Research published in the American Journal of Clinical Nutrition has shown that man made trans fats, chemically altered vegetable fats, are more harmful than trans fats found naturally occuring in nature such as in nuts.
Women in the study did not see any effect in their total blood cholesterol levels, low-density lipoprotein or “bad” cholesterol, dangerous blood fats called triglycerides, and other blood indicators of heart risk when they ate diets high in these naturally occurring trans fats. The trans fats in their diet came from enriched butter.
Leading UK Nutritionist Yvonne Bishop-Weston said "Nutritionists have long pointed out that these man-made frankenstein mutant fats are the worst of all for your body. Although animal trans fats get off relatively lightly in this study that doesn't mean they are safe to eat just that the man made ones are even worse."
Some women did see a small decrease in their high-density lipoprotein or “good” cholesterol levels when they ate a diet rich in naturally occurring trans fats. This was more pronounced in women who were overweight, the study showed.