|Lactobacilli are hip, vitamin A is not - at the SuppVersity you still get news on both|
Before we take a closer look at a definite benefit of having the "right" gut bacteria, though, let's start out with another likewise gut-related news item on the role of retinoic acid in T-cell education. In a way it's funny, it starts right where the bacteria reside, could have immune-modulatory effects that are way more pronounced and far reaching than probiotics and is still hardly discussed.
Vitamin A is of critical importance to (intestinal) T-cell educationIf you have ever asked yourself how the immune cells in your body know what they are supposed to do, Catharine Ross' latest paper that was published in the American Journal of Clinical Nutrition and is based on a short talk the researcher from the Department of Nutritional Sciences at the Pennsylvania State University held at a conference earlier this year may provide at least some additional insides into the role a still way underrated molecule plays in this "T cell education" (Ross. 2012): Vitamin A!
|Figure 1: Model of T cell differentiation, from uncommitted naive T cells into different T cell subsets that produce different cytokines and thus promote different functional activities (adapted from Ross. 2012)|
"[...] in a state of vitamin A deﬁciency, inﬂammatory T cell reactions may be inadequately opposed and therefore become dominant [...] Although data from human studies are still needed, the framework now developed from studies in mice and rat models suggests that adequate vitamin A status, [...] is important for maintaining a proper balance of well-regulated T cell functions and for preventing excessive or prolonged inﬂammatory reactions." (Ross. 2012).
|Discovery a beta carotene derived vitamin A receptor blocker is only one of a couple of intriguing findings wrt to vitamin A.|
"RA is essential for 'imprinting' gut-homing speciﬁcity on T cells activated by intestinal DCs [dendritic cells] and suggested that MLN DCs are a source of RA that drives T cell differentiation toward the gut-homing phenotype" (Ross. 2012)Moreover, oral tolerance to foreign antigens and thus an allergy free live requires a form of immune suppression, which can be proffered or hampered by sufficient and insufficient vitamin A intakes. In that, the exact effects of vitamin A will depend on the cytokine milieu the T-cells are exposed to. Examples are...
- an exaggerated IL-17 response with vitamin A deficiency, on the one hand, and
- an increase of the inflammatory response due to high vitamin A in an IL-15 environment
Combination therapy with vitamin A and a vitamin D (not D3, but calcitriol) analog EB1089 kills liver cancer cells. And it does so more effectively than any of the two molecules alone. That's the actually unsurprising result of a study that has been conducted at the Beijing Army General Hospital in China. The researchers injected nude mice with molecules that made them develop hepatocellular cancer. Afterwards, the rodents received either 10 μmol/L retinoic acid (vitamin A), 10 nmol/L EB1089 or both as a combination treatment.
Figure 2: Who cares about cell viability, the survival time (in days) matters
Compared to vitamin A or the calcitriol analog alone, the combination treatmend resulted in a significanlty higher reduction of the viability of hepatocellular cancer cells. Based on TUNEL analysis, Zhang et al. did also establish that individual cancer cells had a higher apoptotic ratio in the combined drug group than in the groups for which the drugs were used separately. Most importantly, however, the tumor weight was decreased and the mice on the combination treatment lived significantly longer (see figure 2; Zhang. 2012)
Skimmed milk, the ideal post-workout rehydration formula? According to L James' paper in Lamprecht's compendium Acute Topics in Sport Nutrition, milk is a way better choice then the standard sugar + electrolyte rehydration formulas. Interestingly this is not due to the minerals in the milk, or the sugar, but, as James argues, a direct consequence of the milk proteins, which help restore "fluid balance after exercise-induced dehydration to a greater extent than a carbohydrate-electrolyte sports drink." As James points out it will yet have to be elucidated, whether the simple addition of whey protein to a standard sugar + electrolyte formula would exert similar effects (James. 2013).
In the same publication, Pritchett and Pritchett recommend 1.0-1.5ml / kg body weight per hour of chocolate milk as the optimal post-workout drink to be consumed in the 2 h after a workout.
- Probiotics to kill Helicobacter Pylori? While not every bacteria stands a chance against the nasty gut bug H. Pylori, certain Lactobacillus spp. strains obviously do. At least, if the results of a recent in-vitro + in vivo rodent study by Pei-Shan Hsieh can be replicated in human studies.
Lactobacillus acidophilus TYCA08, L. acidophilus TYCA15, L. johnsonii MH-68, and L. salivarius subsp. salicinius AP-32 were the most effective strains the researchers from National Chung Hsing University in Taichung, Taiwan, analyzed. And believe it or not, the latter of these, i.e. L. johnsonii MH-68, and L. salivarius subsp. salicinius AP-32, both of which are by the way found in feces, were even minimally more potent effective than Amoxicillin, a moderate-spectrum, bacteriolytic, β-lactam antibiotic used to treat bacterial infections. L. acidophilus TYCA15, however, steals the show. This probiotic that occurs naturally in breast milk reduced the urease activity of H. Pylori by -97.1% (see figure 3).
Figure 3: Urease activity in H. pylpori after co-incubation with the specific probiotic and resulting bacteriostatic ratio (100% = bacteria free; data adapted from Hsieh. 2012)
In the consecutive rodent study, Hseieh et al. did yet still use 109 CFU/mL of either AP-32 alone, MH-68 alone, or an equal mix of cultures of the two strains and both, "either alone or as a mixture in powder form were effective in reducing H. pylori load in gastric mucosa and help in reducing gastric inflammation and in regulation of gastric acid production." (Hsieh. 2012)
- Beaton GH, Martorell R, Aronson KA, Edmonston B. McCabe, G, Ross, AC, Harvey, B. Vitamin A supplementation and child morbidity and mortality in developing countries. Food Nutr Bull 1994;15(4): 282–9.
- Blaut M, Klaus S. Intestinal microbiota and obesity. Handb Exp Pharmacol. 2012;(209):251-73.
- Hsieh PS, Tsai YC, Chen YC, Teh SF, Ou CM, King VA. Eradication of Helicobacter pylori Infection by the Probiotic Strains Lactobacillus johnsonii MH-68 and L. salivarius ssp. salicinius AP-32. Helicobacter. 2012 Dec;17(6):466-77.
- James L. Milk Protein and the Restoration of Fluid Balance after Exercise. In Lamprecht M (ed): Acute Topics in Sport Nutrition. Med Sport Sci. Basel, Karger, 2013, vol 59, pp 120–126.
- Pritchett K, Pritchett R. Chocolate Milk: A Post-Exercise Recovery Beverage for Endurance Sports. In Lamprecht M (ed): Acute Topics in Sport Nutrition. Med Sport Sci. Basel, Karger, 2013, vol 59, pp 127–134.
- Ramgolam VS, Markovic-Plese S. Interferon-beta inhibits Th17 cell differentiation in patients with multiple sclerosis. Endocr Metab Immune Disord Drug Targets. 2010 Jun;10(2):161-7.
- Ross AC. Vitamin A and retinoic acid in T cell-related immunity. Am J Clin Nutr. 2012 Oct 10.
- Schambach F, Schupp M, Lazar MA, Reiner SL. Activation of retinoic acid receptor-alpha favours regulatory T cell induction at the expense of IL-17-secreting T helper cell differentiation. Eur J Immunol. 2007 Sep;37(9):2396-9.
- Zhang J, Zhang H, Zhang X, Yu Z. Synergistic effect of retinoic acid and vitamin D analog EB1089-induced apoptosis of hepatocellular cancer cells. Cytotechnology. 2012 Oct 16.