Friday, March 23, 2012

Fructose Epimer D-Psicose Could Be First Sweetener to Actively Promote Weight Loss: Reduced Weight Gain and Direct Inhibitory Effect on Adipocyte Maturation in Rodent + Reduced Postprandial Glucose & Insulin in Human Trial

Image 1: No, just a few grams of d-psicose won't turn these into a "health food", but it could help ameliorate the "damage"
Good news for everyone with a sweet tooth! Right after stevia has finally made it to the European market, the next 1/2 natural sweetener is at the ready. It's called d-psicose and it is a cousin of fructose that is yet only 70% as sweet as sucrose (fructose is +20% sweeter than sugar) but has only 0.3% of its energy content. In other words on a per calorie base it is 233x sweeter than sugar. That alone would however hardly justify an individual blogpost. What is yet exciting about this molecule is that a recently published rodent study does suggest that it can inhibit adipocyte maturation and thusly exerts direct anti-obesity effects.

The first sweetener that will actively help in weight loss?

In the course of a 12-week trial, a group of Sprague-dawley rats was initially fed up with the standard laboratory "high fat diet" that is essentially an identical twin of the standard American diet with 15.1% of the energy from protein, 38.8% from fats and 47.1% from carbohydrates. After four weeks the rodents were assigned to different groups, which were either switched over to a standard diet (14.7% protein, 9.4% fat, 76.9% carbohydrates) or were maintained on the energy-dense high fat diet. Each of the study arms had another 5 sub-groups the animals in which received, either
  • normal (ND) or high fat (HF) diet without supplement (control),
  • ND or HF + 5% sucrose (SU-5),
  • ND or HF + 5% erythritol (ES-5),
  • ND or HF + 2.5% d-psicose (DP-2.5), or
  • ND or HF + 5% d-psicose (DP-5)
for another 52 days. The food intake and body weight of the animals was measured three times a week. At the end of the study, serum levels of total cholesterol (TC), triglycerides (TG), LDL-C and HDL-C were measured and biopsies were conducted to evaluate adipose tissue and liver weight.
Figure 1: Change in body weight, total food intake and feed efficiency (right axis) in the 2nd half of the study (data adapted from Chung. 2012)
As you can see in figure 1 there was a dose-dependent decrease in body weight gain, which left the rats in the HFD - ND-DP5 group, i.e. those animals who had been fattened up for 4 weeks and were then switched to a "normal" diet supplemented with 5% of d-psicose (with a food intake of ~20g per day, whit would be 1g per day, or in human terms ~ 0.3g/kg) at a final body weight level that was identical to the animals who had never been fat in the first place - and that despite a slightly higher food intake.

Could d-psicose be an ideal adjunct to your weight loss regimen?

In this context, it is important to note that the previously fattened rodents were already 23% "overweight". In other words, while the rodents on the normal diet kept gaining weight at a rate of 2.4-2.7g per day, the weight gain of the "fat" rodents in the ND-DP5 group was so profoundly ameliorated that they ended up at the same "normal" weight at the end of the study as the intially non-obese rodents on the standard diet. And even without the dietary switch, the addition of 5% d-psicose led to a profound (-50%) reduction in diet induced weight gain in the high fat group.
Figure 2: Total white adipose tissue (right axis, in g), epididymal, perirenal and retroperitoneal visceral fat (in g) in the different groups at the end of the post-fattening 52-day feeding period (data adapted from Chung. 2012)
And while the addition of the C-3 fructose epimer lead to a reduction in body fat in all animals, only the animals who had been switched to the high carb (=normal) diet, achieved body fat levels identical (2.5% d-psicose) and even below (5% d-psicose) those of the rats in the control group (cf. figure 2).

Lose weight, lose fat, but what about your liver?

Yet despite the fact the combined "weight loss effect" of the "normal" (=low fat) diet with supplemental d-psicose is thusly fundamentally different and unquestionably way more desirable than the "Half as Heavy, Twice as Fat" effect of the Atkins diet (cf. news from last Friday), the structural kinship of d-psicose and fructose raises the question if the former did induce similarly detrimental health effect on the liver as its notoriously sweet cousin.
Figure 3: Light image of liver tissue sections from ND, ND-SUS and ND-DP-5 groups (adapted from Chung. 2012)
The light image of liver tissue sections from the ND, the ND-SUS and the ND-DP-5 group does yet show that the dreaded NAFLD fatty deposition did not occur in the DP-5 group. The statistically significant increase in liver weight, on the other hand, is something the researchers attribute to increases in hepatic glycogen stores:
Our results [...] showed that ND-DP group tended to induce liver enlargement suggesting increased glycogen deposition in liver as extra-energy storage of d-psicose. However, HF-DP group did not show any difference compared to HF group. It is possible that HF diets containing relatively low carbohydrates [...] induced lower liver glycogen level masking the effects of d-psicose.
Moreover, previous long-term studies (12-18 months) by Yagi & Matsuo did not reveal any adverse side-effects in relation to the d-psicose induced increase in liver weight (Yagi. 2009).
Figure 4: Lipid profiles (triglycerides, LDL-C and HDL-C) at the end of the study period (data adapted from Chung. 2012)
The totally normal lipid profile (cf. figure 3), with lower triglyceride and cholesterol levels than the control group and identical total cholesterol to HDL-C (control: 1.73; DP5: 1.89) and LDL-C to HDL-C (control: 0.39; DP5: 0.39) ratios also supports the notion that, despite its "frutosian heritage", d-psicose is not promoter of diabesity and metabolic disease.

Bottom line: Promising, but more than one human study would be nice

Image 2: Sponge cakes made without addition, with fructose or with d-psicose (img courtesy of the Kagawa Industry Support Foundation)
If we add to that the results of a previous human trial, in which d-psicose administration reduced the postprandial glucose and insulin response following the ingestion of 75g of maltodextrin with 5g of d-psicose (Lida. 2008), and take into consideration that the incubation of pro-adipocytes with d-psicose led to a dose-dependent inhibition of adipocyte differentiation in the study at hand, the fructose epimer d-piscose could in fact turn out to be way more than just another artificial sweetener. And as you can see in image 2, the first practical applications, or should I say highly marketable "nutritional idiocies" are already on their way: Yummy sponge cakes ;-)