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21st September 2021
Regular intake of nuts has been associated with a 15% lower risk of cardiovascular disease and a 23% lower risk of cardiovascular mortality. This reduction in risk is probably due to a reduction in low-density cholesterol (LDL-C) levels with one pooled analysis of 25 intervention trials finding that a mean daily intake of 67g of nuts produced a 7.4% mean reduction in LDL-C levels. However, none of the 25 trials lasted longer than 8 weeks and have not examined the effect of nuts on different LDL sub-fractions. In trying to establish the effect of both daily nut consumption and any differences in the effect on low-density lipoprotein levels, a team from the Lipid Clinic, Endocrinology and Nutrition Services, Villarroel, Barcelona, Spain, decided to explore these effects in a randomised trial. The team established the Walnuts and Healthy Aging (WAHA) trial which ran from 2012 to 2014 and was designed to examine the impact of bioactive compounds, such as n-3 fatty acids (found in walnuts) on both cognitive function and retinal health. Free-living participants were randomised to receive 30 – 60g/day of walnuts, which were delivered to the intervention group individuals, or to abstain from the nuts for the two years of the trial. One of the secondary outcomes of the original trial was changes in lipoprotein levels. Together with fasting glucose, lipoprotein levels were were measured at baseline at after 2 years. In addition, given that those eating walnuts were consuming more fat and thus likely to experience weight gain, this was also measured and compared with the baseline reading.
There were 636 participants with a mean age of 69 years (67% female) who completed the two-year trial. The mean baseline LDL-C and triglyceride levels were 117 and 105 mg/dL respectively. Among those taking walnuts, mean total cholesterol levels decreased by 4.4%
(-8.5 mg/dL, 95% CI -11.2 to -5.4), LDL-C by 3.6% (-4.3, 95% CI -6.6 to -1.6) and intermediate-density lipoprotein cholesterol by 16.8% (-1.3, 95% CI -1.50 to -1.0). Interestingly, levels of both triglycerides and high-density lipoprotein levels were unchanged. Weight changes in the walnut group were negligible at 0.06kg (95% CI -0.32 to 0.44). Furthermore, LDL-C reductions were higher for men than women (7.9% vs 2.6%, men vs women). In addition, there were also reductions in total LDL particles and small LDL particle number by 4.3% and 6.1% respectively.
The authors suggest that the reduction is LDL-C cholesterol at 4.3 mg/dL was modest and concluded that daily walnut intake may be useful way to improve cardiovascular risk.
Rajaram S et al. Effects of Walnut Consumption for 2 Years on Lipoprotein Subclasses Among Healthy Elders. Findings From the WAHA Randomized Controlled Trial. Circulation 2021.
23rd July 2021
Elevated levels of low-density lipoprotein cholesterol (LDL-C) leads to the development of atherosclerosis and is a risk factor for cardiovascular disease. Some evidence suggests an association between childhood obesity and the subsequent risk of biochemical abnormalities in adults. Nevertheless, there is a lack of longitudinal data linking the presence of childhood cardiovascular risk factors with adult disease. Furthermore, little is known about the extent to which risk factors such as LDL-C levels vary during childhood and how this might contribute towards atherosclerosis and adverse cardiovascular outcomes in adult life. A better understanding the childhood trajectories of LDL-C cholesterol could lead to improved preventative strategies. In trying to shed more light on this topic, a team from the Division of General Medicine, Columbia University, Irving Medical Centre, New York, turned to data available in the International Childhood Cardiovascular Cohort (i3C) Consortium. While children virtually never experience adverse cardiovascular events, the i3C is the first longitudinal cohort study designed to locate adults with detailed and repeated childhood biological, and physical measurements and includes over 10,000 individuals from several countries. The Irving Medical Centre team used data from i3C individuals who had at least one LDL-C measurement between the ages of 3 and 17 years of age and extracted demographic and body mass index information from these participants. The team considered LDL-C levels greater than 160mg/dl (4.14mmol/l) as consistent with probable familial hypercholesterolaemia (FH) and used the more stringent criteria of an LDL-C of greater than 160mg/dl on at least two occasions and a level of LDL-C of 190mg/dl or greater as a threshold for FH. In order to examine LDL-C trajectories during childhood, the team fitted a linear model of LDL-C against age, adjusting for sex, ethnicity and body mass index.
A total of 15,045 children with a mean age of 9.9 years (48.7% male) were included in the analysis. Overall, 2.8% of children had an LDL-C greater than 160mg/dl and 0.6% had values exceeding 190mg/dL. Using the more stringent criteria, 1% of children had elevated LDL-C levels (> 160mg/dL) on two occasions and 0.3%, levels above 190mg/dl, consistent with FH. Using the linear model it could be seen that mean LDL-C cholesterol levels increased from age 3 to 10 years, decreased from age 10 to 15 but then increased again to reach adult levels. LDL-C levels were consistently and significantly higher in female children and those of Black ethnicity or with a higher body mass index.
In a discussion of their findings, the authors noted how LDL-C levels peaked between ages 9 and 11 and that these levels were comparable to those aged 18 years. This, the authors suggested, highlighted the importance of childhood lipid screening from as early as 9 years of age.
Zhang Y et al. Low-Density Lipoprotein Cholesterol Trajectories and Prevalence of High Low-Density Lipoprotein Cholesterol Consistent with Heterozygous Familial Hypercholesterolemia in US Children. JAMA Pediatr 2021