Excessive fructose consumption is believed to be one of the main causes of metabolic syndrome.
Fructose makes up 50% of table sugar, which is the most commonly consumed sweetener in the world.
A recent study, published in Pediatric Obesity, investigated whether replacing sugar with starch would improve markers of metabolic syndrome in children.
Here is a detailed summary of the findings.
Additionally, type 2 diabetes is more common than obesity in Chinese and Indian children. This indicates that metabolic syndrome is not solely explained by excessive calorie intake (2).
In fact, one of the main suspects is fructose, a type of sugar found in virtually all sugar-sweetened foods.
Fructose has several properties that make it particularly unhealthy when eaten in high amounts:
- Liver fat accumulation: Excessive intake leads to liver fat accumulation and increases the risk of non-alcoholic fatty liver disease (3, 4, 5).
- Oxidative stress: Fructose increases oxidative stress, which may disrupt cellular function (6).
- Overeating: Fructose does not suppress appetite as efficiently as glucose, and may therefore promote overeating (7, 8).
For these reasons, limiting fructose from added sugars may have many health benefits.
Researches from California set out to investigate the metabolic effects of replacing sugar with starch for children with obesity and metabolic syndrome.
Basic Study Design
This 9-day trial in 43 obese children with metabolic syndrome investigated the short-term health effects of reducing sugar and fructose.
The participants’ normal diets were characterized by high amounts of added sugar. Their average sugar intake was 28% of total calories.
To examine the effects of fructose restriction, the participants followed a weight-maintenance diet that reduced sugar and fructose to 10% and 4% of total calories, respectively, and replaced it with starch.
The diet contained similar proportions of protein, fat and carbs as their habitual diet before the study.
At the beginning and end of the study, the researchers measured body composition, blood sugar, insulin, blood pressure and blood lipids.
Bottom Line: This was a 9-day trial in obese children with metabolic syndrome. Its purpose was to examine the health effects of reducing dietary sugar and fructose and replacing it with starch.
Finding 1: Eating Less Fructose Improved Blood Pressure
During the study period, diastolic blood pressure decreased by 4.9 mmHg, on average.
Conversely, systolic blood pressure did not decrease significantly.
Bottom Line: Reducing sugar intake significantly improved diastolic blood pressure, but not systolic blood pressure.
Finding 2: Less Dietary Sugar Improved Blood Lipids
The blood lipid profile also improved significantly during the study:
- Fasting triglycerides: -46%.
- LDL-cholesterol: -13%.
Bottom Line: Eating less fructose improved the blood lipid profile, causing a significant reduction in fasting triglycerides and LDL-cholesterol.
Finding 3: Eating Less Sugar Improved Blood Sugar Control
Blood sugar control improved substantially during the course of the study:
- Fasting blood sugar: -6%.
- Fasting insulin: -53%.
- Peak insulin: -56%.
- Insulin resistance: -58%, according to HOMA-IR.
Also, the body’s response to glucose ingestion improved significantly, according to the results of an oral glucose tolerance test.
These improvements were not associated with either weight loss or a calorie deficit. This suggests that the benefits were mostly caused by the reduction in sugar intake.
Bottom Line: Reducing sugar intake improves blood sugar control, fasting blood sugar, fasting insulin and insulin resistance.
Finding 4: Eating Less Sugar Caused Weight Loss
During the study, body weight decreased by 1%, or 0.9 kg (2 lbs), on average.
Since the participants were supposed to have been on a weight-maintenance diet, the weight loss is probably not explained by substantial fat loss.
There are a few factors that likely contributed to the weight loss:
- Reduced water retention: Less sugar intake may have decreased water retention. The weight loss took place in the first 4 days, suggesting loss of water weight.
- Decreased lean mass: Lean mass decreased significantly, or by 0.6 kg (1.3 lbs). Since water weight is a part of the lean mass measurement, this further supports that the weight loss may have been due to reduced water retention.
- Less food intake: 77% of the participants reported that they were unable to eat all of the food provided by the researchers. This may have led to weight loss. However, fat mass reduction was not significant, according to DXA.
Although most participants did lose weight, a total of 10 participants did not lose weight during the study. However, these participants still experienced health benefits similar to the children who did lose weight.
The researchers concluded that the health benefits seen in the present study could not be explained by the small amount of weight loss.
Bottom Line: Overall, the participants lost weight during the study. This weight loss may be largely attributed to less water retention.
This was a well-designed and well-executed study. However, there were a few limitations.
By replacing sugar with starch and adding fiber, the overall glycemic index of the diet was reduced.
It is possible that some of the findings were, at least, partly caused by a reduction in the glycemic index of the diet, rather than a decrease in fructose (13).
Also, the study had no control group. For this reason, we do not know if other study-related factors had an effect.
Bottom Line: The study was designed well and there is no reason to doubt the results. The findings are also supported by previous studies.
Summary and Real-life Application
The study showed that eating less sugar has multiple health benefits.
In summary, reducing sugar and fructose intake:
- Reduced blood pressure.
- Lowered blood cholesterol.
- Decreased triglyceride levels.
- Improved blood sugar control.
These results happened in only 9 days. Restricting fructose for a longer period of time may have resulted in even greater health benefits.
Simply put, reducing your intake of added sugar is one of the best things you can do for your health.