**2. Differences of plasma levels of fatty acids between Japanese and American old men**

#### **2.1 Materials and methods**

#### *2.1.1 Participants*

In Japan, we recruited 44 male volunteers older than 50. They were friends and family members of the research team for this study [33, 34]. Exclusion criteria included the use of medications to treat diabetes, hyperlipidemia, hypertension, and/or cardiovascular disease (CVD). Smokers were also excluded. The 76 US men were participants in the Chicago Area Sleep Study, a prospective cohort study to examine risk factors for the development of sleep disorders [35]. This cohort excluded men with known sleep disturbances but did not exclude for the chronic conditions excluded in the Japanese cohort. We collected blood samples after an overnight fast, and plasma was isolated for fatty acid analysis. We obtained an informed consent prior to conducting the protocol which had been approved by the Ethical Committee of Showa Women's University and Saiseikai Shibuya Satellite Clinic. The Chicago Area Sleep Study was approved by the Northwestern University Institutional Review Board.

#### **2.2 Analyses of plasma samples**

Fatty acids levels were measured in plasma obtained from ethylenediamine tetraacetic acid anticoagulated blood samples. Samples were frozen at −80°C until analyzed at Omegaquant, LLC (Sioux Falls, SD, USA). After thawing, an aliquot of plasma was combined (1.40 parts) with the methylating mixture (boron trifluoride in methanol [14%], toluene, and methanol [35/30/35, vv]), shaken at 100°C for 45 min. After cooling, 40 parts of both hexane and distilled water were added. After briefly vortexing, the samples were spun to separate layers, and an aliquot of the hexane layer that contained the fatty acid methyl esters was analyzed by gas chromatography as previously described.

#### **2.3 Statistical analysis**

Student's t test was used for the comparison of two groups, and p < 0.05 was considered as significant difference. Results are expressed as mean ± SD. Spearman's correlation tests were used to examine statistical significance.

**105**

**Table 1.**

**Figure 5.**

*Profiles of plasma levels of fatty acids of Japanese and American old men.*

*Backgrounds of various parameters of healthy old men in Japan and US.*

Age 62.4 ± 9.6 57.5 ± 4.3 Height (m) 1.68 ± 0.07 1.70 ± 0.1 Weight (kg) 68.8 ± 10.9 74.4 ± 12.1 Body mass index (BMI) 24.3 ± 3.2 25.3 ± 3.4 Total cholesterol (mg/dL) 209.9 ± 32.3 185 ± 33.5 Triglyceride (mg/dL) 126.4 ± 81.3 118.0 ± 62.8 HDL-C (mg/dL) 60.9 ± 16.6 54.0 ± 15.7 LDL-C (mg/dL) 123.8 ± 30.2 107.0 ± 29.6 Fasting blood glucose (mg/dL) 91.7 ± 16.3 97 ± 22.3

*Roles of Trans and ω Fatty Acids in Health; Special References to Their Differences…*

The ages of the two cohorts was reasonably similar (Japan, 61 ± 10 and US, 57 ± 5 years), as were the body mass indexes (24.9 ± 3.7 vs. 25.1 ± 3.4 kg/m2

Of the fatty acids that constituted at least 1% of the total in either cohorts, those that are significantly higher in Japanese men than US men were as follows: palmitic, palmitoleic, arachidic, EPA, and DHA. Those that were lower in the Japanese men were as follows: linoleic acid (LA), dihomo-gamma linolenic acid (DGLA), and AA (**Table 1**).

) (**Figure 5**).

**Japanese (n = 44) American (n = 76)**

*DOI: http://dx.doi.org/10.5772/intechopen.89551*

**3. Results**

*Roles of Trans and ω Fatty Acids in Health; Special References to Their Differences… DOI: http://dx.doi.org/10.5772/intechopen.89551*
