Onions, soya, beans and pistachio nuts are all healthy, but endurance athletes are better off avoiding them in the week before a race, according to sports scientist David Nieman of Appalachian State University. These foods contain large amounts of the oligosaccharide raffinose [structural formula shown below] and, in an experiment involving 20 experienced cyclists, Nieman showed that raffinose reduces endurance performance.
Nieman gave 20 cyclists 85 g pistachio nuts daily and then got them to cycle 75 kilometres. On another occasion he repeated the procedure, but didn’t give the cyclists pistachio nuts.
The 85 g pistachio nuts provided the cyclists with 480 kilocalories. Pistachio nuts also contain high quantities of the oligosaccharide raffinose – which beneficial bowel bacteria like to feed on. The pistachio supplementation provided the cyclists with 5.3 times the normal amount of raffinose.
The pistachio nut supplementation reduced the cyclists’ speed by almost 5 percent over the 75 kilometres.
The cyclists’ blood contained more sucrose and more raffinose after they had consumed pistachio nuts. This is probably because the cyclists’ digestive system worked less well as a result of the intense physical exertion, and therefore substances that would not normally do so entered the blood.
The more raffinose there was in the blood, the more (12Z)-9,10-dihydroxyoctadec-12-enoate – or for short: 9,10-diHOME – the researchers detected. [Structural formula shown here.] 9,10-DiHOME is released when immune cells start to fight real or suspected intruders. The substance can induce cells to commit suicide, and reduces the activity of the cells’ mitochondria. Nieman thinks that 9,10-diHOME explains the reduction in performance that he observed in the cyclists.
Nieman suspects that his discovery will lead to a new way for endurance athletes to boost their performance: by reducing the amount of raffinose that they consume in the last week of pre-competition preparation. “If confirmed by other research groups, I believe a new sports nutrition policy will be developed that will recommend that athletes avoid foods containing raffinose in the days prior to endurance competition”, the researcher announced in a press release from his university. [appstate.edu November 19, 2014]
Nieman does not advise athletes to completely cut out foods that are high in raffinose. “Pistachio nuts, beans, oat bran and other foods that contain raffinose are extremely nutritious and essential to a healthy diet”, he says. “When athletes are training for intense competitions like long-distance cycling or marathons, this study suggests they should limit some of these raffinose-containing foods during the week prior to competition to maximize their overall performance.”
Influence of pistachios on performance and exercise-induced inflammation, oxidative stress, immune dysfunction, and metabolite shifts in cyclists: a randomized, crossover trial.
Pistachio nut ingestion (3 oz./d, two weeks) was tested for effects on exercise performance and 21-h post-exercise recovery from inflammation, oxidative stress, immune dysfunction, and metabolite shifts.
Using a randomized, crossover approach, cyclists (N = 19) engaged in two 75-km time trials after 2-weeks pistachio or no pistachio supplementation, with a 2-week washout period. Subjects came to the lab in an overnight fasted state, and ingested water only or 3 oz. pistachios with water before and during exercise. Blood samples were collected 45 min pre-exercise, and immediately post-, 1.5-h post-, and 21-h post-exercise, and analyzed for plasma cytokines, C-reactive protein (CRP), F2-isoprostanes (F2-IsoP), granulocyte phagocytosis (GPHAG) and oxidative burst activity (GOBA), and shifts in metabolites.
Performance time for the 75-km time trial was 4.8% slower under pistachio conditions (2.84 ± 0.11 and 2.71 ± 0.07 h, respectively, P = 0.034). Significant time effects were shown for plasma cytokines, CRP, F2-IsoP, GPHAG, and GOBA, with few group differences. Metabolomics analysis revealed 423 detectable compounds of known identity, with significant interaction effects for 19 metabolites, especially raffinose, (12Z)-9,10-Dihydroxyoctadec-12-enoate (9,10-DiHOME), and sucrose. Dietary intake of raffinose was 2.19 ± 0.15 and 0.35 ± 0.08 mg/d during the pistachio and no pistachio periods, and metabolomics revealed that colon raffinose and sucrose translocated to the circulation during exercise due to increased gut permeability. The post-exercise increase in plasma raffinose correlated significantly with 9,10-DiHOME and other oxidative stress metabolites.
In summary, 2-weeks pistachio nut ingestion was associated with reduced 75-km cycling time trial performance and increased post-exercise plasma levels of raffinose, sucrose, and metabolites related to leukotoxic effects and oxidative stress.
PMID: 25409020 PMCID: PMC4237504 DOI: 10.1371/journal.pone.0113725 [PubMed – indexed for MEDLINE]