Diets high in saturated fat lead to lower levels of Lp(a)

This study was published in the Journal of Lipid Research 1992 Oct;33(10):1493-501

Study title and authors:
Effect of dietary cis and trans fatty acids on serum lipoprotein[a] levels in humans.

Mensink RP, Zock PL, Katan MB, Hornstra G.
Department of Human Biology, Limburg University, Maastricht, The Netherlands.

This study can be accessed at: http://www.ncbi.nlm.nih.gov/pubmed/1431574

The lead author of the study, Professor Ronald Mensink, notes that a high level of lipoprotein[a] (Lp[a]) is a strong risk factor for coronary heart disease.

This study set out to determine the influence of saturated fat, monounsaturated fat, polyunsaturated fat and trans-fat on levels of Lp(a). The study involved three strictly controlled experiments with healthy men and women with normal cholesterol levels.

Experiment 1
58 subjects consumed a control diet high in saturated fat for 17 days. For the next 36 days, 6.5% of total energy intake from saturated fat was replaced by:
(i) Monounsaturated fat plus polyunsaturated fat (monounsaturated fat diet; 29 subjects).
(ii) Polyunsaturated fat alone (polyunsaturated fat diet; 29 subjects).

Experiment 1 results:
(a) In the group that switched from the high saturated fat diet to the monounsaturated fat diet, Lp(a) levels increased by 8.3%.
(b) In the group that switched from the high saturated fat diet to the polyunsaturated fat diet, Lp(a) levels increased by 8.1%.

Experiment 1 shows that higher monounsaturated fat and polyunsaturated fat diets lead to higher Lp(a) levels compared to higher saturated fat diets.

Experiment 2
59 subjects consumed three different diets for three weeks each in random order. The diets differed by their content of saturated fat, monounsaturated fat (oleic acid) or trans-fat (derived from oleic acid).

The diets were composed of:
(i) 19.4% saturated fat, 12.8% monounsaturated fat, 1.8% trans-fat. (High saturated fat diet).
(ii) 9.5% saturated fat, 23.0% monounsaturated fat, no trans-fat. (High monounsaturated fat diet).
(iii) 10.0% saturated fat, 12.6% monounsaturated fat, 10.9% trans-fat. (High trans-fat diet).

Experiment 2 results:
(a) The Lp(a) levels of those on the high monounsaturated fat diet were 23.0% higher than those on the high saturated fat diet.
(b) The Lp(a) levels of those on the high trans-fat diet were 73.1% higher than those on the high saturated fat diet.

Experiment 2 shows that higher monounsaturated fat and trans-fat diets lead to higher Lp(a) levels compared to higher saturated fat diets.

Experiment 3
56 subjects consumed three different diets for three weeks each in random order. The diets differed by their content of saturated fat, polyunsaturated fat (linoleic acid) or trans-fat (elaidic acid).

The diets composed of:
(i) 20.1% saturated fat, 4.3% polyunsaturated fat, 0.3% trans-fat. (High saturated fat diet).
(ii) 11.0% saturated fat, 12.5% polyunsaturated fat, 0.1% trans-fat. (High polyunsaturated fat diet).
(iii) 10.3% saturated fat, 3.8% polyunsaturated fat, 7.7% trans-fat. (High trans-fat diet).

Experiment 3 results:
(a) The Lp(a) levels of those on the high polyunsaturated fat diet were the same as those on the high saturated fat diet.
(b) The Lp(a) levels of those on the high trans-fat diet were 23.2% higher than those on the high saturated fat diet.

Experiment 3 shows that higher trans-fat diets lead to higher Lp(a) levels compared to higher polyunsaturated fat and saturated fat diets.

Taken as a whole these three experiments show that a diet high in saturated fat leads to lower levels of Lp(a) compared to diets high in polyunsaturated fat, monounsaturated fat and trans-fat.

Please watch the following informative youtube clip, "Enjoy Eating Saturated Fats: They're Good for You. Donald W. Miller, Jr., M.D.", by Dr Donald W Miller. Dr Miller is a heart surgeon and practices and teaches heart surgery at the University of Washington and at the Swedish Medical Center. Dr Miller has published three books; "The Practice of Coronary Artery Bypass Surgery", "Atlas of Cardiac Surgery" and "Heart in Hand".

The youtube clip, which lasts for 53 minutes, can be accessed at http://www.youtube.com/watch?v=vRe9z32NZHY