Good cholesterol may actually increase the risk of heart disease in older women, according to new research. Hormonal changes during the menopause can cause the 'healthy' HDL blood fat to become harmful - by enlarging the particles, say scientists. This increases the risk of blood clots due to hardening of the arteries - which can trigger heart attacks or strokes. The finding adds to growing evidence that women's heart disease rates rise dramatically after the menopause because even good cholesterol becomes bad.