PUFAs, MUFAs, And HDL

[Guest guest]

2 Recent studies looking at the PUFA, MUFA issue and

HDL. The first one, we did, and looked at the effect

of a lower fat diet on the " Activity " of HDL and not

just the " level " of HDL.

The second is from a researher (vogel) who does lots

of studies in animals and really questions the

promotion of MUFAs to the general public as being

" healthy " .

Regards

Jeff

Rigorous Adherence to a Low-Fat, High-Fiber Diet along

with Daily Exercise May Enhance Anti-inflammatory

Properties of HDL

" Effect of a Diet and Exercise Intervention in

Inflammatory/Anti-inflammatory Properties of HDL in

Men with Cardiovascular Risk Factors, " CK, Ng

C, et al, J Appl Physiol, 2006 Aug 10;

Summary: In a study involving 22 overweight and obese

men (mean BMI: 33) with risk factors for

cardiovascular disease, strict adherence to a

high-fiber, low-fat diet, along with daily aerobic

exercise, for a period of 3 weeks, was found to

increase the anti-inflammatory properties of HDL

cholesterol, improving its function, despite the

overall reduction in HDL cholesterol levels. In

addition, reductions were found in total cholesterol,

LDL cholesterol, triglycerides, total cholesterol:HDL

cholesterol ratio, and lipid hydroperoxides. Of the 22

subjects, 15 were diagnosed with the metabolic

syndrome, according to the WHO criteria, 3 subjects

were diagnosed with coronary artery disease, and the

remaining 4 subjects had at least 1 or 2 metabolic

syndrome factors. For a period of 3 weeks, subjects

participated in a residential program (Pritikin

Longevity Center) in which they adhered to a diet

consisting of 12-15% of calories from fat, 15-20% of

calories from protein, primarily in the form of plant

proteins and limited amounts of animal protein

(non-fat dairy, fish, fowl), and 65-70% of calories

from mostly unrefined carbohydrates high in fiber, in

the form of whole grain (5 or more servings/d),

vegetables (4 or more servings/d), and fruit (3 or

more servings/d). The diet contained more than 40 g of

fiber daily, and no added fats or sugars were added to

the meals. Aside from animal protein, subjects were

provided food ad libitum. The exercise program

consisted of 45-60 minutes/day of walking on a

treadmill at the training heart rate determined

individually for each subject at the start of the

program through a graded treadmill stress test.

Fasting blood samples were taken at baseline, and then

again after the 3 week intervention. Researchers

specifically set out to determine the effects of such

an intervention on the inflammatory and

anti-inflammatory properties of HDL. Low-fat diets

have been criticized for their effect of lowering HDL

levels, which is considered to increase the risk of

cardiovascular disease. Researchers in this study set

out to determine how such an intervention would affect

not only the quantity of HDL particles, but the

quality of HDL. That is to say, blood samples taken

from subjects were measured for the ability of subject

HDL to alter LDL-induced monocyte chemotactic activity

(MCA) in a human artery wall coculture. Induction of

MCA by control LDL in the absence of HDL was

normalized to 1.0. After HDL addition, the presence of

pro-inflammatory HDL was determined to be values >1.0,

and the presence of anti-inflammatory HDL was

determined to be values <1.0. Results showed that

after the 3-week intervention, while overall HDL

levels decreased, the HDL inflammatory index decreased

from pro-inflammatory (1.14) to anti-inflammatory

(0.94). Furthermore, reductions in total cholesterol,

LDL cholesterol, total cholesterol: HDL cholesterol

ratio, triglycerides, and lipid hydroperoxides, while

an increase in platelet-activating factor

acetylhydrolase was found. No changes were found in

apolipoprotein A-I level and paraoxonase 1 and 3

activity, which play a role in regulating HDL

function. The results of this study suggest that

adherence to a regimen of daily aerobic exercise and

following a high-fiber, low-fat diet may qualitatively

improve the function of HDL while quantitatively

decreasing it.

Curr Opin Lipidol. 2003 Feb;14(1):41-6.

Dietary monounsaturated versus polyunsaturated fatty

acids: which is really better for protection from

coronary heart disease?

Lada AT,

Rudel LL.

Department of Pathology, Wake Forest University School

of Medicine, Winston-Salem, North Carolina 27157, USA.

PURPOSE OF REVIEW: The purpose is to evaluate recent

findings concerning dietary fats and the risk of

coronary heart disease. Monounsaturated fatty acids

are often regarded as healthy, and many have

recommended their consumption instead of saturated

fatty acids and polyunsaturated fatty acids. Support

for the benefits of monounsaturated fatty acids comes

largely from epidemiological data, but they have not

been an isolated, single variable in such studies.

Beneficial effects on the plasma lipid profile and LDL

oxidation rates have also been identified. More recent

findings have questioned the impact of suspected

beneficial effects on coronary heart disease,

indicating that studies with more conclusive endpoints

are needed. RECENT FINDINGS: Human dietary studies

often produce conflicting results regarding the

effects of monounsaturated and polyunsaturated fatty

acids on the plasma lipid profile. Monounsaturated and

polyunsaturated fatty acids both appear to reduce

total and LDL-cholesterol compared with saturated

fatty acids; however, the effect on HDL is less clear.

Lowered HDL levels in response to low-fat or

polyunsaturated fatty acid diets and the decreased

protection from oxidation of polyunsaturated fatty

acid-enriched LDL may not indicate increased coronary

heart disease risk. Several lines of evidence also

suggest that polyunsaturated fatty acids may protect

against atherosclerosis. SUMMARY: Recommendations to

substitute monounsaturated fatty acids for

polyunsaturated fatty acids or a low-fat carbohydrate

diet seem premature without more research into the

effects on the development of atherosclerosis. Current

opinions favoring monounsaturated fatty acids are

based on epidemiological data and risk factor

analysis, but are questioned by the demonstrated

detrimental effects on atherosclerosis in animal

models.

PMID: 12544660