Metabolic Syndrome and Incident Asthma in Chinese Adults: An Open Cohort Study

Association between Serum Lipids and Asthma in Adults-A Systematic Review

(1) Background: Asthma is a syndrome found in both adults and children, characterized by airflow obstruction caused by the inflammation of the airways. In recent years, an increasing number of studies have found that lipid metabolism influences both the development and symptomatology of asthma. Lipid metabolism plays an important role both in the occurrence of exacerbations and in the reduction of lung inflammation. Our study aimed to identify any type of association between patients diagnosed with asthma and their serum lipids, including HDL-cholesterol, LDL-cholesterol, total cholesterol, and triglycerides in adults. (2) Methods: To find articles for our review, we searched two platforms: PubMed and Google Scholar. A total of 309 articles from two platforms were analyzed. Finally, 12 papers were selected from the initial pool of identified articles. (3) Results: The positive correlation between triglycerides, total cholesterol, low-density lipoprotein-cholesterol (LDL-cholesterol), and asthma has been demonstrated in several studies. Moreover, it appears that there is an association between biomarkers of type 2 inflammation and HDL and serum triglycerides in people with atopic status. Regarding the nutrition of asthmatic patients, the greatest impact on the development of the disease seems to be the consumption of fruit and vegetables. Several studies show that a predominantly vegan diet is associated with better control of the disease and a decrease in the number of pro-inflammatory cytokines. (4) Conclusions: Studies show a positive correlation between total cholesterol, triglyceride, and LDL-cholesterol levels and asthma and a negative correlation between HDL-cholesterol and asthma. Increased cholesterol values would lead to the stimulation of pro-inflammatory processes and the secretion of cytokines involved in these processes. The most successful diets for asthma patients seem to be those in which the consumption of fruit, vegetables, and high-fiber foods is increased because all of these food groups are rich in vitamins, antioxidants, and minerals.

Evaluation of elevated plasma fatty acids as relevant factors for adult-onset asthma: The Nagahama Study

BACKGROUND

Obesity and increased body mass index (BMI) are the known risk factors for adult-onset asthma. Serum free fatty acid (FFA) and other blood lipid levels are generally elevated in patients with obesity and may be involved in the onset of asthma. However, it remains largely unknown. This study aimed to elucidate the relationship between plasma fatty acids and new-onset asthma.

METHODS

This community-based Nagahama Study in Japan enrolled 9804 residents. We conducted self-reporting questionnaires, lung function tests, and blood tests at baseline and 5 years later as follow-up. At the follow-up, plasma fatty acids were measured using gas chromatography-mass spectrometry. Body composition analysis was also measured at the follow-up. The associations between fatty acids and new-onset asthma were evaluated using a multifaceted approach, including targeted partial least squares discriminant analysis (PLS-DA).

RESULTS

In PLS-DA for new-onset asthma, palmitoleic acid was identified as the fatty acid most associated with asthma onset. In the multivariable analysis, higher levels of FFA, palmitoleic acid, or oleic acid were significantly associated with new-onset asthma, independent of other confounding factors. The high body fat percentage itself was not the relevant factor, but showed a positive interaction with plasma palmitoleic acid for new-onset asthma. When stratified by gender, the impacts of higher levels of FFA or palmitoleic acid on new-onset asthma remained significant in females, but not in males.

CONCLUSIONS

Elevated levels of plasma fatty acids, particularly palmitoleic acid, may be a relevant factor for new-onset asthma.

The association between body mass index, abdominal fatness, and weight change and the risk of adult asthma: a systematic review and meta-analysis of cohort studies

Obesity has been associated with increased risk of adult asthma, however, not all studies have found a clear association between overweight and the incidence of asthma, and data on other adiposity measures have been limited. Hence, we aimed to summarize evidence on association between adiposity and adult asthma. Relevant studies were retrieved through searches conducted in PubMed, and EMBASE up to March 2021. A total of sixteen studies (63,952 cases and 1,161,169 participants) were included in the quantitative synthesis. The summary RR was 1.32 (95% CI 1.21-1.44, I² = 94.6%, p_{heterogeneity}< 0.0001, n = 13) per 5 kg/m² increase in BMI, 1.26 (95% CI 1.09-1.46, I² = 88.6%, p_{heterogeneity} < 0.0001, n = 5) per 10 cm increase in waist circumference and 1.33 (95% CI 1.22-1.44, I² = 62.3%, p_{heterogeneity}= 0.05, n = 4) per 10 kg increase in weight gain. Although the test for nonlinearity was significant for BMI (p_nonlinearity < 0.00001), weight change (p_nonlinearity = 0.002), and waist circumference (p_nonlinearity = 0.02), there was a clear dose-response relationship between higher levels of adiposity and asthma risk. The magnitude of the associations and the consistency of the results across studies and adiposity measures provide strong evidence that overweight and obesity, waist circumference and weight gain increases asthma risk. These findings support policies to curb the global epidemic of overweight and obesity.

Association of weight-adjusted-waist index with asthma prevalence and the age of first asthma onset in United States adults

OBJECTIVE

The objective of this study was to assess whether the weight-adjusted-waist index(WWI) is associated with the prevalence of asthma and age when first asthma onset appears in US adults.

METHODS

For analysis we selected participants from the National Health and Nutrition Examination Survey(NHANES)database between 2001 and 2018. A dose-response curve was calculated using logistic regression,subgroup analysis,and a dose-response curve.

RESULTS

The study included 44480 people over the age of 20,including 6061 reported with asthma, and the increase in asthma prevalence was 15% associated with each unit increase in the WWI, after adjusting for all confounders(odds ratio(OR)=1.15,95% CI:1.11,1.20). The sensitivity analysis was performed by trichotomizing the WWI, and compared to the lowest tertile, the highest tertile WWI group displayed a 29% increase in asthma prevalence(OR=1.29,95% CI:1.19,1.40). A nonlinear correlation was found between the WWI index and the risk of asthma onset, with a threshold saturation effect indicating an inflection point of 10.53 (log-likelihood ratio test, P<0.05), as well as a positive linear correlation with age at first asthma onset.

CONCLUSIONS

A higher WWI index was associated with an increased prevalence of asthma and an older age of first asthma onset.

An Elevated METS-IR Index Is Associated With Higher Asthma Morbidity and Earlier Age of First Asthma in US Adults: Results Based on a Cross-Sectional Study

OBJECTIVE

The purpose of this study was to evaluate whether there is a correlation between the METS-IR index and asthma among Americans.

METHODS

In an attempt to establish the relationship between the METS-IR index and asthma prevalence and age at first onset of asthma, we conducted a logistic regression analysis, subgroup analysis, and dose-response curve analysis using the National Health and Nutrition Examination Survey (NHANES) database.

RESULTS

In model 3, each unit increase in METS-IR index led to 1.5% increase in asthma prevalence (OR= 1.015, 95% CI: 1.012, 1.018) and an earlier age of onset of asthma by 0.057years (β= -0.057, 95% CI: -0.112, -0.002).Stratified analysis determined that an increase in METS-IR index was associated with asthma prevalence in almost all subgroups, except in the group where it was not known whether a blood relative had asthma, and a positive linear relationship was found between METS-IR index and asthma prevalence, as well as a linear negative relationship with age at asthma onset.

CONCLUSION

Despite the fact that a direct causal relationship cannot be demonstrated, a higher METS-IR index is positively related to asthma prevalence and correspondingly may result in asthma onset at younger ages.