A Randomized Trial of ω-3 Fatty Acid Supplementation and Circulating Lipoprotein Subclasses in Healthy Older Adults

Toward Absolute Quantification of Soluble Proteins via Proton Nuclear Magnetic Resonance Spectroscopy: Total Protein Concentration in Blood Plasma

For absolute protein quantification using nuclear magnetic resonance (NMR) spectroscopy, we considered proteins as homopolymers and effective amino acid (AA) residues (AAREff) as monomer units. For diverse classes of proteins, we determined the AAREff molecular weight as 111.5 ± 3.2 Da and the number of hydrogens per AA as 7.8 ± 0.2. Their ratio of 14.3 ± 0.3 (g/LP)/(mol/LH) remains constant across various protein classes and is equivalent to Kjeldahl's nitrogen-to-protein conversion constant of 5.78 ± 0.29 gN/gP. By analogy to the Kjeldahl method, we suggest that the total integral of a 1H NMR solution protein spectrum could be used for total protein quantification. We synthesized low-resolution protein spectra from the weighted sums of individual AA spectra and compared them with experimental spectra. In the methyl region, the ratio of the protein mass to the total number of protons in the synthetic spectra (corrected for the chemical shift mismatch) was ∼1 (mg/mL)/mM, which agrees with an earlier reported experimental ratio for urine (1.05 ± 0.06 (mg/mL)/mM). For human blood plasma, in the methyl region, we found empirical ratios of 1.115 ± 0.006 (mg/mL)/mM (using 96 patient samples) and 1.121 ± 0.011 (mg/mL)/mM for the NIST plasma standard. This numerical agreement points to universal conversion constants, i.e., protein mixtures with unknown compositions could be quantified without the need for calibration standards by measuring the millimolar proton concentration within the methyl region of the NMR spectrum using the same conversion constant.

A Life-Stage Approach to Precision Nutrition: A Narrative Review

The concept of precision nutrition highlights the customization of nutrition to specific needs, emphasizing that a one-size-fits-all approach is not sufficient for either optimal nutrition or optimal health. Precision nutrition encompasses a range of factors, from broad strata of age and sex categories to personal characteristics such as lifestyle to an individual's unique genotype. This breadth of scope requires us to consider how precision nutrition can be implemented in an inclusive and appropriate way for individuals and groups within real-life populations. In this narrative review, we explore the potential of precision nutrition through a life-stage approach that emphasizes age- and gender-specific nutritional needs as these change across the lifespan. Focusing on adult life stages, we delineated trends in age-related conditions and health needs among Korean adults based on national-level survey data (KNHANES 2019-2021). We also reviewed the intake of nutrients associated with these health needs to better understand how life-stage guided approaches to nutrition and supplementation could support optimal health. Looking beyond preventing deficiency or disease, we discuss how tailored supplementation of essential vitamins, minerals, and certain bioactive substances could promote healthy functioning. Finally, we discuss the complexities and challenges of developing multivitamin/multimineral supplements (MVMS) to support life-stage appropriate nutrition while maximizing adherence. Future prospects include leveraging advancements in intelligent technologies and dietary assessments for tracking nutrient intake and health indicators and using these to optimize MVMS formulations in ways that are sensitive to a person's needs and priorities/preferences at different life stages. By adopting a life-stage guided approach to nutrition, we can better support health and well-being across the lifespan.

High-Density Lipoprotein Subclasses and Their Role in the Prevention and Treatment of Cardiovascular Disease: A Narrative Review

The association between high-density lipoprotein cholesterol (HDL-C) and cardiovascular disease (CVD) is controversial. HDL-C is one content type of high-density lipoprotein (HDL). HDL consists of diverse proteins and lipids and can be classified into different subclasses based on size, shape, charge, and density, and can change dynamically in disease states. Therefore, HDL-C levels alone cannot represent HDLs' cardioprotective role. In this review, we summarized the methods for separating HDL subclasses, the studies on the association between HDL subclasses and cardiovascular risk (CVR), and the impact of lipid-modifying medications and nonpharmacological approaches (exercise training, dietary omega fatty acids, and low-density lipoprotein apheresis) on HDL subclasses. As HDL is a natural nanoplatform, recombinant HDLs (rHDLs) have been used as a delivery system in vivo by loading small interfering RNA, drugs, contrast agents, etc. Therefore, we further reviewed the HDL subclasses used in rHDLs and their advantages and disadvantages. This review would provide recommendations and guidance for future studies on HDL subclasses' cardioprotective roles.

Association of marine PUFAs intakes with cardiovascular disease, all-cause mortality, and cardiovascular mortality in American adult male patients with dyslipidemia: the U.S. National Health and Nutrition Examination Survey, 2001 to 2016

BACKGROUND

The relationship between marine polyunsaturated fatty acid (PUFA) intake and cardiovascular disease and mortality in dyslipidemic patients is unclear. Men with dyslipidemia have a higher risk of cardiovascular disease than women, and PUFA supplementation may be more beneficial in men.

OBJECTIVE

The purpose of this study was to assess the relationship between different types of marine polyunsaturated fatty acids intakes and cardiovascular disease, all-cause mortality, and cardiovascular mortality in adult U.S. males with dyslipidemia.

METHODS

The study ultimately included 11,848 adult men with dyslipidemia who were screened from the National Health and Nutrition Examination Survey (NHANES) between 2001 and 2016. This was linked to the 2019 National Death Index (NDI) records to establish a prospective cohort. In the study, a logistic regression model was established to assess the relationship between PUFA intake and prevalent CVD, and a Cox proportional hazards regression model was established to assess the relationship between PUFA intake and death.

RESULTS

In the fully adjusted models, compared with participants in the lowest tertile, participants with the highest DPA intake were associated with a lower risk of CVD (CVD: OR = 0.71, 95%CI: 0.55, 0.91; angina: OR = 0.54, 95%CI: 0.38, 0.79; stroke: OR = 0.62, 95%CI: 0.43, 0.89), but not with three subtypes of congestive heart failure, coronary heart disease, and myocardial infarction. And the highest tertile level of DPA intake can reduce all-cause mortality (HR = 0.77, 95%CI: 0.64, 0.91) and CVD mortality (HR = 0.68, 95%CI: 0.52, 0.90).

CONCLUSIONS

Cardiovascular disease risk, all-cause mortality, and CVD mortality were inversely associated with dietary DPA intake but not EPA and DHA intakes in U.S. male participants with dyslipidemia.

Sex-specific responses in glucose-insulin homeostasis and lipoprotein-lipid components after high-dose supplementation with marine n-3 PUFAs in abdominal obesity: a randomized double-blind crossover study

Background

Clinical studies on effects of marine-derived omega-3 (n-3) polyunsaturated fatty acids (PUFAs), mainly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and the plant-derived omega-6 (n-6) PUFA linoleic acid (LA) on lipoprotein-lipid components and glucose-insulin homeostasis have shown conflicting results, which may partly be explained by differential responses in females and males. However, we have lacked data on sexual dimorphism in the response of cardiometabolic risk markers following increased consumption of n-3 or n-6 PUFAs.

Objective

To explore sex-specific responses after n-3 (EPA + DHA) or n-6 (LA) PUFA supplementation on circulating lipoprotein subfractions, standard lipids, apolipoproteins, fatty acids in red blood cell membranes, and markers of glycemic control/insulin sensitivity among people with abdominal obesity.

Methods

This was a randomized double-blind crossover study with two 7-week intervention periods separated by a 9-week washout phase. Females (n = 16) were supplemented with 3 g/d of EPA + DHA (fish oil) or 15 g/d of LA (safflower oil), while males (n = 23) received a dose of 4 g/d of EPA + DHA or 20 g/d of LA. In fasting blood samples, we measured lipoprotein particle subclasses, standard lipids, apolipoproteins, fatty acid profiles, and markers of glycemic control/insulin sensitivity.

Results

The between-sex difference in relative change scores was significant after n-3 for total high-density lipoproteins (females/males: -11%*/-3.3%, p = 0.036; *: significant within-sex change), high-density lipoprotein particle size (+2.1%*/-0.1%, p = 0.045), and arachidonic acid (-8.3%*/-12%*, p = 0.012), and after n-6 for total (+37%*/+2.1%, p = 0.041) and small very-low-density lipoproteins (+97%*/+14%, p = 0.021), and lipoprotein (a) (-16%*/+0.1%, p = 0.028). Circulating markers of glucose-insulin homeostasis differed significantly after n-3 for glucose (females/males: -2.1%/+3.9%*, p = 0.029), insulin (-31%*/+16%, p < 0.001), insulin C-peptide (-12%*/+13%*, p = 0.001), homeostasis model assessment of insulin resistance index 2 (-12%*/+14%*, p = 0.001) and insulin sensitivity index 2 (+14%*/-12%*, p = 0.001), and quantitative insulin sensitivity check index (+4.9%*/-3.4%*, p < 0.001).

Conclusion

We found sex-specific responses after high-dose n-3 (but not n-6) supplementation in circulating markers of glycemic control/insulin sensitivity, which improved in females but worsened in males. This may partly be related to the sex differences we observed in several components of the lipoprotein-lipid profile following the n-3 intervention.

Clinical trial registration

https://clinicaltrials.gov/, identifier [NCT02647333].

A Randomized Trial of the Effects of Dietary n3-PUFAs on Skeletal Muscle Function and Acute Exercise Response in Healthy Older Adults

Skeletal muscle is critical for maintaining mobility, independence, and metabolic health in older adults. However, a common feature of aging is the progressive loss of skeletal muscle mass and function, which is often accompanied by mitochondrial impairments, oxidative stress, and insulin resistance. Exercise improves muscle strength, mitochondrial health, and cardiorespiratory fitness, but older adults often exhibit attenuated anabolic responses to acute exercise. Chronic inflammation associated with aging may contribute to this "anabolic resistance" and therapeutic interventions that target inflammation may improve exercise responsiveness. To this end, we conducted a randomized controlled trial to determine the effect of 6 months of dietary omega-3 polyunsaturated fatty acids (n3-PUFA) supplementation on skeletal muscle function (mass, strength), mitochondrial physiology (respiration, ATP production, ROS generation), and acute exercise responsiveness at the level of the muscle (fractional synthesis rate) and the whole-body (amino acid kinetics) in healthy older adults. When compared with a corn oil placebo (n = 33; 71.5 ± 4.8 years), older adults treated with 4 g/day n3-PUFA (n = 30; 71.4 ± 4.5 years) exhibited modest but significant increases in muscle strength (3.1 ± 14.7% increase in placebo vs. 7.5 ± 14.1% increase in n3-PUFA; p = 0.039). These improvements in muscle strength with n3-PUFA supplementation occurred in the absence of any effects on mitochondrial function and a minor attenuation of the acute response to exercise compared to placebo. Together, these data suggest modest benefits of dietary n3-PUFAs to muscle function in healthy older adults. Future studies may elucidate whether n3-PUFA supplementation improves the exercise response in elderly individuals with co-morbidities, such as chronic inflammatory disease or sarcopenia.