Abstract
Polyunsaturated fatty acid consumption has been shown to improve insulin sensitivity. We studied if administration of broth with beef meat enriched with polyunsaturated fatty acids influenced glucose-stimulated insulin release in healthy male volunteers. Broth was made either from cattles undergone dietary supplementation with lightly bruised whole linseed in addition to feeding ad libitum on grass silage (test meal) or from those fed grass silage alone (control meal). Oral glucose tolerance tests (OGTT) were performed in patients after a 6-day period of eating 300 ml broth containing 100 g meat once a day in addition to their otherwise normal mixed nourishment. During OGTT, blood samples were taken for blood glucose level and plasma insulin immunoreactivity before and 15, 30, 60, 90, 120, and 180 min after the glucose load. Glucose-stimulated maximum increase in plasma insulin immunoreactivity was 42 ± 6.6 and 81 ± 7.4 mU/ml (p < 0.05) after the test and the control meals, respectively. However, both fasting and postload blood glucose levels were the same after either meal period. The results suggest an insulin-sensitizing effect of food produced from beef cattle maintained on linseed diet in healthy human volunteers.
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Key Points
Studies on the effect of PUFA-rich food or PUFA-containing formulation on diabetes almost completely focus on fish oil. This study investigated the effect of meat derived from steers maintained on lightly bruised linseed-rich forage on glucose-stimulated insulin release in healthy male volunteers. In this pilot study, broth made from the meat of animals inhibited glucose-stimulated insulin release in young males at normal blood glucose level. This suggests that beef meat rich in linseed-derived fatty acids may be of beneficial influence on insulin sensitivity in human. The data presented here show that a daily intake of broth made from meat of animals maintained on lightly bruised linseed-rich forage, is able to inhibit glucose-stimulated insulin release in healthy male volunteers after as short period of broth exposure as 6 days. Feeding n−3 PUFA supplements as bruised linseed resulted in significant increases in their deposition in muscle lipids. Assuming that 100 g/d is an appropriate figure for beef consumption then it is feasible to calculate the contribution of n−3 fatty acids to the human diet. Consumption of 100 g/d of beef muscle from cattle fed on linseed, would provide a significant part of the appropriate intake of n−3 fatty acids. The study was carried out with young, healthy individuals; it is therefore difficult to extrapolate the results obtained to a population with either defined insulin resistance or type II diabetes with or without syndrome ischemic heart disease. Therefore, the present study sheds light on a currently less-defined target for functional food candidates of direct or indirect linseed origin being ingested in usual quantities at level of pancreatic beta cells.