November/December 2003

Lipid Education Service
Newsbrief
J. David Schnatz, M.D.

During the past six months, there have been interesting articles on diet which appeared in the medical literature. The following articles have been selected for their interest, relevance to risk factors or current popularity.

"Effects of a Dietary Portfolio of Cholesterol-Lowering Foods vs Lovastatin on Serum Lipids and C-Reactive Protein" (1). Dr. Jenkins and his co-authors studied 46 patients, randomized in a comparison of a control lowfat diet (C) (n=16), the same diet and 20mg of Lovastatin (L) (n=14) and a modified diet (D) which was high in plant sterols, soy protein, viscous fibers and almonds (n=16). These 46 patients consisted of 25 men and 21 post-menopausal women, average age of 59 years and average BMI of 27.6. Diets prior to the study were routine, lowfat diets, and during the four week study, they were weight maintaining with the most striking part of the modified diet being a substitution of vegetable protein for most of the protein consumed. Lovastatin or a placebo were given and a capsule count done at the end of the study. During the four weeks of study, LDL decreased 8% in the C group whereas it decreased 32% for L and 29% for D (p<0.005 for both L and D compared with C). The LDL/HDL ratio did not change in C but was significantly lower for L and D (p<0.005), -30% (L) and -25% (D). For both LDL and LDL/HDL, the differences between L and D were not significant. In both groups, highly sensitive C-Reactive protein (HSCRP) was decreased (p<0.005).

This study indicates substantial benefits from a diet containing components that are part of recent dietary recommendations, and this benefit can be comparable to that from a modest dose of Lovastatin. Some of the problems are that the study was done on few patients and for only a few weeks. The significance of the HSCRP reduction with D remains to be seen.

"Adherence to a Mediterranean Diet and Survival in a Greek Population" (2). Twenty-two thousand forty-three participants, 20-86 years of age, without coronary artery disease, diabetes mellitus or cancer were recruited, prospectively, from all regions of Greece. The first author and colleagues had previously developed a nine point scale for quantification of adherence to a Mediterranean diet and revised it at a later time to include fish. For each beneficial component such as vegetables, legumes, fruits, nuts, cereals and fish, persons whose consumption was below the median were assigned a value of 0 and above the median, a value of 1. For each presumably detrimental component such as meat, poultry and dairy products, consumption below the median was given a value of 1 and above the median a 0. Daily physical activity was estimated as energy expended per kilogram body weight per day by assigning a metabolic equivalent to each activity and multiplying by time spent. A value of 1 was assigned to women drinking 5-25 grams of alcohol per day and to men drinking 10-50 grams per day. Follow-up was for 3-8 years, depending on the date of entry into the study.

Mortality was related to gender (males > females), age (logarithmic increase), and was decreased by physical activity. The most striking finding was a 2 point increment in the diet score being associated with a reduction in total mortality (p<0.001). Advantages of the study are that it is a prospective study of a large sample of the Greek population, using a previously validated dietary score. There may be confounding factors that have not been evaluated.

"A Low-Carbohydrate as Compared with a Low-Fat Diet in Severe Obesity" (3) and "A Randomized Trial of Low-Carbohydrate Diet for Obesity" (4). In the first trial, 132 subjects, 59 years of age, 82.5% male with an average BMI of 42.9 (weight=288 lbs.) were randomly assigned to a low carbohydrate (LC) diet (22% protein, 37% carbohydrate and 41% fat) which was compared with a lowfat (LF) diet (16% protein, 51% carbohydrate and 33% fat). During the course of the study, 53 subjects (40%) dropped out, 21 from the LC diet and 32 from the LF diet. After six months, weight loss was analyzed, using the last observation for those who dropped out. Those on the LF diet lost 12.8 lbs. (4.4%) and those on the LC diet 4.2 lbs. (1.4%) (p=0.002). In this study, lipids were not adversely affected and LC patients had greater decreases in triglyceride (p=0.001).

In the second trial, 63 subjects, 44 years of age, 30% male with an average BMI of 34 (weight 216 lbs.) were randomly assigned to LC (carbohydrate limited to 20g/d and then gradually increased as per the Atkin's Diet) or LF (15% protein, 60% carbohydrate and 25% fat). Forty-nine subjects completed three months, 42 six months and 37 completed 12 months, i.e., by the end of the study, 26 (41%) had dropped out. Analyses were carried out, handling the drop-outs in the same manner as the other study. Those on the LC diet lost more weight than LF at three months (p=0.001) and at six months (p=0.002), but by 12 months there was no difference between LC and LF (p=0.27) although each group had lost significant weight from baseline, 7.3 and 4.5% (p<0.05 in each case). There was no significant difference between LC and LF in CHOL or LDL over the 12 months. However, triglyceride dropped more at 12 months on LC and HDL rose more (p=0.04 for each). The authors conclude that "Longer and larger studies are required to determine the long-term safety and efficacy of low-carbohydrate, high-protein, high-fat diets."

In the editorial accompanying the above two articles (5), Drs. Bonow and Eckel made the points that although there was greater weight loss with LC than LF, the magnitude of the loss was relatively small, adherence to diet was low, there was no difference in LC and LF at 12 months, the rise in HDL that comes with sufficient fat in the diet has not been shown to be beneficial, LC diets contain an increased amount of saturated fat that can be detrimental, they lack important vitamins and fibers, there is a paucity of data on LC diets, and LF coupled with physical activity have been shown to produce weight loss. They conclude that "the recipe for effective weight loss is a combination of motivation, physical activity and caloric restriction" and that "physicians should continue to recommend a healthy lifestyle that includes regular physical activity and a balanced diet."

In a review of LC diets gleaned from a search of the literature from 1966-2003, the conclusion was "there is insufficient evidence to make recommendations for or against the use of low-carbohydrate diets, particularly among participants older than age 50 years, for use longer than 90 days, or for diets of 20g/d or less of carbohydrates" (6).

In a recently published study in children on a ketogenic diet (LC) for control of seizures (7), there were significant elevations of CHOL, LDL, VLDL, non-HDL and TG (p<0.001 for each) along with significant decreases in HDL (p<0.001).

Some patients appear to achieve better weight loss on LC than LF, but the question is "how long can we keep patients on a high-fat diet without increasing the risk of vascular disease?" (8). The principles imbedded in these articles and concepts leading to LC and LF diets are that there are good and bad fats as well as good and bad carbohydrates. The ideal for weight loss incorporates a predominance of good fats and good carbohydrates in a calorically restricted diet, supplemented by physical activity commensurate with the patients physical status.