Many double-blind trials have demonstrated that fish oils (also called fish-oil concentrates) containing EPA and DHA (mentioned above) lower TG levels.¹ The amount of fish oil used in much of the research was an amount that provided 3,000 mg per day of omega-3 fatty acids. To calculate how much omega-3 fatty acid is contained in a fish oil supplement, add together the amounts of EPA and DHA. For example, a typical 1,000-mg capsule of fish oil provides 180 mg of EPA and 120 mg of DHA (total omega-3 fatty acids equals 300 mg). Ten of these capsules would contain 3,000 mg of omega-3 fatty acids. Other sources of omega-3 fatty acids, such as flaxseed oil, do not lower TGs. While flaxseed oil has other benefits, it should not be used for the purpose of reducing TGs.

Cod liver oil, another source of omega-3 fatty acids, has also been found to lower TGs.² Cod liver oil is less expensive than the fish oil concentrates discussed previously. However, cod liver oil also contains relatively large amounts of vitamin A and vitamin D; too much of either can cause side effects. In contrast, fish oil concentrates have little or none of these vitamins. Individuals wishing to use cod liver oil as a substitute for a fish-oil concentrate should consult a doctor.

Omega-3 fatty acids from fish oil and cod liver oil have been reported to affect blood in many other ways that might lower the risk of heart disease.³ However, these supplements sometimes increase LDL cholesterol—the bad form of cholesterol. A doctor can check to see if fish oil has this effect on an individual. Research shows that when 900 mg of garlic extract is added to fish oil, the combination still dramatically lowers TG levels but no longer increases LDL cholesterol.⁴ Therefore, it appears that taking garlic supplements may be a way to avoid the increase in LDL cholesterol sometimes associated with taking fish oil. People who take fish oil may also need to take vitamin E to prevent the oil from undergoing potentially damaging oxidation in the body.⁵ It is not known how much vitamin E is needed to prevent such oxidation. The amount required would presumably depend on the amount of fish oil used. In one clinical trial, 300 IU of vitamin E per day prevented oxidation damage in individuals taking 6 grams of fish oil per day.⁶

Guggul, a mixture of ketonic steroids from the gum oleoresin of Commiphora mukul, is an approved treatment of hyperlipidemia in India and has been a mainstay of Ayurvedic herbal approaches to preventing atherosclerosis. Clinical trials indicate that guggul is effective in the treatment of high TGs; in one trial, serum TGs fell by 30.3%.⁷

However, these results have not been confirmed by large, controlled trials. The recommended daily intake of guggul is typically based on the amount of guggulsterones in the extract. The recommended amount of guggulsterones is 25 mg three times per day. Most extracts contain 5–10% guggulsterones. Guggul’s effect on TGs should be monitored for three to four months, and guggul may be taken long term if successful in lowering TGs.

Pantethine is a byproduct of pantothenic acid (vitamin B5). Several clinical trials have shown that 300 mg of pantethine taken three times per day will lower TG levels.^8,9,10 Pantothenic acid, which is found in most B vitamins, does not have this effect.

The niacin form of vitamin B3 is used by doctors to lower cholesterol levels, but niacin also lowers TG levels.¹¹ The amount of niacin needed to achieve worthwhile reductions in cholesterol and TG levels is several grams per day. Such quantities can cause side effects, including potential damage to the liver, and should not be taken without the supervision of a doctor. Some doctors recommend inositol hexaniacinate (a special form of vitamin B3) as an alternative to niacin. A typical amount recommended is 500 mg three times per day.^12,13 This form of vitamin B3 does not typically cause a skin flush and is said to be safer for the liver than niacin. However, the alleged safety advantage of inositol hexaniacinate needs to be confirmed by additional clinical trials. Moreover, it is not clear whether inositol hexaniacinate is as effective as niacin at lowering cholesterol and TG levels.