Summary of available data for cholesterol in foods and methods for its determination

Trends in Serum Total Cholesterol and High Total Cholesterol Prevalence Among Royal Thai Army Personnel in Thailand, 2017-2022

INTRODUCTION

High total cholesterol (TC) is a robust-documented risk factor for atherosclerosis cardiovascular diseases. Approximately one-fourth (23.5%) of Thai civilians had high TC. However, the information on high TC among the Royal Thai Army (RTA) personnel is limited.

AIM

The study aimed to identify the trends in serum TC and high TC prevalence among RTA personnel from 2017 to 2022.

METHODS

A serial cross-sectional study from 2017 to 2022 was conducted. A total of 318,353 active-duty RTA personnel aged 35-60 years were included in the study. High TC was defined as fasting TC ≥ 240 mg/dL. A multivariable log-binomial regression analysis was performed to investigate factors associated with high TC.

RESULTS

The overall age- and sex-adjusted high TC prevalence was 26.3% in 2017 and dropped to 22.9% in 2020; then, it increased to 26.4% in 2022 (p for quadratic trend < 0.001). Younger-aged RTA personnel have significantly rising trends in sex-adjusted high TC prevalence over 6 years. In the south, the age- and sex-adjusted high TC prevalence was 24.4% in 2017 and substantially rose to 33.6% in 2022 (p for quadratic trend < 0.001). Meanwhile, in the northeast, it rose by 3.6% over 6 years. High body mass index, high blood pressure, and hyperglycemia were associated with high TC prevalence among this population.

CONCLUSION

High TC was a common essential health issue among RTA personnel. Rising trends in mean serum TC and high TC prevalence from 2017 to 2022 were discovered, especially in younger participants and those residing in the south and northeast.

Presence of Cholesterol in Non-Animal Organisms: Identification and Quantification of Cholesterol in Crude Seed Oil from Perilla frutescens and Dehydrated Pyropia tenera

Studies have reported that cholesterol, a molecule found mainly in animals, is also present in some plants and algae. This study aimed to determine whether cholesterol exists in three dehydrated algae species, namely, Pyropia tenera, Saccharina japonica, and Undaria pinnatifida, and in one plant species, namely, Perilla frutescens (four perilla seed oil samples were analyzed). These species were chosen for investigation because they are common ingredients in East Asian cuisine. Gas chromatography-flame ionization detection (GC-FID) analysis found that cholesterol was present in P. tenera (14.6 mg/100 g) and in all four perilla seed oil samples (0.3–0.5 mg/100 g). High-performance liquid chromatography with evaporative light-scattering detection (HPLC-ELSD) also demonstrated that cholesterol was present in P. tenera (14.2 mg/100 g) and allowed the separation of cholesterol from its isomer lathosterol. However, cholesterol could not be detected by HPLC-ELSD in the perilla seed oil samples, most likely because it is only present in trace amounts. Moreover, liquid chromatography-tandem mass spectrometry (LC-MS/MS) confirmed the presence of cholesterol in both P. tenera and perilla seed oil. MRM results further suggested that lathosterol (a precursor of cholesterol) was present in P. tenera.

Dietary patterns, food groups, and nutrients as predictors of plasma choline and betaine in middle-aged and elderly men and women

BACKGROUND

Choline and betaine are linked to phospholipid and one-carbon metabolism. Blood concentrations or dietary intake of these quaternary amines have been related to the risk of chronic diseases, including cardiovascular disease and the metabolic syndrome.

OBJECTIVE

We aimed to determine dietary predictors of plasma choline and betaine among middle-aged and elderly subjects recruited from an area without folic acid fortification.

DESIGN

This is a population-based study of 5812 men and women aged 47-49 and 71-74 y, within the Hordaland Health Study cohort. Plasma concentrations per increasing quartile of intake of foods, beverages, and nutrients were assessed by multiple linear regression analysis, and dietary patterns were assessed by factor analysis.

RESULTS

Plasma choline was predicted by egg consumption (0.16 micromol/L; P < 0.0001) and cholesterol intake (0.16 micromol/L; P < 0.0001), and betaine was predicted by consumption of high-fiber bread (0.65 micromol/L; P < 0.0001); high-fat dairy products (-0.70 micromol/L; P < 0.0001); complex carbohydrates, fiber, folate, and thiamine (0.66-1.44 micromol/L; P <or= 0.0002 for all); and total energy (0.45 micromol/L; P = 0.004). Plasma choline was not significantly associated with any identified dietary patterns, whereas betaine was negatively associated with a Western dietary pattern with a high loading for meat, pizza, sugar, and fat (P < 0.0001).

CONCLUSION

In this population of middle-aged and elderly men and women, recruited from an area with relatively low folate intake, neither plasma choline nor betaine was positively associated with consumption of animal products, fruit, or vegetables, but each was positively associated with the intake of specific food items such as eggs (choline) and bread (betaine).

Chromatographic separation of cholesterol in foods

Based on the current literature and on experience gained in the laboratory, a simplified procedure using direct saponification (0.4 M potassium hydroxide in ethanol and heating at 60 degrees C for 1 h) is the most appropriate method for the determination of total cholesterol in foods. Extraction of the unsaponifiable matter with hexane is efficient and no extra clean-up is required before quantification. An internal standard, 5 alpha-cholestane or epicoprostanol, should be added to the sample prior to saponification and, together with reference standards, carried through the entire procedure to ensure accurate results. A significant improvement in cholesterol methodology has been achieved by decreasing the sample size and performing all the sample preparation steps in a single tube. The method has the advantages of elimination of an initial solvent extraction for total lipids and errors resulting from multiple extractions, transfers, filtration and wash steps after saponification. The resulting hexane extract, which contains a variety of sterols and fat soluble vitamins, requires an efficient capillary column for complete resolution of cholesterol from the other compounds present. The development of fused-silica capillary columns using cross-linked and bonded liquid phases has provided high thermal stability, inertness and separation efficiency and, together with automated cold on-column gas chromatographic injection systems, has resulted in reproducible cholesterol determinations in either underivatized or derivatized form. If free cholesterol and its esters need to be determined separately, they are initially extracted with other lipids with chloroform-methanol followed by their separation by column or thin-layer chromatography and subsequently analysed by gas or liquid chromatography. Although capillary gas chromatography offers superior efficiency in separation, the inherent benefits of liquid chromatography makes it a potential alternative. Isotope dilution mass spectrometry has been widely accepted as a reliable analytical method for highly accurate determination of cholesterol in serum and several definitive methods have been reported. The combination of capillary gas chromatography with mass spectrometry has become an excellent approach for the determination of cholesterol in complex mixtures of sterols and tocopherols, providing high resolution with positive identification. When used to determine cholesterol in multi-component foods, spectrophotometric methods have been documented to overestimate significantly the amount of cholesterol owing to the presence of other interfering substances. A re-evaluation of food products should be undertaken using the more specific chromatographic methods to accumulate data that will more accurately reflect the true cholesterol content.

Quantification of oxysterols in Dutch foods: egg products and mixed diets

A sensitive and specific method is described for quantifying various cholesterol oxidation products in foodstuffs, including 7 beta-hydroxycholesterol, cholesterol-alpha-epoxide, cholestane-triol, 7-ketocholesterol and 25-hydroxycholesterol. A chloroform-methanol extract of the food was fractionated over two successive silica columns. Two fractions containing different classes of oxysterols were then analyzed as trimethylsilyl derivatives by capillary gas liquid chromatography, using on-column injection and a temperature gradient from 70 to 200 degrees C. The detection limit was about 0.5 microgram/g dry weight for egg yolk powder. Fresh egg yolk contained only 1.2 micrograms/g of total oxides per g dry weight, showing that artifactual oxidation during the procedure was minimal. Recovery of 5 pure oxysterols added to egg yolk at levels of 6.5 and 10 micrograms/g was between 93 and 102%. In commercial egg yolk and whole egg powder stored for one year, total amounts of oxysterols ranging from 21 to 137 micrograms/g dry weight were found. In duplicates of mixed Dutch diets, total amounts ranged from 3.6 to 6.2 micrograms/g dry weight. Duplicates containing mostly fried and baked foods did not have higher levels than duplicates in which foods had been prepared by boiling or left raw. We conclude that a normal mixed diet provides only minor amounts of cholesterol oxidation products.

Distribution of cholesterol in milk fat fractions

Milk fat was fractionated into liquid (m.p. congruent to 12 degrees C), intermediate (m.p. congruent to 21 degrees C) and solid (m.p. congruent to 39 degrees C) fractions by three different processes--melt crystallization, short-path distillation and supercritical CO2 extraction--and the cholesterol content of these fractions determined. Cholesterol was enriched in the liquid fractions from all three processes, in particular about 80% of the cholesterol being found in the liquid fraction obtained by short-path distillation. The basis of migration of cholesterol into various milk fat fractions was explained by its affinity to various triglycerides (melt crystallization) and by vapour pressure and molecular weight (short-path distillation). It was more complex in the supercritical CO2 extraction process; the interplay of cholesterol affinity toward CO2 and its molar volume, and its vapour pressure enhancement under applied pressure play a role.