Different metabolic and absorption patterns of betaine in response to dietary intake of whole-wheat grain, wheat aleurone or rye aleurone in catheterized pigs

In the present study, a novel method of measuring the uptake of nutrients by 1H NMR spectroscopy was performed to determine dietary effects. Six pigs catheterized in the portal vein and mesenteric artery were fed breads made from whole-wheat grain (WWG), wheat aleurone flour (WAF; 19 % aleurone of bread) or rye aleurone flour (RAF; 15 % aleurone of bread) in a repeated 3 9 3 crossover design. Three meals were provided daily (at 0, 5 and 10 h), and each period comprised of 1 week. Portal and arterial blood samples were collected at fasting (-30 min) on day 4–7, and on day 7, pooled blood samples were collected at 0–2.5, 2.5–5, 5–7.5 and 7.5–10 h after first (0 h) daily meal. Using the arterial-venous difference and ANOVA–simultaneous component analysis, plasma betaine was found to accumulate during the experimental period. On day 7, plasma betaine concentrations was 20–40 % higher than when feeding the WAF diet compared with RAF and WWG (P = 0.001), whereas the content of betaine in the WAF diet was about twice as high. The arterial-venous difference showed a tendency (P = 0.078) for the diet–time interaction of betaine absorption in the absorption phases but there was no diet effect (P = 0.31), which indicates a steady-state absorption has been reached on day 7. Furthermore, high plasma betaine levels correlated with low plasma creatine of endogenous origin. In conclusion, the explorative method revealed that the plasma concentration and absorption of betaine were differentially modified by the diets.