Ketonuria may be associated with low serum amylase independent of body weight and glucose metabolism

Fasting Ketonuria and the Risk of Incident Nonalcoholic Fatty Liver Disease With and Without Liver Fibrosis in Nondiabetic Adults

INTRODUCTION

Dietary carbohydrate restriction or ketogenic diets are known to be beneficial in preventing liver fat accumulation. However, the effect of ketonemia on the risk of nonalcoholic fatty liver disease (NAFLD) in nondiabetic population is largely unknown. We investigated the association between fasting ketonuria and the risk of incident NAFLD in healthy adults.

METHODS

A cohort of 153,076 nondiabetic Koreans with no hepatic steatosis and low probability of fibrosis at baseline was followed for a median of 4.1 years. The outcome was incident hepatic steatosis with or without liver fibrosis, and it was assessed by liver ultrasound and noninvasive fibrosis indices, including fibrosis-4 and the NAFLD fibrosis score (NFS). Parametric proportional hazard models were used to estimate hazard ratios (HRs) for outcome according to ketonuria status.

RESULTS

Within 677,702.1 person-years of follow-up, 31,079 subjects developed hepatic steatosis. Compared with no ketonuria (reference), fasting ketonuria was significantly associated with a decreased risk of incident hepatic steatosis, with multivariable-adjusted HRs (95% confidence interval) of 0.81 (0.78-0.84). The corresponding HRs for incident hepatic steatosis with intermediate-to-high NFS were 0.79 (0.69-0.90). Similar associations were observed replacing NFS with fibrosis-4. In addition, the presence of persistent ketonuria at both baseline and subsequent visit was associated with the greatest decrease in the adjusted HR for incident NAFLD.

DISCUSSION

Ketonuria was associated with a reduced risk of developing incident hepatic steatosis with and without intermediate-to-high probability of advanced fibrosis in a large cohort of nondiabetic healthy individuals. The role of hyperketonemia in the prevention of NAFLD requires further exploration.

Ethnic-specific association of amylase gene copy number with adiposity traits in a large Middle Eastern biobank

Studies assessing the impact of amylase genes copy number (CN) on adiposity report conflicting findings in different global populations, likely reflecting the impact of ancestral and ethnic-specific environment and lifestyle on selection at the amylase loci. Here, we leverage population size and detailed adiposity measures from a large population biobank to resolve confounding effects and determine the relationship between salivary (AMY1) and pancreatic (AMY2A) amylase genes CN and adiposity in 2935 Qatari individuals who underwent whole-genome sequencing (WGS) as part of the Qatar Genome Programme. We observe a negative association between AMY1 CNs and trunk fat percentage in the Qatari population (P = 7.50 × 10^-3) and show that Qataris of Arab descent have significantly lower CN at AMY1 (P = 1.32 × 10^-10) as well as less favorable adiposity and metabolic profiles (P < 1.34 × 10^-8) than Qataris with Persian ancestry. Indeed, lower AMY1 CN was associated with increased total and trunk fat percentages in Arabs (P < 4.60 × 10^-3) but not in Persians. Notably, overweight and obese Persians reported a significant trend towards dietary restraint following weight gain compared to Arabs (P = 4.29 × 10^-5), with AMY1 CN showing negative association with dietary self-restraint (P = 3.22 × 10^-3). This study reports an association between amylase gene CN and adiposity traits in a large Middle Eastern population. Importantly, we leverage rich biobank data to demonstrate that the strength of this association varies with ethnicity, and may be influenced by population-specific behaviors that also contribute to adiposity traits.

The association of low serum salivary and pancreatic amylases with the increased use of lipids as an energy source in non-obese healthy women

OBJECTIVE

It is unknown whether low serum levels of salivary and pancreatic amylases are associated with the high combustion of carbohydrates or lipids for energy. Elevated blood ketones and a low respiratory quotient (RQ) can reflect the preferential combustion of lipids relative to carbohydrates. Therefore, using the data from our previous study, we investigated if low levels of serum amylases were associated with a high serum ketone level and low RQ in 60 healthy non-obese young women aged 20-39 years old.

RESULTS

Serum ketones [3-hydroxybutyric acid (3-HBA) and acetoacetic acid (AA)] were inversely correlated with RQs, but not body mass index (BMI) or glycated haemoglobin (HbA1c) levels. Logistic regression analysis showed that high levels of serum ketones (3-HBA ≥ 24 μmol/L and AA ≥ 17 μmol/L) and a low RQ (< 0.766) were significantly associated with low serum salivary (< 60 U/L) and pancreatic (< 29 U/L) amylase levels, respectively. These associations were not altered by further adjustments for age, BMI, HbA1c, and estimated glomerular filtration rate. These results confirm the high combustion of lipids for energy in individuals with low serum amylase levels, suggesting a close relationship between circulating amylases and internal energy production.

Copy Number Variation of the Salivary Amylase Gene and Glucose Metabolism in Healthy Young Japanese Women

BACKGROUND

Many studies have shown that low copy number variation (CNV) of the salivary amylase gene (AMY1) and low serum amylase concentration are associated with impaired glucose metabolism and obesity. We aimed to clarify the conflicting results of previous studies by examining AMY1 expression and metabolic indices in a homogenous group of healthy participants.

METHODS

Sixty healthy non-obese young Japanese women aged 20 - 39 years were examined for AMY1 CNV, salivary amylase, body mass index (BMI) and serum parameters including glycated hemoglobin (HbA1c), ketones, and total, salivary and pancreatic amylase. Respiratory quotient at rest and changes in blood glucose after starch loading were also examined.

RESULTS

AMY1 CNV (range, 4 - 14) and the level of serum salivary amylase were correlated inversely with HbA1c (r = -0.36, P = 0.003 and r = -0.30, P = 0.02, respectively), whereas the percentage of serum salivary amylase in total serum amylase was positively correlated with blood glucose at 30 and 45 min after starch loading (r = 0.38, P = 0.004 and r = 0.27, P = 0.04, respectively). The level of serum total amylase, but not AMY1 CNV, was correlated inversely with BMI (r = -0.29, P = 0.02). Logistic regression analysis showed that low AMY1 CNV (4 - 7) was significantly associated with an HbA1c of ≥ 5.4% (34 mmol/mol) even after adjustment for age, BMI and energy consumption, compared with high AMY1 CNV (8 - 14).

CONCLUSIONS

Although a higher percentage of serum salivary amylase was associated with higher levels of blood glucose at the early stage after starch loading, low AMY1 CNV was associated with chronic unfavorable glucose metabolism in healthy non-obese young women in Japan.

Low serum amylase, lipase, and trypsin as biomarkers of metabolic disorders: A systematic review and meta-analysis

AIMS

While there is plentiful evidence on elevated serum levels of amylase, lipase, and trypsin in acute illness, low serum levels of these digestive enzymes have been studied infrequently. The aim was to systematically review published studies on the relationship between low serum levels of amylase, lipase, or trypsin and metabolic disorders.

METHODS

The search was conducted in MEDLINE and Scopus databases. Studies in humans were included if they reported on the association between serum levels of amylase, lipase, or trypsin within normal range and metabolic disorders. Random-effects meta-analysis was conducted.

RESULTS

A total of 20 studies encompassing 20,916 participants were included. Compared with healthy individuals, individuals with type 2 diabetes mellitus (mean difference = -5.3; p < 0.001), metabolic syndrome (mean difference = -5.1; p < 0.001), and overweight/obesity (mean difference = -0.8; p = 0.02) had significantly lower serum levels of amylase. Both individuals with type 1 diabetes mellitus (mean difference = -1.8; p < 0.001) and type 2 diabetes mellitus (mean difference = -0.8; p < 0.001) had significantly lower serum levels of lipase compared with healthy individuals. Data on serum trypsin were not suitable for meta-analysis. In the pooled analysis, individuals with type 2 diabetes mellitus had 3.1-times lower serum levels of amylase, 2.9-times lower serum levels of lipase, and 2.5-times lower serum levels of trypsin levels than the upper limits of normal for the three digestive enzymes.

CONCLUSION

Low serum levels of amylase and lipase are significantly associated with type 2 diabetes mellitus, type 1 diabetes mellitus, excess adiposity, and metabolic syndrome. The role of digestive enzymes in the pathogenesis of metabolic disorders warrants further investigations.