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  1. Ng, Tony Kock Wai
    MyJurnal
    A review of the literature indicates that food scientists and health authorities in several countries, especially member countries of the European Union, are still very concerned about the potential health hazards of oxidized products and lipid polymers formed in repeatedly-used deep frying oils. During the frying process at temperatures of 170° – 200°C, steam formed from moisture in the food being fried help volatile products rise to the surface of the frying medium and into the kitchen atmosphere, imparting a mixture of fried-flavours and off-flavours. The non-volatile compounds formed, however, gradually build up in the oil as it is being repeatedly-used for food frying operations. These non-volatiles, primarily “polar compounds” (PC) and to a lesser extent lipid polymers, get absorbed into fried foods and eventually end up in our body system. Available local data suggests that deep-frying oil samples obtained from food hawkers and those produced under simulated deep-frying conditions in the laboratory, are generally safe as they contain PC within safe limits and rarely exceed the upper limit (UL) of 25%. This contrasts with the situation in some European countries where a very high proportion of frying oil samples collected from fast-food restaurants were reported to contain PC exceeding this UL. Appropriately, promotion of Hazard Analysis and Critical Control Points (HACCP) certification and gazetting of food regulations to limit the PC content in frying oils have been introduced in these countries to protect the health of consumers. Meanwhile, simple gadgets/test kits are available commercially to monitor the quality of the frying oil. This would greatly assist kitchen supervisors at restaurants and franchised friedfood outlets to know when best to change a batch of frying oil before the ULs of frying oil quality are breached.
  2. Ng, Tony Kock Wai
    MyJurnal
    Introduction: The content of polar compounds (PC) and polymeric triglycerides build up in fried and recycled/reused oils and therefore, these undesirable components are often used as markers of deterioration in edible oil quality. Expert and authoritative agencies have recommended an upper limit of 25% for PC in fried/reused edible oils; beyond this level the oil is considered unsuitable for human consumption. The safety of recycled or repeatedly-heated oils is still very much a concern of both the health authorities and the general public.
    Objective: The present study evaluates the safety of long-tern consumption of heated vegetable oils containing 25% of PC on growth, effect on major body organs and reproduction outcome, using the Sprague-Dawley rat model.
    Methods: Refined, bleached and deodorised palm olein (PO) and partially hydrogenated soybean oil (HSBO) were repeatedly heated for 5 hours daily with no topping-up at Isoac until a polar compound (PC) content of25% was attained. Refined soybean oil was similarly heated up to 50% PC and used in the positive control diet. All five experimental oils, namely unheated PO (No PC), heated PO (25% PC), unheated HSBO (No PC), heated HSBO (25% PC), and positive control oil (50% PC) were separately incorporated at 30% energy (15% w/w) as the sole dietary fat into nutritionally-adequate purified diets. Each experimental diet was provided ad libitum to a different dietary group comprising 14 male and 20 female Swiss albino rats. After 13 weeks (90 days), 10 males were selected from each group and each male was paired with two females from the same dietary group for the reproductive study. After 4 weeks into the reproductive study (total of 17 weeks on the experimental diets), all 10 males in each group were sacrificed and the usual toxicity tests consisting of blood cell type counts, liver and kidney function tests, and examination (organ-to-body weight ratios and histology) of the liver, kidney, heart and spleen were performed.
    Results: The heated PO and HSBO diets were well-tolerated by the animals. However, these heated test oils inhibited growth marginally (p>0.05), enlarged the liver, kidney and heart, and markedly raised serum alkaline phosphatase (liver function test) compared to the unheated oils (p
  3. Ng, Tony Kock Wai, Jia, Yu Tang, Low, Yip Onn, Yeoh, Loo Zheng Wei Yeoh, Gan, Cai Li
    MyJurnal
    Introduction: Dietary fibre (DF) and fluid intakes
    have been reported elsewhere to reduce the risk
    of constipation. The association of these dietary
    components on Agachand’s Constipation Score (CS)
    was investigated in the present study.

    Methods: A total of 202 Malaysian participants
    comprising 50 adolescents (aged 12.4 ± 5.3 yrs),
    50 adults (aged 46.3 ± 11.3 yrs), 52 women of childbearing
    age (aged 29.1 ± 9.3 yrs) and 50 elderly persons
    (aged 70.0 ± 7.4 yrs) were recruited by convenience
    sampling from five venues - two communities in Cheras,
    one community in Klang, the IMU campus, Bukit Jalil
    and a private secondary school in Klang. All participants
    were interviewed with a previously-evaluated food
    frequency questionnaire (FFQ) and an Agachand’s
    Constipation Score (CS) Questionnaire.

    Results: Mean daily DF intakes were low across all
    age groups with means ranging from 10.0 – 15.6g.
    The percentage of subjects with daily DF intakes below
    the “deficient” cut-off of 20g was alarmingly high;
    80% in adolescents, 45% in adults, 85% in women of
    child-bearing age and 70% in the elderly. About onefifth
    or 20% of subjects in all age groups had CS values
    ≥15 which indicated a problem of constipation.
    Mean daily total fluid consumption (TFC) ranged
    from 2128 – 5490 ml in the four categories of subjects.
    Overall, both daily DF intakes and TFC were negatively
    associated with CS values. This inverse association was
    significant for DF vs CS scores in adolescents (r = -0.500,
    p = 0.001), adults (r = -0.351, p = 0.013), the elderly
    (r = -0.392, p = 0.005) and all subjects combined
    (r = -0.366, p=0.001). For TFC vs CS scores, the
    inverse association was only significant for the elderly
    (r = -0.312, p = 0.027) and all subjects combined
    (r = -0.245, p = 0.001).

    Conclusion: The results of this study support the role
    of dietary fibre intake and TFC in reducing the risk of
    constipation, as well as reinforcing previous data for low
    DF intakes among the Malaysian population.
  4. Voon PT, Ng TK, Lee VK, Nesaretnam K
    Am J Clin Nutr, 2011 Dec;94(6):1451-7.
    PMID: 22030224 DOI: 10.3945/ajcn.111.020107
    BACKGROUND: Dietary fat type is known to modulate the plasma lipid profile, but its effects on plasma homocysteine and inflammatory markers are unclear.

    OBJECTIVE: We investigated the effects of high-protein Malaysian diets prepared with palm olein, coconut oil (CO), or virgin olive oil on plasma homocysteine and selected markers of inflammation and cardiovascular disease (CVD) in healthy adults.

    DESIGN: A randomized-crossover intervention with 3 dietary sequences of 5 wk each was conducted in 45 healthy subjects. The 3 test fats, namely palmitic acid (16:0)-rich palm olein (PO), lauric and myristic acid (12:0 + 14:0)-rich CO, and oleic acid (18:1)-rich virgin olive oil (OO), were incorporated at two-thirds of 30% fat calories into high-protein Malaysian diets.

    RESULTS: No significant differences were observed in the effects of the 3 diets on plasma total homocysteine (tHcy) and the inflammatory markers TNF-α, IL-1β, IL-6, and IL-8, high-sensitivity C-reactive protein, and interferon-γ. Diets prepared with PO and OO had comparable nonhypercholesterolemic effects; the postprandial total cholesterol for both diets and all fasting lipid indexes for the OO diet were significantly lower (P < 0.05) than for the CO diet. Unlike the PO and OO diets, the CO diet was shown to decrease postprandial lipoprotein(a).

    CONCLUSION: Diets that were rich in saturated fatty acids prepared with either PO or CO, and an OO diet that was high in oleic acid, did not alter postprandial or fasting plasma concentrations of tHcy and selected inflammatory markers. This trial was registered at clinicaltrials.gov as NCT00941837.

  5. Voon PT, Lee ST, Ng TKW, Ng YT, Yong XS, Lee VKM, et al.
    Adv Nutr, 2019 Jul 01;10(4):647-659.
    PMID: 31095284 DOI: 10.1093/advances/nmy122
    It is not clear whether a saturated fatty acid-rich palm olein diet has any significant adverse effect on established surrogate lipid markers of cardiovascular disease (CVD) risk. We reviewed the effect of palm olein with other oils on serum lipid in healthy adults. We searched in MEDLINE and CENTRAL: Central Register of Controlled Trials from 1975 to January 2018 for randomized controlled trials of ≥2 wk intervention that compared the effects of palm olein (the liquid fraction of palm oil) with other oils such as coconut oil, lard, canola oil, high-oleic sunflower oil, olive oil, peanut oil, and soybean oil on changes in serum lipids. Nine studies were eligible and were included, with a total of 533 and 542 subjects on palm olein and other dietary oil diets, respectively. We extracted and compared all the data for serum lipids, such as total cholesterol (TC), LDL cholesterol, HDL cholesterol, triglyceride, and TC/HDL cholesterol ratio. When comparing palm olein with other dietary oils, the overall weighted mean differences for TC, LDL cholesterol, HDL cholesterol, triglycerides, and the TC/HDL cholesterol ratio were -0.10 (95% CI: -0.30, 0.10; P = 0.34), -0.06 (95% CI: -0.29,0.16; P = 0.59), 0.02 (95% CI: -0.01, 0.04; P = 0.20), 0.01 (95% CI: -0.05, 0.06; P = 0.85), and -0.15 (95% CI: -0.43, 0.14; P = 0.32), respectively. Overall, there are no significant differences in the effects of palm olein intake on lipoprotein biomarkers (P > 0.05) compared with other dietary oils. However, dietary palm olein was found to have effects comparable to those of other unsaturated dietary oils (monounsaturated fatty acid- and polyunsaturated fatty acid-rich oils) but differed from that of saturated fatty acid-rich oils with respect to the serum lipid profile in healthy adults.
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