Interactions with Dietary Supplements

Coenzyme Q10
It has been clearly documented that HMG Co-A reductase inhibitors, including lovastatin,¹ deplete coenzyme Q10 (CoQ10) levels in the blood, an effect that may be responsible for other side effects of the drug, such as abnormal liver function. In a double-blind trial, blood levels of CoQ10 were measured in 45 people with high cholesterol treated with lovastatin (20–80 mg per day) or pravastatin (10–40 mg per day) for 18 weeks.² A significant decline in blood levels of CoQ10 occurred with both drugs. Supplementation with 90–100 mg per day CoQ10 has been shown to prevent reductions in blood levels of CoQ10 due to simvastatin.^{3 4} However, some investigators have questioned whether it is worthwhile or necessary for individuals taking HMG-CoA reductase inhibitors to supplement with CoQ10.⁵ Until more is known, people taking lovastatin should ask a doctor about supplementation with 30–100 mg CoQ10 per day.

Fibre (soluble)
Soluble fibre is found primarily in fruit, beans, and oats, but it is also available separately as pectin, oat bran, and glucomannan. Two sources of soluble fibre—pectin (found in fruit) and oat bran (a component of porridge also available by itself)—have been reported to interact with lovastatin.⁶ The fibre from these two sources appears to bind the drug in the gastrointestinal tract and reduce absorption of the drug as a consequence. People taking this drug should avoid concentrated intake of soluble fibre, as taking lovastatin with a high soluble-fibre diet leads to reduced drug effectiveness.

Niacin (Vitamin B3, nicotinic acid)
Niacin is a vitamin used to lower cholesterol. Large amounts of niacin taken with lovastatin have been reported to cause potentially serious muscle disorders (myopathy or rhabdomyolysis).⁷ However, niacin also enhances the cholesterol-lowering effect of lovastatin.⁸ Taking as little as 500 mg three times per day of niacin with lovastatin has been shown to have these complementary, supportive actions with almost none of the side effects seen when higher amounts of niacin are taken.⁹ Nevertheless, individuals taking lovastatin should consult with their doctor before taking niacin.

Sitostanol
A synthetic molecule related to beta-sitosterol, sitostanol, is available in a special margarine and has been shown to lower cholesterol levels. In one study, supplementing with 1.8 grams of sitostanol per day for six weeks enhanced the cholesterol-lowering effect of various statin drugs.¹⁰

Vitamin A
A study of 37 people with high cholesterol treated with diet and HMG-CoA reductase inhibitors found serum vitamin A levels increased over two years of therapy.¹¹ It remains unclear whether this moderate increase should suggest that people taking lovastatin have a particular need to restrict vitamin A supplementation.

Vitamin E
Oxidative damage to LDL (“bad”) cholesterol is widely believed to contribute to heart disease. In a double-blind trial, lovastatin was found to increase oxidative damage to LDL cholesterol and vitamin E was reported to protect against such damage, though not to completely overcome the negative effect of lovastatin.¹² This study suggests that people taking lovastatin might benefit from supplemental vitamin E.