the white and yellow fleshed tubers, where the major pigment was lutein, the "dominant pigments in the red and purple fleshed tubers were anthocyanins", the antioxidant activity of which has been implicated in the prevention (by some even the treatment) of obesity, cardiovascular disease, diabetes, hyperlipidemia and even cancer. Unfortunately, these pigments are just as susceptible to cooking, microwaving and baking as the polyphenols, flavenoids and flavenols, so that the total anti-oxidant activity (as measured by DPPH free radical scavenging assays) of the tubers that were tested in this study was reduced by -26%, -32% and -38% by boiling, microwaving and baking, respectively.

Please note: While it is unlikely that you will die from eating a single raw potato. The solanine that can be found in all parts of the plant, including the leaves, fruit, and tubers, is a natural fungicide and pesticide the plant produces to protect itself from insects, the ingestion of which can potentially be fatal!

Now, despite the fact that microwaving is only slightly less damaging that baking, I assume that putting the potatos directly into the fire, like the paloelithic men and women in my daydreams use to do it, probably is the worst way to prepare your tubers. Yet while even microwaving would have been a healthier option, the best and, from an evolutionary perspective, more natural solution would be to boil your potatoes.

Passionate Diabesity Prevention: Passion Fruit Rind Extract Halves Weight Gain & Quadruples HDL on Regular Diet

Image 1: Looks like color matters! The yellow variety of Passiflora edulis is not just a particularly rich source of low-methoxyl pectin (dietary fiber), it's also packed with other bioactive substances which could keep you lean and healthy!

The title of the paper Sandra Maria Barbalho and colleagues published in the Journal of Diabetes Research & Clinical Metabolism a couple of days ago is quite telling "Yellow passion fruit rind (Passiflora edulis): an industrial waste or an adjuvant in the maintenance of glycemia and prevention of dyslipidemia?", as it does imply that we could once again have missed an important part of the whole picture in our never-ending strive for ever maximal standardization, isolation and convenience: The waste that is generated from Brazil's 35,000 hectare passion fruit industry, more than 317,000 metric tons of fiber-, mineral., vitamin-, phenol- and flavenoid-laden flavedo (colored part of the rind) and albedo (white part of the rind) from Passiflora edulis.

Passion Fruit Rind - Nothing in Nature is Wasted!

If we dig somewhat deeper into the archives of the medical, chemical and even historico-cultural journals, it's not as if we could not have known about the potential health benefits of the putative "natural packaging" that protects the juicy kernel of the fruits of a plant which belongs to the family Passifloracea and originated in the tropical and subtropical regions of the American continent. Previous studies by Deng, Janebro and Ramos, for example, did already hint at the potent anxiolytic, antihyperglycemic and antihyperlipedemic effects of a fruit that has a longstanding tradition in traditional medicine (Ramos. 2007; Janebro. 2008; Deng. 2010). Against that background, it is almost surprising that the existent literature on the use of respective extracts is not exactly comprehensive.

Figure 1: Changes in body weight (in g), absolute serum values (mg/mL) for glucose, triglycerides, cholesterol (total), HDL-C and LDL-C after 30 days of either regular or passion fruit bark powder solution (2x 1ml/kg body weight) supplemented diet in healthy Wistar rats (data adapted from Barbalho. 2012)

Malicious gossip would probably have it that the surprisingly profound effects Barbalho et al. observed in healthy rodents in response to the twice-daily administration of 1ml/kg bodyweight of a quasi-homemade (see infobox on the right of the next paragraph for details), obviously non-patentable passion fruit extracts would hamper the sales of metformin, lipitor and the recently FDA-approved weight loss drug Belviq (a 5-HTC-2 serotonin receptor antagonist). After all, aside from the decrease in LDL, all the diabetes- and  CVD relevant changes in figure 1 were statistically highly significant (p<0.01); and what's more, the necessary raw material is not just looked down upon, as if it was a waste product, it is according to the authors also treated like any other industrial waste by Brazil's passion fruit juice industry who either dumps it on illegal landfills or has to pay money for its proper disposal (Barbalho. 2012).

My GNC Does Not Have Passion Fruit Rind Extracts! Can I Make My Own?

How to home-brew your own PFR extract ;-)

1. dehydrate the rind on trays in a forced air circulation drying oven at 55ºC until a constant dry weight is reached
2. ground 200g into powder in a multiprocessor for 6 minute (turn off the processor at 2 min intervals to stir the product)
3. prepare a solution of 20 g of powdered rind and 500 mL of water
4. beat solution in a blender for 12min 
5. filtered through filter paper
6. divide resulting solution into aliquots and stored in a freezer at -10ºC

Ingest 2x10-14ml servings per day (standard HED calculation)

Ecology and health aside, I bet that for (too) many people the -76% reduction in weight gain would constitute the most convincing argument to buy Passion-o-Lean(TM) or whatever stupid name the first company whose "product designer" reads the study will come up with ;-)

Now, the good news is that we do actually have human data to confirm a statistically significant weight loss effect from passion fruit rind products: The nineteen 30-60 year-old, still normal-weight (BMI 24.8kg/m²) but hyperlipidemic (cholesterol > 200 mg/dL; went down by -18% as a result of supplementation) women in the aforementioned study by Ramos et al. lost 1.7 kg within one month (Ramos. 2007), but they did ingest 30g of passion flower rind flour per day and the weight loss stalled in the second month in the course of which they lost <300g, only - by no means as impressive as the weight loss, or, I should say, the absence of weight gain in the rodents from Barbalho study, right?

Due to the fact that Ramos et al. don't disclose how the co-authoer Sabaasrur, who provided the flour, actually prepared it, we cannot definitely answer the question whether or not these differences could simply be a result of the different preparation methods and consequent yield of bioactive substances in the extract (Barbalho. 2012) and the flour (Ramos. 2007). It is however very unlikely that the production of the floor involved either low temperature drying (1), water extraction (3-5) or refrigeration to maintain the maximal vitamin and phenols content (see figure 2) as they were part of the manual extraction process that was used in the Barbalho study (for details on the preparation see box on the left).

Figure 2: If you are more of a juicer, make sure to drink your juice right away to get the maximum amount of the good phenolic acids and avoid the potentially hazardous HMF (click to enlarge for more info; data based on Talcott. 2003)

Implications: Despite the fact that the data in figure 2, though based on an analysis of passion fruit juice, would support the hypothesis that the handmade passion fruit rind extract in the Barbalho study was more than just one magnitude "stronger" than the flour that's been used with some success in the Ramos and the Janebro study, it is still questionable, whether the profound reductions in blood glucose, the  improvements in the triglyceride (1.3 vs. 4.3) and total cholesterol to HDL ratios (2.5 vs. 10.4) will translate 1:1, or even at all to human beings. After all, it could be partly mediated by the reduced weight gain... apropos, 'not gaining weight' is still very different from 'losing weight' and it is therefore not feasible to compare, the relatively mediocre weight loss in the Ramos study, of which the scientists assume that it was, just as the reduction in cholesterol, mediated by the high content of soluble fiber in the passion fruit flour (73% of the dry matter is fiber, 60% of it insoluble; Yapo. 2008), to the profound 'anti-obesity' effect in the Barbalho study.

Moreover, in the absence of detailed information about the body composition of the lab animals and their energy intake, we could as well be dealing with the results of micronutrient malabsorption or anorexia as root causes of the reduced body weight in the passion fruit rind extract group of the Barbalho study.... although, with the twice daily bolus administration of only 2x 1ml of the PFR extract, both explanations, i.e. 'failure to thrive due to nutrient malabsorption' and 'anorexia in response to too much fiber', appear pretty unlikely, so that passion fruit rind extract would actually be a good candidate for a home-brew diabesity prevention potion... well, at least if you live next to one of those Brazilian dumping grounds where the passion fruit industry disposes of their hitherto unrecognized treasures ;-)

References:

• Barbalho SA, da Silva Soares de Souza M, de Paula e Silva J, Mendes CG, de Oliveira GA, Costa T, Farinazzi-Machado. Yellow passion fruit rind (Passiflora edulis): an industrial waste or an
  adjuvant in the maintenance of glycemia and prevention of dyslipidemia? FMV. Journal of Diabetes Research and Clinical Metabolism. 2012.
• Deng J, Zhou Y, Bai M, Li H, Li L: Anxiolytic and sedative activities of  Passiflora edulis f. flavicarpa. J Ethnopharmacol  2010; 128;(1.);148-53.
• Janebro D I, Queiroz M S R, Ramos A T, Sabaa-Srur A U O, Cunha MAL,  Diniz M F. Effect of the flour of the yellow passion fruit peel (Passiflora  edulis f. flavicarpa Deg.) in the glycemic and lipid levels of type 2 diabe- tes patients. Rev Bras Farmacog 2008;18: 723-732. 
• Ramos AT, Cunha MAL, Sabaasrur AUO, Pires VCF, Cardoso AA et al. Use of Passiflora edulis f. flavicarpa on cholesterol reduction. Braz J Pharmacog 2007;17: 592-560.
• Talcott ST, Percival SS, Pittet-Moore J, Celoria C. Phytochemical composition and antioxidant stability of fortified yellow passion fruit (Passiflora edulis). J Agric Food Chem. 2003 Feb 12;51(4):935-41.
• Yapo BM, Koffi KL: Dietary fiber components in yellow passion fruit rind - a potential fiber source. J Agric Food Chem  2008; 56;(14.);5880-3. 

Three Servings of Grapefruit /Day Have No Effect on Weight Loss, But Increase Triglycerides and Make a Potentially Deadly Cocktail With A Whole Host of Prescription Meds!

Image 1: Grapefruit does not help with weight loss and, as it turns out, is not even healthy. On the contrary, in conjunction with your favorite statin it is even potentially deadly.

Do you remember the "grapefruit diet" (WebMD)? No? Well, then you are probably male and have always been satisfied with your weight. Otherwise, you would probably have heard how a "magical ingredient" in the subtropical citrus fruit is going kill all those unaesthetic adypocytes, which have made themselves at home on your hips and buttocks, in no time... What do you say? Bullsh*t? Well, I guess you have been reading to much of my stuff already, after all this purported short-cut to six-pack abs is also known as the Hollywood Diet and that alone will have people fall for it by the dozen... I mean, if Brooke Shields and Kylie Minogue got in shape with it, it must be working, right?

The myth and the truth about grapefruits

I know that you would never be so stupid to start eating nothing but grapefruit (you would not, right?), but despite the fact that the Grapefruit Diet has rightly gotten a bad rep within the (self-)educated members and followers of the wealth of good and not-so-good blogs and websites dealing with nutrition and weight loss, many people still believe that there must be something about this fruit that will help you lose weight. And in view of the fact that I myself know a couple of these (interestingly all female) unfortunate critters, I believe that it is still worth to take a closer look at the results of a recently published study on the effects of 1.5 fresh Rio-Red grapefruit per day on the outcomes of a 6-week dietary intervention (Dow. 2012). The study involved 74 male and female subjects (age: 41y; BMI: 32kg/m²; Bodyfat: 35.7%) who, despite having problems with their weight, had been weight-stable in the past 6 months (or more). After an initial 3-week "wash out period" in the course of which the subjects had to follow a diet that was restricted in bioactive-rich fruits and vegetables (the intention, here, was to get all to a baseline level as far as the purported "magic fat loss ingredient" in citrus fruits is concerned), the subjects were randomized to one of two groups:

1. intervention group (n=42) continued eating the "wash-out diet" and supplemented with their 3x0.5 Rio-Red grapefruit per day 15 minutes prior to their regular three meals
    
2. control group (n=32) continued eating the "wash-out diet"

The dietary intake of the subjects, was evaluated with your usual (unreliable, but in want of alternatives obligatory) repeated 24-hour diet recalls (3x during the washout phase and 3x during the intervention phase). Things like the total caloric intake (1800-1900kcal) or the macronutrient composition did not really differ between diets - in other words: The scientists did a pretty good job to isolate the grapefruit intake and the (obviously) correlating vitamin C intake (cf. figure 1) as the single confounding factors in their study.

Figure 1: Total caloric intake, the number of vegetable servings, the overall macronutrient ratio etc. all were identical between the two groups, except the fruit and (consequently) the vitamin C intake (data based on Dow. 2012)

With a subject pool of 74 men and women and virtually identical diets, we should thusly well be able to see an effect on body weight, body fat, lipid or glucose metablism, if there was one, but as the data in figure 2 indicates, "the magic just did not happen":

Figure 2: Relative changes in anthropometric data in the course of the 6-week study period; no statistically significant inter-group differences, not even statistical significant pre-post changes (data based on Dow. 2012)

Aside from the fact that grapefruit does not make you lose fat, the graph in figure 2 carries another important message, which is: Never use a body impedance device to track your progress. And this goes for all those stupid things, and not only the Omron Body Fat Analyzer HBF-306 which was used in the study. Why? Well, take a look at the body fat and the waist circumference data: How can your gut become smaller, when your body fat percentage increases? The answer is easy, because the grapefruit eaters lost water, they lost ~1% more of their waist circumference. This did yet change the impedance of their bodies so that the stupid for the Omron was tricked to believe that the body fat percentage of the study participants had increased (if you are at a loss how you can track your progress, make sure you read the Intermittent Thoughts on "Stocktaking, Goalsetting, -Tracking & -Resetting").

"But, Dr. Andro, weight loss is not everything" - Correct! And another reason not to eat huge amounts of grapefruits

Another argument of the "grapefruit fanatics" is that, although the weight loss effects of the fruit may be negligible, it still is a healthy superfood that will improve your overall and metabolic health... now, if we take a look at what (unfortunately) is still considered the "gold-standard" as far as the assessment of CVD risk is concerned, i.e. the allmighty lipid profile (imagine a fanfare, here), I guess that only those of you who still believe in the black-and-white version of the lipid hypothesis (HDL = good guy; LDL = bad guy; nothing else counts) will wholeheartedly agree with Dow et al. conclusion that ...

grapefruit consumption does elicit beneficial effects compared with baseline values that are
associated with CVD risk reduction.

If you take a look at the actual data in figure 3 you can hardly argue that the 1.5 grapefruits à day gave the "bad guy" (LDL) a slightly more thorough beating than the "wash out diet" with its quasi non-existent polyphenol content, but...

Figure 3: Changes in lipid profile (unadjusted and adjusted with ANCOVA for BMI, age, sex, and washout-phase p-values) for the control and grapefruit group (left) and the questionable conclusion the scientists draw based on the observed reduction in LDL and statistically likewise non-significantly greater reductions in blood pressure in the grapefruit group (right) (based on Dow. 2012)

...with a p-value (indicating the probability that this is mere coincidence; p < 0.05 is considered "statistically significant) of p = 0.871 for the inter-group difference this difference did not only fail to reach statistical significance, it must also be seen in the context of an increase in triglyceride levels (instead of a decrease in the control group), of which a 2009 study by Kannel et al. states that

[...n]onfasting triglycerides maintained an independent graded relationship with CVD in fully adjusted analyses, with elevated 4 h postprandial triglyceride imposing a 4.5-fold increment relative to lower levels [...and that] triglyceride-associated CVD risk occurs even in patients with low low-density lipoprotein cholesterol (Kannel. 2009)

Just to make sure nobody is missing the point here, neither the inter-group differences in LDL reduction nor the different outcomes as far as the trigs are concerned, reached statistical significance, but against the background of the results of the meta-analysis of Kannel and Vasan from 2009 and recent findings on the contribution of elevated triglyceride levels to the etiology of cardiovascular and metabolic diseases, I personally feel that beyond not helping with weight / fat loss, eating grapefruit could potentially even contribute to, or aggravate existing metabolic disturbances.

If you are on any medication grapefruit is a no-go, anyway!

Image 2: If you are healthy eating grapefruits from time to time won't hurt. If you are taking medication, however, it can potentially be fatal - although I's say that the meds, not the fruit are to blame for this

Yet even if you don't care about the pro-diabetic effects of triglycerides and discard the non-existent effect of grapefruits on weight loss / body composition, there is another, probably more important, because potentially fatal side-effects of eating grapefruit (or drinking its juice / taking respective supplements), which relates to the inhibitory effects it exerts on a hitherto not fully elucidated number of liver enzymes in the cytochrome cascade (CYP), which is heavily involved in drug and hormone metabolism. So, even if you don't take a statin, of which Dreier et al. have shown that it can induce profound rhabdamyolysis (=total break down of muscle protein, which can lead to kidney failure and death), when the grapfruit flavenoids and polyphenols block its metabolism in the liver (Dreier. 2004), or any other of the countless drugs the effects of which are profoundly modulated by the ingestion of grapfruit or grapefruit juice (Hanley. 2011), you better stick to no more than a single grape-fruit once in a while... I mean, it has no beneficial health / weight loss effect, anyway.