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Effects of intermittent fasting on inflammation and oxidative stress

Goal: We're trying to determine whether intermittent fasting, restricting calorie consumption to one 8-hour window per day followed by a 16-hour fast, can significantly decrease inflammation and/or oxidative stress. We'll be doing ELISAs to monitor salivary concentrations of IL-1b and reduced glutathione.

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Shawn Stover
added a research item
Previous research has consistently demonstrated that regular exercise promotes antioxidant production and decreases the expression of inflammation markers. However, there is very little research examining the effects of intermittent fasting (IF) on oxidative stress and inflammation. The present study investigated the hypothesis that a combination of IF and physical activity will reduce the need for glutathione (GSH) production by decreasing oxidative stress. In addition, it was hypothesized that a combination of IF and physical activity will significantly reduce inflammation, as indicated by a decrease in interleukin-1b (IL-1b) concentration. For three months, subjects practicing IF (n=7) ate only during an eight-hour window each day and fasted for the next 16 hours. A standard diet control group (n=18) maintained a normal, balanced diet spread out over the course of 14-18 hours each day. Based on data obtained from fitness-tracking devices, subjects were placed into one of three activity level groups: minimum, moderate, and maximum physical activity. Subjects provided fasting saliva samples monthly. The samples were subjected to a glutathione microplate assay and an interleukin ELISA test to determine salivary concentrations of GSH and IL-1b, respectively. For GSH concentration, there were no significant differences between the diets at any physical activity level. However, moderate to maximum physical activity, in conjunction with fasting, led to significant decreases in IL-1b concentration. In summary, results suggest that a combination of moderate physical activity and intermittent fasting promotes the maintenance of antioxidant function while inhibiting the inflammatory process.
Shawn Stover
added a research item
Obesity is associated with serious health risks, including cardiovascular disease, diabetes mellitus, and certain cancers. However, evidence suggests that long-term dieting might actually slow down metabolic rate, making it difficult to maintain a healthy body weight. Intermittent fasting (IF) is a method of caloric restriction that involves alternating periods of fasting and non-fasting. The present study investigated the hypothesis that a combination of IF and exercise will allow resting metabolic rate (RMR) to be maintained long-term. Furthermore, it was hypothesized that a combination of IF and exercise will significantly decrease the respiratory quotient (RQ), an estimate of macronutrient utilization. For 3 months, subjects practicing IF ate only during an 8-hr window each day and fasted for the next 16 hrs. A standard diet control group maintained a normal diet spread out over the course of 14 to 18 hrs each day. Based on the data obtained from fitness-tracking devices, the subjects were placed into 1 of 3 activity level groups: minimum exercise, moderate exercise, and maximum exercise. Indirect calorimetry was employed to determine RMR and RQ. No significant differences were found between the 2 groups of subjects at any activity level, suggesting that IF does
Shawn Stover
added an update
We have two years of data on the effects of intermittent fasting on oxidative stress (by measuring salivary concentration of the antioxidant glutathione) and inflammation (by measuring salivary concentration of the inflammation marker IL-1b), and one year of data on the effects of intermittent fasting on resting metabolic rate (by measuring the ratio of oxygen consumed to carbon dioxide exhaled).
We’ll be collecting data for one more year, then I’ll write up a paper (or two) and submit for publication. As of now, these are the preliminary conclusions:
In terms of salivary glutathione concentration, there was no significant difference between the standard diet and intermittent fasting. Even as exercise level increased, glutathione remained consistent. Because glutathione is depleted during exercise, the production of glutathione must have been upregulated to maintain a stable concentration.
It appears that intermittent fasting produces far less inflammation than the standard diet (as indicated by IL-1b production). Moderate to maximum exercise, in conjunction with fasting, led to significant decreases in inflammation.
Results indicate that intermittent fasting does not slow resting metabolic rate. Exercise level, however, had a major impact on resting metabolism.
 
Shawn Stover
added an update
We have two primary groups of participants in the study since the fall of 2016. One group maintained a standard diet with meals taken throughout the day (n=11). The other group practiced intermittent fasting, taking all meals within an eight-hour period, followed by a 16-hour fast (n=5).
We’ve analyzed all saliva samples for Interleukin-1b (IL-1b), a pro-inflammatory protein that is generated in response to physiological stressors. According to previous research, the average salivary concentration of IL-1b is about 122 pg/ml. The standard diet group had a mean IL-1b concentration of 121 pg/ml, while the intermittent fasting group had a mean of only 41 pg/ml.
We’ve also analyzed the saliva samples for total glutathione (GSH), the body’s primary antioxidant. The standard diet group had a mean GSH concentration 9.7 micromolar, while the intermittent fasting group had a mean of 7.0 micromolar. Published research suggests that 10 micromolar is about average.
When we controlled for the effects of daily exercise, we found that minimum exercise (fewer than 8,000 steps/day) paired with intermittent fasting produced an average IL-1b concentration (92.6 pg/ml) not much different from that of the standard diet group (105.8 pg/ml). However, moderate (between 8,000 and 12,000 steps/day) and maximum daily exercise (more than 12,000 steps/day) generated IL-1b concentrations (22.5 and 33.5 pg/ml, respectively) that were much lower than those of the standard diet group. GSH concentrations remain relatively stable in both fasting (between 6.6 and 7.6 mM) and standard diet (between 7.9 and 11 mM) groups, regardless of exercise level. Since GSH is oxidized more often during exercise, this suggests an increase in GSH production to compensate.
 
Shawn Stover
added an update
Saliva samples from our spring volunteers have been analyzed. As of now, subjects practicing intermittent fasting (n=4) have generated an average IL-1b concentration of 44 pg/ml, while subjects on a standard diet (n=7) generated an average concentration of 222 pg/ml. The intermittent fasting group also generated an average glutathione concentration of 7.4 uM, while the standard diet group generated an average of 12.8 uM. Sample sizes are still very small, so no statistics have been done. Furthermore, we still have to correct for any exercise effect.
We will be continuing the study in fall with new volunteers. In addition, we recently got funding for a metabolic testing system. Starting in the fall, we will also be able to assess the resting metabolic rates of our research subjects, allowing us to better determine the effectiveness of intermittent fasting.
 
Shawn Stover
added an update
We’ve analyzed the saliva samples for total glutathione (GSH), the body’s primary antioxidant.
The standard diet group had a mean GSH concentration 8.3 mM, while the intermittent fasting group had a mean of 7.4 mM. Both values are within the normal range.
 
Shawn Stover
added an update
We’ve analyzed the saliva samples for Interleukin-1b (IL-1b), a pro-inflammatory protein that is generated in response to physiological stressors. According to previous research, the average salivary concentration of IL-1b is about 122 pg/ml.
We had two groups of participants in the first round of our study. One group maintained a standard, balanced diet with meals taken throughout the day. The other group practiced intermittent fasting, taking all meals within an eight-hour period, followed by a 16-hour fast. Both groups had IL-1b levels that were lower than average.
The standard diet group had a mean IL-1b concentration of 74 pg/ml, while the intermittent fasting group had a mean of 44 pg/ml. Currently, the sample size is too small to do any analysis of statistical significance, and I haven’t looked at any impact of exercise yet.
 
Shawn Stover
added a project goal
We're trying to determine whether intermittent fasting, restricting calorie consumption to one 8-hour window per day followed by a 16-hour fast, can significantly decrease inflammation and/or oxidative stress. We'll be doing ELISAs to monitor salivary concentrations of IL-1b and reduced glutathione.