Metabolic effects of non-absorbable carbohydrates

Perspective: Public Health Nutrition Policies Should Focus on Healthy Eating, Not on Calorie Counting, Even to Decrease Obesity

Calorie-focused policies, such as calorie menu labeling, seem to result in minor shifts toward healthier choices and public health improvement. This paper discusses the (lack of) relations between energy intake and healthy eating and the rationale for shifting the focus of public health nutrition policies to healthier foods and meals. We argue that the benefits of reducing caloric intake from low-quality foods might not result from the calorie reduction but rather from the reduced consumption of low-quality foods. It is better to consume a given number of calories from high-quality foods than a smaller number of calories from low-quality foods. It is not possible to choose a healthy diet solely based on the caloric value of foods because calories are not equal; they differ in nutritional quality according to their source. Foods are more than just a collection of calories and nutrients, and nutrients interact differently when presented as foods. Different subtypes of a macronutrient, although they have the same caloric value, are metabolized and influence health in different ways. For instance, industrial trans fats increase lipogenesis and the risk of heart diseases, whereas monounsaturated fats have the opposite effect. Food processing and cooking methods also influence the nutritional value of foods. Thus, public health nutrition policies should stop encouraging people to focus mainly on calorie counting to fight noncommunicable diseases. Instead, policies should focus on ingredients, dietary sources, and food processing and cooking methods.

Diurnal postprandial responses to low and high glycaemic index mixed meals

BACKGROUND & AIMS

Glycaemic index testing is conducted in the morning, however postprandial glycaemia has a diurnal rhythm. The study aimed to evaluate the effect of glycaemic index on glucose tolerance at different times during the day.

METHODS

A randomised controlled crossover study was conducted in ten healthy participants after a standardised premeal and eight hour fast. Low (37) and high glycaemic index (73) meals, matched for energy, available carbohydrate, protein and fat, were consumed at 08:00 h and 20:00 h. Blood samples were taken for 2 h postprandially.

RESULTS

Postprandial glucose area under curve showed effect with time of day after both meals (Low p < 0.001, High p = 0.003), and a trend (p = 0.06) to higher glycaemic responses in the evening for low glycaemic index meal. No differences were observed in insulin responses. Despite the calculated difference in meal glycaemic index little difference was observed in morning responses, but differences were seen in the evening when insulin insensitivity is increasing, the glycaemic response increase was proportionally greater for low glycaemic index meals.

CONCLUSIONS

Low glycaemic index foods are of less value in glycaemic control in the evening than the morning. Consuming food late in the day has a detrimental metabolic impact irrespective of glycaemic index.

The effectiveness of glucose, sucrose, and fructose in treating hypoglycemia in children with type 1 diabetes

OBJECTIVE

There is a lack of evidence regarding the most effective treatment option for managing naturally occurring hypoglycemia in children with type 1 diabetes. The objectives of this study were (i) to determine if sucrose and fructose are equally effective as glucose in the treatment of spontaneous hypoglycemia in children with type 1 diabetes; and (ii) to determine prestudy and poststudy hypoglycemia treatment preferences.

METHODS

Thirty-three subjects [aged 5.4-15.5 yr and average duration of type 1 diabetes of 3.1 yr (SD = 2.3)] participated in a randomized, crossover design. The main outcome was the effectiveness of treatment as defined by a blood glucose meter reading that was > or = 4.0 mmol/L 15 min after treatment. Each subject treated five hypoglycemic events with each treatment type: glucose (BD Glucose Tablets), sucrose (Skittles), and fructose (Fruit to Go).

RESULTS

There was a significant difference between the effectiveness of the three treatments [Wilk's Lambda F(2,28) = 8.64, p = 0.001]. No significant difference between treatment with glucose and treatment with sucrose was noted, but the treatment effectiveness for fructose was significantly lower than sucrose [F (1,29) = 16.09, p < 0.001] and glucose [F (1,29) = 15.64, p < 0.001]. The preferred treatment choices before the study were as follows: 36% glucose, 18% sucrose, and 33% fructose sources. Poststudy, 52% of children preferred the same treatment, which was effective (glucose or sucrose), followed by 35% who changed their preference to an effective treatment.

CONCLUSION

Skittles are as effective in treating hypoglycemia as more expensive BD Glucose Tablets in children with type 1 diabetes.

L-rhamnose and lactulose decrease serum triacylglycerols and their rates of synthesis, but do not affect serum cholesterol concentrations in men

Colonic short-chain fatty acids (SCFA) may affect hepatic lipid metabolism. Lactulose increases colonic acetate production, whereas L-rhamnose increases propionate. To test the effects of oral L-rhamnose and lactulose for 28 d on fasting concentrations and hepatic synthesis of lipids in humans, 18 men were administered 25 g/d of L-rhamnose, lactulose, or d-glucose for 4 wk in a partially randomized crossover design, with blood collected from fasting subjects on the first and last day of each period. Cholesterol and triacylglycerol (TG) synthesis rates were determined using deuterated water uptake rate over the last 24 h of each period. Postprandial blood lipids, and glucose and insulin were assessed in 11 subjects on d 28. Fasting serum cholesterol was unchanged; however, when expressed as a percentage change, TG were decreased, relative to baseline (P < 0.04), by L-rhamnose (-10%) and lactulose (-10%), compared with D-glucose, which increased serum TG (+11%). Net TG-fatty acid (TGFA) synthesis on d 28 was lower with L-rhamnose (2.42 +/- 0.38 g/d) and lactulose (2.62 +/- 0.35 g/d) than with D-glucose (2.96 +/- 0.31 g/d, P < 0.01). We conclude that these results do not support a primary role for propionate in the cholesterol-lowering effect of soluble fiber. However, both lactulose and L-rhamnose lowered serum TG (expressed as a percentage change) and TGFA synthesis, compared with d-glucose, which increased them. Although these data are consistent with inhibition of TGFA synthesis by SCFA, other aspects of the metabolism of these sugars cannot be ruled out as putative agents of their TG-lowering effects.

The relevance of the glycaemic index to our understanding of dietary carbohydrates

AIMS

To review the evidence for the importance of glycaemic index of dietary carbohydrate in disease prevention and control.

METHODS

A critical appraisal of the literature published in English between and cited on Medline between January 1966 and October 1999.

RESULTS

Using basic, intervention and epidemiological studies from experienced teams, evidence that the glycaemic index of diet may influence outcome in terms of cardiovascular risk, risk of metabolic syndrome diseases and pregnancy was found.

CONCLUSIONS

Consideration of glycaemic indices in making dietary recommendations may be expected to produce additional health benefit.