Chronic oral ascorbic acid therapy worsens skeletal muscle metabolism in patients with chronic heart failure.

BACKGROUND: Chronic heart failure (CHF) is associated with abnormalities of skeletal muscle metabolism. This may be due to impaired oxygen delivery as a result of endothelial dysfunction. AIMS: We postulated that ascorbic acid would improve oxygen delivery to exercising muscle and improve skeletal muscle metabolism. METHODS: We studied skeletal muscle metabolism using (31)P magnetic resonance spectroscopy in 39 CHF patients. Endothelial function was assessed by changes in pulse wave velocity. Subjects were randomised to receive 4 g ascorbic acid daily for 4 weeks in a placebo-controlled double-blind study. RESULTS: Ascorbic acid significantly increased phosphocreatine utilization during exercise. In addition, glycolytic ATP synthesis increased in the ascorbic acid group (change in rate of ATP synthesis at 1 min -0.21+/-0.76 with placebo, 2.06+/-0.60 following ascorbic acid; p<0.05). Phosphocreatine and ADP recovery after exercise were not changed. The fall in pulse wave velocity during reactive hyperaemia was increased by ascorbic acid from -6.3+/-2.6% to -12.1+/-2.0% (p<0.05). CONCLUSIONS: These findings suggest that ascorbic acid increased both phosphocreatine utilization and glycolytic ATP synthesis during exercise in patients with CHF implying worsened skeletal muscle metabolism despite improvements in endothelial function.

UK Food Standards Agency alpha-linolenic acid workshop report.

The UK Food Standards Agency convened a group of expert scientists to review current research investigating whether n-3 polyunsaturated fatty acids (PUFA) from plant oils (alpha-linolenic acid; ALA) were as beneficial to cardiovascular health as the n-3 PUFA from the marine oils, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The workshop also aimed to establish priorities for future research. Dietary intake of ALA has been associated with a beneficial effect on CHD; however, the results from studies investigating the effects of ALA supplementation on CHD risk factors have proved equivocal. The studies presented as part of the present workshop suggested little, if any, benefit of ALA, relative to linoleic acid, on risk factors for cardiovascular disease; the effects observed with fish-oil supplementation were not replicated by ALA supplementation. There is a need, therefore, to first prove the efficacy of ALA supplementation on cardiovascular disease, before further investigating effects on cardiovascular risk factors. The workshop considered that a beneficial effect of ALA on the secondary prevention of CHD still needed to be established, and there was no reason to look further at existing CHD risk factors in relation to ALA supplementation. The workshop also highlighted the possibility of feeding livestock ALA-rich oils to provide a means of increasing the dietary intake in human consumers of EPA and DHA.