Importance of dietary management in treating lipid disorders: soy diets may offer comparable effect as statins
3 February 2004. Related: Side effects, Lipodystrophy and metabolic complications.
Graham McKerrow, HIV i-Base
Studies in the United States and Canada emphasise the importance of dietary management in the treatment of lipid disorders, which can be just as effective as the use of statins.
DJ Jenkins and colleagues at St Michael’s Hospital, Toronto, write in the November 2003 issue of Metabolism that combining a number of foods and food components in a ‘portfolio diet’ can lower low-density lipoprotein-cholesterol (LDL-C) similarly to statins. [1]
Reductions in LDL-C result from diets containing almonds, or diets that are low in saturated fat or high in viscous fibres, soy proteins or plant sterols. The researchers combined all these into a ‘portfolio diet’ to see if they could achieve cholesterol reductions of similar magnitude to those reported in recent statin trials which reduced cardiovascular events.
Twenty-five hyperlipidaemic subjects were divided into two groups. One group (n=13) consumed a portfolio diet low in saturated fat and high in plant sterols, soy protein, viscous fibres and almonds, while the other group consumed a low saturated fat diet based on whole wheat cereals and low-fat dairy foods. LDL-C was reduced by 12.1%+/-2.4% (P<0.001) on the low fat diet and by 35.0% +/-3.1% (P<0.001) on the portfolio diet, which also reduced the ratio of LDL-C to high density lipoprotein –cholesterol (HDL-C) significantly (30.0%+/- 3.5%; P<.001).
The researchers write: “The reduction in LDL-C and the LDL-C:HDL-C ratio were both significantly lower on the portfolio diet than on the control diet (P<.001 and P<.001, respectively). Mean weight loss was similar on test and control diets (1.0kg and 0.9kg, respectively).”
A paper by Jenkins and colleagues in the July 2003 Journal of the American Medical Association (JAMA) reported that intensive dietary therapy may be just as effective in reducing cholesterol levels as the starting dosage of a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (statin) drug. [2] They randomly assigned 55 healthy hyperlipidaemic men and women to receive one of three treatments: a very low saturated fat diet based on whole-grain wheat cereals and low fat dairy foods (control group), the same diet plus lovostatin, 20mg/d (statin group), or a portfolio diet (see above). Based on data from 46 subjects in the four-week study, the authors report that the statin and dietary portfolio treatment groups had approximately 30% reduction in LDL-C compared with an 8% reduction in the control group.
In an editorial in the same issue of JAMA, James W Anderson writes: “These results are potentially important, given the expense, safety concerns, and intolerance related to statin use. Moreover, if confirmed in other rigorous investigations, these findings could have far-reaching implications for a large number of patients with dyslipidaemia; those who are motivated to adopt prudent diets might achieve meaningful lipid reductions without pharmacotherapy.” [3]
The November 2003 issue of the Wellness Letter published by the University of California, Berkeley, commented “the portfolio diet is a good one” but under a section headed ‘Pluses and minuses’, it added: “If you are a vegetarian, the portfolio diet may seem easy; if you are accustomed to eating meat, poultry, fish, and dairy, it could be hard. And fish and low-fat or nonfat dairy products have their own cardiovascular benefits.“ [4]
KM Hendricks and colleagues at Tufts University School of Medicine, Boston, investigated dietary components that may predispose HIV-positive patients to develop fat deposition. [5] They evaluated differences in past dietary intake between HIV-positive men who developed fat deposition and those who did not. They had 47 cases and 47 controls from the Nutrition for Healthy Living cohort and compared food records from six to 24 months before development of fat deposition. HIV-positive patients without fat deposition had greater overall energy intakes (kcal/kg; P = 0.03) and greater intakes of total protein (P = 0.01), total dietary fibre (P = 0.01), soluble dietary fibre (P = 0.01), insoluble dietary fibre (P = 0.03), and pectin (P = 0.02) than did HIV-positive patients with fat deposition. Those without fat deposition also tended to currently perform more resistance training (P = 0.05) and to not be current smokers (P = 0.05).
Comment
The benefits of dietary treatment of lipids in HIV-negative individuals may differ substantially from the results in HIV-positive people with dyslipidemia due to antiretroviral treatment as this has a completely different pathophysiology. Practising a well balanced diet will not be wrong, but high flying hopes should be substantiated by controlled studies first.
The findings of the Boston study show that in HIV-positive patients the risk factors for lipoaccumulation are the same as in the general population which raises to the question how would these patients look without HIV? They would most probably more obese than matched controls. However the borderline p-values should be looked at with caution.
A recent paper in Medical Hypotheses suggested that very low fat diets may be a useful approach to HIV-related lipodystrophy. [6]
Excessive flux of free fatty acids after eating a normal diet may overwhelm the ability of peripheral subcutaneous adipocytes to store triglycerides. This manifests as hypertryclyceridaemia and fat redistribution to truncal and visceral stores. They go on to suggest that chronic exposure of tissues to high levels of free fatty acids (FFA’s) may also induce insulin resistance. A very low fat diet (less that 15% of daily calories made up from fat intake) would reduce postprandial flux of FFA’s, reduce LDL cholesterol and may help to reduce visceral fat deposits. Such diets are also known to have a beneficial effect on insulin sensitivity.
References:
- Jenkins DJ, Kendall CW, Marchie A et al. The effect of combining plant sterols, soy protein, viscous fibers, and almonds in treating hypercholesterolemia. Metabolism. 2003 Nov;52(11):1478-83.
http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd= Retrieve&db=PubMed&list_uids=14624410&dopt=Abstract - Jenkins DJ, Kendall CW, Marchie A, et al. Effects of a dietary portfolio vs lovastatin on serum lipids and C-reactive protein. JAMA. 2003;290:502-510
http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd= Retrieve&db=PubMed&list_uids=12876093&dopt=Abstract - Anderson JW. Diet First, Then Medication for Hypercholesterolemia. JAMA. 2003;290:531-533.
http://jama.ama-assn.org:80/cgi/content/full/290/4/531#ACK - Featured Article. Should You Put Stock in This Portfolio? Wellness Letter, November 2003
http://www.wellnessletter.com/html/wl/2003/wlFeatured1103.html - Hendricks KM, Dong KR, Tang AM et al. High-fiber diet in HIV-positive men is associated with lower risk of developing fat deposition. Am J Clin Nutr. 2003 Oct;78(4):790-5.
http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd= Retrieve&db=PubMed&list_uids=14522738&dopt=Abstract - McCarty MF. Iatrogenic lipodystrophy in HIV patients – the need for very-low-fat diets. Med Hypotheses. 2003 Nov-Dec; 61(5-6): 561-6.
http://dx.doi.org/10.1016/S0306-9877(03)00230-5