Research

Health and nutrition are complex subjects. Food and health fashions, fads and crazes make the process of discovering what works for us as individuals even harder.

We want to help make things a little clearer, so we fund independent studies, run by academics at local universities to test the real impact of using Human Food as part of your diet. These studies also help us understand our recipes better, and play a big role in deciding where to take things next.


Time-course of changes in blood glucose concentration, satiety and decision making following ingestion of Human Food (3 varieties) in healthy individuals.

Dr RM Bracken 6.01.2020.
Swansea University, Applied Sport, Technology, Exercise and Medicine Research Centre (A-STEM)


Summary

Aims

To determine, over a 2 hr. period, following the ingestion of Human Food bars (3 varieties), changes in; Blood glucose concentration; Satiety (perceived fullness) and decision making responses, compared to a matched control, in healthy individuals.

Methods

Participants visited the laboratory on 4 separate occasions within a 10 week period. Participants ingested a test bar – one of 3 varieties of Human Food bar – or a control meal containing matched carbohydrate, with 250 ml water, delivered in a randomised, double blind fashion and consumed within a 5-minute period. Blood samples, measures of satiety using the McKinley Scale and decision making via the Stroop Colour Word Test were then taken at 15, 30, 45, 60, 90 and 120 mins. Participants remained seated for the entire observation period.

Results

Ingestion of all three bars produced a significantly lower peak blood glucose concentration and fewer occurrences of hypoglycaemia* over the 2-hour period compared with the control. The immediate, mean and 2 hour fullness response were greater under all bar conditions compared with the control, and under all bar conditions satiety remained significantly above rest level at the end of the 2 hr observation period. Ingestion of all three bars demonstrated improved mean reaction responses compared with the control, with the Yellow Bar demonstrating statistically significant responses.

*(BG≤3.9 mmol/l)

Conclusion

All bars demonstrated low blood glucose responses and sustained satiety over the duration of the 2 hour observation period. The combination of a low blood glucose response combined with sustained satiety is conducive to maintaining a healthy balanced diet that’s proportional in calories to the needs of the body.

In reaction tests, all bars produced a greater number of completed responses, as well as more accurate and faster responses compared with the control, over the entire observation period. For the Green Bar in all tests and for the Red Bar in 2 out of 4 tests, the data spread was too broad to be considered statistically significant. The Yellow Bar demonstrated statistically significant improvements in all tests, with an average improvement in reaction time of over 10%.


Read the full study below:

Aims

To determine:

  • Changes in blood glucose over a 2 hour period following ingestion of Human FoodTM bar range (3 varieties) compared to matched amount of dextrose in healthy individuals.
  • Satiety scores recorded by participants following consumption of test bars and control food.
  • Decision making test response by participants following consumption of test bars and control food.

Methods

Study

Ten subjects (n=10) were recruited from the local University population. Inclusion of both sexes.

Characteristic Values (range or mean±SD)

Males:Females

8:2

Age (years)

20-22 years

Mass (kg)

72±20

Height (m)

1.78±0.10

BMI (kg/m2)

24.1±4.3

Table 1. Anthropometric characteristics of participants.

Participants attended the laboratory on four occasions, sessions were held twice a week over a period of 8-10 weeks. Each participant took part in 3 trials on different Human FoodTM bars and one trial of carbohydrate-matched control (dextrose), in randomised, double-blind control trial.

Participants were asked to avoid strenuous activity for 48 hours before attendance at each laboratory visit and avoid food for 10 hours before attending the laboratory. On arrival to the laboratory fasted, participants were seated for 15 min whilst informed consent and pre-medical questionnaires were completed. Following this, anthropometric characteristics (height and weight) were recorded.

Participants were then re-seated and 10 minutes later a resting finger capillary blood sample was taken and analysed immediately for blood glucose and lactate (EKF Biosen, C-line metabolic analyser). Next, and in a randomised fashion, participants ingested the test bar or dextrose meal containing either matched available carbohydrate (22 g CHO) with 250 ml of water or equivalent amounts of dextrose with 250 ml water. All foodstuffs were consumed within a 5-minute period. Blood samples were taken at rest, and at 15, 30, 45, 60, 90, 120 min following ingestion. Measures of satiety using the McKinley Scale and decision making, via the Stroop Colour Word Test was also taken at these time-points. Participants remained seated for the post-ingestion period. Hypoglycaemia was defined against American Diabetes Association criteria of BG≤3.9 mmol/l.

Analysis

Statistical analysis was carried out using Excel (Microsoft Office), with significance set at P≤0·05. Data were tested for normal distribution (Shapiro – Wilk test) and subsequently analysed using one way or repeated-measures ANOVA on two factors (treatment and time) with Bonferroni adjustment and dependent t-tests being carried out where relevant. Data are reported as means with their standard deviation.

Results

Blood Glucose

The glycaemic responses to food bars and reference meal are reported in Figure 1.

Fasting BG concentrations were similar between the reference meal and all bar conditions. Mean BG concentrations over the two-hour ingestion period were similar across all conditions (CON 5.2±0.7, RED 4.8±0.5, GREEN 4.7±0.5, YELLOW 4.8±0.5 mmol/l).

Peak BG concentrations were lower under all bar conditions than unxader the dextrose condition (RED 5.6±0.6, GREEN 5.5±0.4, YELLOW 5.5±0.7 mmol/l) vs. CON 7.2±0.9 mmol/l, P<0·0083). Time to reach peak BG concentrations did not differ amongst any trials.

Lowest BG concentrations occurred under reference dextrose condition compared with all the bars (CON 3.6±0.6 mmol/l vs. RED (4.1±0.5 mmol/l), GREEN (4.0±0.7 mmol/l), YELLOW (4.3±0.6 mmol/l), P<0·05)). There was no difference in the time at which the lowest BG occurred under any condition.

There were fewer occurrences of hypoglycaemia (BG≤3.9 mmol/l) under all bar conditions compared with dextrose meal (CON 8/10 participants, RED 3/10 participants GREEN 4/10 participants YELLOW 4/10 participants).

Figure 1. Blood glucose concentration responses to food bars and reference meal over a 2 hour ingestion period (means±SD, n=10). * indicates significant difference between CON and all bar varieties at indicated timepoints (P<0.05) Within trial differences not indicated for clarity.

Blood Lactate

The blood lactate concentration responses to ingestion of food bars and reference meal are reported in Figure 2.

Fasting blood lactate concentrations were similar between the reference meal and all bar conditions.

Peak blood lactate concentrations were greater under all bar conditions than under the dextrose condition (RED 1.6±0.3, GREEN 1.7±0.4, YELLOW 1.8±0.4 mmol/l) vs. CON 1.4±0.3 mmol/l, P<0·05), with no differences between bars.

Figure 2. Blood lactate concentration at rest and following ingestion of food bars and reference meal over a 2-hour period (means±SD, n=10). * indicates significant difference between CON and all bar varieties at indicated timepoints (P<0.05) Within trial differences not indicated for clarity.

Hunger/Satiety

The perception of hunger responses to food bars and reference meal are reported in Figure 3.

Fasting hunger responses were similar between the reference meal and all bar conditions. The average fullness response was greater under all bar conditions than under the dextrose condition (RED 4.5±0.7, GREEN 4.2±0.9, YELLOW 4.4±0.8 AU) vs. CON 3.1±0.5 AU, P<0·05), with a higher fullness value found between RED and GREEN bars (P=0.048).

The fullness response taken at 2-h was greater under all bar conditions than under the dextrose condition (RED 4.4±0.8, GREEN 3.6±0.7, YELLOW 3.8±0.9 AU) vs. CON 2.6±0.8 AU, P<0·05), with a significant greater fullness value in RED compared to both GREEN (P=0.022) and YELLOW (P=0.005) bars, respectively.

Figure 3. Perception of Hunger responses to ingestion of food bars and reference meal over a 2-hour period (means ± SD, n=10). * indicates significant difference between CON and all bar varieties at indicated timepoints (P<0.05) Within trial differences not indicated for clarity.

Reaction Time

The responses to Stroop Colour Word Test are reported in Table 2.

The number of correct responses measured at 2 h was similar in all trials, however, YELLOW displayed a greater value compared to dextrose trial (CON 69±11 YELLOW 75±8, P=0.048, Table 2.).

Stroop Colour Word Test CONTROL RED GREEN YELLOW

Number of Responses at rest

68±15

73±12

69±11

75±8

Number of Responses at 2 h timepoint

72±12

79±11

75±13

78±8*

Total Number of Responses over 2 h period

430±69

463±62

434±68

461±43

Number of correct responses at rest

65±14

69±10

68±10

71±7

Number of correct responses at 2 h timepoint

69±11

74±09

72±11

75±8*

Total Number of Correct Responses over 2h period

413±58

439±52

417±60

441±40*

Time per response at rest (s)

0.94±0.25

0.85±0.16

0.88±0.13

0.81±0.08

Mean Time per response over 2 h (s)

0.86±0.14

0.79±0.10†

0.85±0.13

0.79±0.07*

Time per response at 2 h timepoint (s)

0.85±0.14

0.78±0.11

0.82±0.14

0.78±0.07*

Time per correct response at rest (s)

0.07±0.25

0.88±0.16

0.91±0.12

0.85±0.09

Mean Time per correct response over 2 h (s)

0.0±0.13

0.83±0.10†

0.88±0.12

0.82±0.08*

Time per correct response at 2 h timepoint (s)

0.86±0.14

0.78±0.11†

0.82±0.14

0.78±0.08*

Table 2. Responses and Time per response to ingestion of food bars or control meal over 2 hour (means ± SD, n=10). * significant difference between CON and YELLOW (P<0.05). † significant difference between CON and RED (P<0.05).

The average percentage of correct responses in absolute counts was similar across all trials. Also, the percentage of correct responses at 2 h was similar. The average time per response and the average time per correct response was similar at rest across all trials.

The time per response was similar in all trials except dextrose and YELLOW trial (CON 0.85±0.14 vs. YELLOW 0.78±0.08 s, P=0.041). Finally, the time taken per correct response at 2 h after ingestion was significantly faster in RED and YELLOW bars compared with dextrose trial (RED 0.82±0.10 YELLOW 0.81±0.08 vs. CON 0.91±0.15 s, P<0.05).

Discussion

Blood Glucose

Ingestion of all three bars produced a significantly lower peak BG concentration compared with dextrose. All three bars produced a BG value that was higher than dextrose when measured at 2-hours. There were fewer occurrences of hypoglycaemia (BG≤3.9 mmol/l) over the 2-hour period under all bar conditions compared with dextrose meal (CON 8/10 participants, RED 3/10 participants GREEN 4/10 participants YELLOW 4/10 participants). There was no within bar differences in BG concentration at any time point.

Foods with a low glycaemic response have significant health benefits because from a public perspective, a lower glycaemic response is related to greater feelings of satiety and fullness which prevents the need to eat additional foodstuffs and may aid in weight loss. Low glycaemic index (GI) foods are correlated to a lower insulin demand and may improve long-term blood glucose control and blood lipids for those at risk of developing or already with diabetes. Additionally, knowledge of the GI of a food may help maintain good glucose control and avoid hypoglycaemic incidents. The lower (but not absent) occurrences of clinical hypoglycaemia under the bar ingestion trials compared to dextrose is a positive finding.

It must be stated that we did not determine the glycaemic index of the Human FoodTM bars in this experiment as to do so would require larger amounts of dextrose and necessitate consumption of ~4 bars to match carbohydrate intake. This project sought to determine the glycemic impact of a typical serving size.

Effect of GI on Pre-Diabetes and Diabetes

Different carbohydrate foods are digested in vitro at different rates which are, in turn, directly related to the blood glucose and insulin responses they elicit (Wolever et al., 1988). The incorporation of low glycaemic response foods into mixed meals reduces glucose and insulin concentrations in normal and diabetic subjects (Chew et al., 1988; Indar-Brown et al., 1992). Wolever et al., (2002) demonstrated that high carbohydrate-low GI dietary advice over 4 months improved β-cell function in impaired glucose tolerance (IGT) subjects. Several meta-analyses have demonstrated that low GI diets reduce HbA1c or fructosamine in subjects with or without diabetes (Brand-Miller et al., 2003; Kelley et al., 2004; Opperman et al., 2004).

A long-term (1 year) multicentre, randomised control trial compared the potential of an alteration in the source of carbohydrate with the effect of reducing the amount of carbohydrate on glycosylated haemoglobin and secondary endpoints such as blood glucose, lipids and CRP in 162 patients with T2DM managed with diet alone. There were sustained reductions in post-prandial glucose and CRP in the low-GI diet group compared to high GI or low carbohydrate content groups. In the low GI group after the 1 year intervention, 2-h post-OGTT glucose concentrations were ~1 mmol.l-1 lower than those seen in the other two diets – a difference that, in prospective studies represents a 6-15% reduction in cardiovascular events (Coutinho et al., 1999; Meigs et al., 2002). Additionally, the results demonstrated improved CRP concentrations, insulin sensitivity and β-cell function in the low GI diet group. Therefore, these results demonstrate that a low GI diet might be an option for dietary management of T2DM.

Effect of GI on Preparation and Recovery Strategies in Sports and Exercise

Performance of physical exercise increases the demand for energy. Compensation for energy expenditure comes from ingestion of carbohydrates, fat and protein. Regarding carbohydrate, energy release is three times as fast as from fat but is limited to stores in the muscle and liver. Adequate carbohydrate ingestion before, during and after exercise replenishes carbohydrate stores and prevents increased use of protein for energy production (Waganmakers et al., 1991). The choice of specific low-, medium- or high-GI carbohydrates may be dependent on the functional outcome to be gained i.e. pre-exercise preparatory carbohydrate ingestion to provide energy during exercise or post-exercise replenishment of muscle and liver carbohydrate stores.

It is evident from the literature that an increase in fat oxidation (and reduced carbohydrate oxidation) occurs during exercise after consumption of a pre-exercise low-GI carbohydrate compared to an isocaloric high GI carbohydrate (Stevenson et al., 2005 and 2006; Wee et al., 2005; Wu et al., 2003 and 2006). Therefore, the role of consumption of a low GI carbohydrate source in maintaining blood glucose carbohydrates for longer might preserve exercising glucose concentrations and extend prolonged endurance performance. Interestingly, a high GI CHO 3 h before exercise was more effective in increasing muscle glycogen concentrations compared to a low GI carbohydrate (Wee et al., 2005). More muscle glycogen stores were also used during exercise in the high GI trial whereas the low GI meal demonstrated an increased fat oxidation rate, potentially demonstrating how low GI pre-exercise meals preserve muscle glycogen concentrations and allow for more sustained carbohydrate availability over the endurance exercise.

Wu et al., (2008) have demonstrated that consumption of a low GI meal 2 h before exercise results in better endurance running performance compared to high GI meals. Additionally, Wong et al., 2008 demonstrated all subjects ran faster over 16 km following consumption of a low GI meal 2 h before exercise compared with a high GI meal. Muscle glycogen sparing was thought to be the working mechanism evidenced by a higher fat oxidation rate.

Several studies have reported that the GI can play a significant role in exercise recovery (Erith et al., 2006; Stevenson et al., 2005a; 2005b; Siu et al., 2004). Carbohydrate ingestion has repeatedly been shown to increase post-exercise glycogen replenishment (Ivy et al., 1988; Tsintzas et al., 2003). The amount and timing have of post-exercise carbohydrate have been widely examined and standard guidelines produced (Hawley et al., 1997; Burke et al., 2001). The recommended type of carbohydrate is still a matter of debate. In relation to resistance exercise, standard nutritional guidelines recommend ingesting a combination of carbohydrate and protein to maximise recovery (Manninen et al., 2006). The timing of post-exercise recovery is important as studies have shown positive carbohydrate replenishment of high GI in the immediate post-exercise period whereas low or high GI can be consumed if recovery extends beyond 24 h if sufficient amounts of carbohydrate are consumed (Kiens et al., 1990; Burke et al., 1993; Pitsiladis et al., 1999; Lambert et al., 1997).

Blood Lactate

The raised lactate concentrations in all bar trials compared with dextrose demonstrate the potentially higher fructose levels contained in fruit. The concentrations are low and are similar across all three bar varieties. Low values like this, which are just above resting levels, are an indication that metabolism was being provoked to marginally elevated lactate concentrations. After an hour to an hour and a half, the lactate was starting to disappear, landing at values that are indistinct from resting values.

Hunger/Satiety

The mean and 2 hour fullness response were greater under all bar conditions compared with the dextrose condition, however we must be cautious here as the total energy load was different in the bars compared with just dextrose powder. There was however, a significant difference found between the RED and GREEN bars (P=0.048) for mean fullness response and between the RED and both GREEN (P=0.022) and YELLOW (P=0.005) bars, respectively for 2 hour fullness.

There is evidence obtained from systematic scientific literature reviews to demonstrate substantiation of the health claim ‘low-GI foods help one feel fuller for longer than equivalent high-GI foods’, as short-term satiety is improved after consumption of low GI compared to high GI foods (Bornet et al., 2007). However, due to the growing number of confounding variables in longer-term studies it is difficult to demonstrate a satietogenic effect on low GI foods.

Reaction Time

Number of Responses

All 3 bars demonstrated higher mean values for the number of responses at resting, at 2 hours and over the 2 hour time period. However, only the Yellow bar demonstrated a statistically significant improvement compared with the control at 2 hours.

Number of Correct Responses

All 3 bars showed a higher mean value of correct responses at resting, at 2 hours and over the 2 hour time period. However, only the Yellow bar demonstrated a statistically significant increase in the number of correct responses at 2 hours.

Time per Response

All 3 bars demonstrated lower mean values for the time per response at resting, at 2 hours and over the 2 hour time period. However, only the Yellow bar demonstrated a statistically significant improvement compared with the control at 2 hours and over the 2 hour period. The Red bar demonstrated an improvement in time per response over the 2 hour period but to a lesser degree than the Yellow bar.

Time per Correct Response

All 3 bars demonstrated lower mean values for the time per correct response at resting, at 2 hours and over the 2 hour time period. However, only the Yellow bar demonstrated a statistically significant improvement compared with the control at 2 hours and over the 2 hour period. The Red bar demonstrated an improvement in time per correct response at 2 hours, but to a lesser degree than the Yellow bar.

Reaction tests have the ability to measure the overall effect of the tested product on recognition, reaction and movement time. YELLOW (and to a lesser consistent extent RED) bars aided faster decision-making, reaction/movement time compared with the control condition. Curcumin (400 mg Turmeric) has been shown to significantly improve performance on sustained attention and working memory tasks, compared with the placebo. Working memory and mood (general fatigue and change in state calmness, contentedness, and fatigue induced by psychological stress) were significantly better following chronic treatment. A significant acute-on-chronic treatment effect on alertness and contentedness was also observed. (Cox, K.H.; Pipingas, A.; Scholey, A.B. .J. Psychopharmacol.2015,29, 642–651.). A randomized, double-blind, placebo-controlled, study of the effects of Goji juice revealed 14 days consumption daily improved mental acuity, (Amagase and Nance (2008) J Alternative Complementary Medicine., 14 (4), 403-12 May 2008) however, it is not clear from the literature if an acute supplement can carry over the same effect.

Conclusion

In conclusion, the aim of this pilot study was to determine the magnitude of changes in blood glucose, sati-ety scores, and decision making over a 2 hour period following ingestion of all Human FoodTM bar range (3 varieties) compared to matched amount of dextrose in healthy individuals. The results reveal a low glycaemic response in all three bars, with RED bars displaying a higher mean fullness response than the GREEN bar. At 2 h, the RED bar displayed a higher fullness than both the GREEN (P=0.022) and YELLOW (P=0.005) bars, respectively.

All bars showed an initial rise in perceived fullness that was sustained throughout the whole two hour observation period. The combination of a low, blood glucose response combined with sustained satiety is conducive to maintaining a healthy balanced diet that's proportional in calories to the needs of the body.

In reaction tests, all bars produced a greater number of completed responses, as well as more accurate and faster responses compared with the control, over the entire observation period. For the Green Bar in all tests and for the Red Bar in 2 out of 4 tests, the data spread was too broad to be considered statistically significant. The Yellow Bar demonstrated statistically significant improvements in all tests, with an average improvement in reaction time of over 10%.