Co-ingestion of protein and leucine with carbohydrate after activities of daily living improves whole-body protein balance, and the increase in muscle protein synthesis rates is not significantly different between lean young and elderly men.

The combined ingestion of carbohydrate with a protein hydrolysate and amino acid mixture significantly increases de novo insulin production in patients with a long-term diagnosis of type 2 diabetes. The increased insulin response stimulates plasma glucose disposal and reduces postprandial glucose concentrations.

This study examined postprandial plasma insulin and glucose responses after co-ingestion of an insulinotropic protein (Pro) hydrolysate with and without additional free leucine with a single bolus of carbohydrate (Cho). Male patients with long-standing Type 2 diabetes (n = 10) and healthy controls (n = 10) participated in 3 trials in which plasma glucose, insulin, and amino acid responses were determined after the ingestion of beverages of different composition (Cho: 0.7 g/kg carbohydrate, Cho+Pro: 0.7 g/kg carbohydrate with 0.3 g/kg protein hydrolysate, or Cho+Pro+Leu: 0.7 g/kg carbohydrate, 0.3 g/kg protein hydrolysate and 0.1 g/kg free leucine). Plasma insulin responses [expressed as area under the curve (AUC)] were 141 and 204% greater in patients with Type 2 diabetes and 66 and 221% greater in the controls in the Cho+Pro and Cho+Pro+Leu trials, respectively, compared with those in the Cho trial (P < 0.05). The concomitant plasma glucose responses were 15 and 12% lower in the patients with Type 2 diabetes and 92 and 97% lower in the control group in the Cho+Pro and Cho+Pro+Leu trials, respectively, compared with those in the Cho trial (P < 0.05). Plasma leucine concentrations correlated with the insulin response in all subjects (r = 0.43, P < 0.001). We conclude that co-ingestion of a protein hydrolysate with or without additional free leucine strongly augments the insulin response after ingestion of a single bolus of carbohydrate, thereby significantly reducing postprandial blood glucose excursions in patients with long-standing Type 2 diabetes.

The combined ingestion of carbohydrate with a protein hydrolysate and amino acid mixture significantly increases de novo insulin production in patients with a long-term diagnosis of type 2 diabetes. The increased insulin response stimulates plasma glucose disposal and reduces postprandial glucose concentrations.

Protein ingestion stimulates muscle protein synthesis and improves net muscle protein balance. Insulin resistance has been suggested to result in a reduced muscle protein synthetic response to food intake. As such, we hypothesized that type 2 diabetes patients have a impaired muscle protein synthetic response to food ingestion. To test this hypothesis, 10 male type 2 diabetes patients using their normal oral glucose-lowering medication (68 +/- 2 y) and 10 matched, normoglycemic men (65 +/- 2 y) were randomly assigned to 2 crossover treatments in which whole body and muscle protein synthesis were measured following the consumption of either carbohydrate (CHO) or carbohydrate with a protein hydrolysate (CHO+PRO). Primed, continuous infusions with L-[ring-13C6]phenylalanine and L-[ring-2H2]tyrosine were applied and blood and muscle samples were collected to assess whole-body protein balance and mixed muscle protein fractional synthetic rate over a 6-h period. Whole-body phenylalanine and tyrosine flux were higher after the CHO+PRO treatment compared with the CHO treatment in the diabetes and control group (P < 0.01). Protein balance was negative following CHO but positive following CHO+PRO treatment in both groups. Muscle protein synthesis rates were higher in both groups following the CHO+PRO (0.086 +/- 0.014%/h) treatment than in the CHO treatment (0.040 +/- 0.003%/h; P < 0.01) with no difference between the diabetes patients and normoglycemic controls. We conclude that the muscle protein synthetic response to CHO or CHO+PRO ingestion is not substantially impaired in longstanding, type 2 diabetes patients treated with oral blood glucose-lowering medication.

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The primary source of vitamin D is through synthesis in the skin, following exposure to sunlight containing ultraviolet B (UVB) radiation. Supply through skin exposure can be supplemented by the diet, but there are relatively few dietary sources, especially those which provide a large amount of vitamin D per serving. Research into the effects of vitamin D status in different population groups has become an increasingly popular topic. The current interest surrounding vitamin D research in sport remains focused on the potential ergogenic effects of vitamin D on physical performance. However, the relationship between vitamin D (dietary intake and status) and musculoskeletal health in university athlete cohorts residing at higher latitudes (>40°N) remains underinvestigated. Within this review, the possible physiological roles that vitamin D may play within sport performance for recreational and professional athletes, as well as military recruits, will be discussed. The focus will be on muscular strength, cardiovascular health and the incidence of illness, including upper respiratory tract infections. Specifically, the effect that vitamin D deficiency {defined as a plasma/serum 25‐hydroxyvitamin D [25(OH)D] concentration of <25 nmol/l} may have on musculoskeletal health, including the incidence of stress fractures, is discussed. The review also seeks to highlight avenues for future research within vitamin D and sport, in particular for populations residing at higher latitudes (>40°N) where wintertime vitamin D deficiency is prevalent. It is hoped that this review will help to raise the awareness of the importance of existing advice in the UK for the avoidance of vitamin D deficiency and international vitamin D guidelines (such as in the US) on the achievement of vitamin D sufficiency [serum 25(OH)D >50 nmol/l] for optimum health and performance in athletes, both professional and recreational.

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