NOW Foods Cod Liver Oil

Omega-3 (EPA and DHA)· evidence: Moderate

EPA and DHA are long-chain omega-3 fats found mainly in oily fish such as salmon, mackerel and sardines, and in algae. The NHS advises eating two portions of fish a week, one of them oily. People who eat no oily fish get very little EPA and DHA from their diet.

What counts on a label is the EPA plus DHA per daily dose, not the total amount of fish oil: a 1,000 mg fish oil capsule often contains only 300 mg of EPA and DHA. Authorised claims for heart, brain and vision need at least 250 mg a day, and many cheaper products fall short of that.

Large reviews have found that omega-3 supplements make little or no difference to heart attacks, strokes or deaths in the general population. They are a reasonable option for people who do not eat oily fish, and DHA intake matters in pregnancy and breastfeeding.

Typical dose: 250 to 500 mg of EPA plus DHA a day for general use; an extra 200 mg of DHA a day in pregnancy and breastfeeding. Check the EPA and DHA figures, not the fish oil total.

Safety: EFSA considers up to 5 g a day of EPA and DHA combined safe for adults. Avoid if you are allergic to fish (or shellfish, for krill oil). Talk to your GP or pharmacist if you take anticoagulants such as warfarin or antiplatelet medicines, or before surgery. Cod liver oil also contains vitamin A, so avoid it in pregnancy. Mild burps and fishy aftertaste are common.

Research we looked at:
Abdelhamid AS, Brown TJ, Brainard JS, et al. Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database Syst Rev 2020;3:CD003177.
EFSA NDA Panel. Scientific Opinion on the Tolerable Upper Intake Level of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA). EFSA Journal 2012;10(7):2815.
EFSA NDA Panel. Scientific Opinion on the substantiation of health claims related to EPA, DHA, DPA and maintenance of normal cardiac function. EFSA Journal 2010;8(10):1796.
NHS. Fish and shellfish. nhs.uk/live-well/eat-well/food-types/fish-and-shellfish-nutrition

Vitamin D3· evidence: Strong

Vitamin D3 (cholecalciferol) is the form the skin makes from sunlight. In the UK there is not enough strong sunlight from about October to March, so many people have low levels over winter. Good-quality trials show supplements reliably raise blood levels and correct deficiency, and that matters for bone health in people who are low.

The NHS advises everyone to consider 10 µg (400 IU) a day in autumn and winter, and all year round for people who get little sun, cover their skin, have darker skin or live in care homes. For people who already have adequate levels, large trials have not shown that extra vitamin D prevents falls, fractures or other illness.

In short: a modest daily dose is sensible and cheap insurance for most UK adults in winter. Very high doses are not better and should only be taken on medical advice.

Typical dose: 10 µg (400 IU) a day is the NHS advice for adults and children over 1. Doses of 25 µg (1,000 IU) to 50 µg (2,000 IU) are common and safe for adults. Babies under 1 need 8.5 to 10 µg a day unless they have more than 500 ml of formula.

Safety: Do not take more than 100 µg (4,000 IU) a day without medical advice (FSA/NHS); children aged 1 to 10 should not have more than 50 µg, and babies under 1 no more than 25 µg. Long-term very high intake can raise blood calcium, which can damage the kidneys and heart. People with kidney disease, sarcoidosis or high calcium levels should speak to their GP first.

Research we looked at:
NHS. Vitamin D. nhs.uk/conditions/vitamins-and-minerals/vitamin-d
Scientific Advisory Committee on Nutrition (SACN). Vitamin D and Health. 2016.
EFSA NDA Panel. Scientific opinion on the tolerable upper intake level for vitamin D. EFSA Journal 2023;21(8):8145.
Bolland MJ, Grey A, Avenell A. Effects of vitamin D supplementation on musculoskeletal health: a systematic review, meta-analysis, and trial sequential analysis. Lancet Diabetes Endocrinol 2018;6(11):847-858.

Vitamin A· evidence: Limited

Vitamin A (as retinol or retinyl esters, or as beta-carotene that the body converts) is needed for vision, skin and the immune system. Adults need 600 to 700 µg a day in the UK, and most people get enough from dairy, eggs, oily fish, liver and orange and green vegetables. Deficiency is rare in the UK.

There is little reason for well-fed adults to take extra vitamin A, and preformed vitamin A (retinol) builds up in the body. The NHS advises that people who eat liver weekly should not take supplements containing vitamin A, and that pregnant women should avoid them.

Beta-carotene from food is safe, but high-dose beta-carotene supplements increased lung cancer risk in smokers in large trials.

Typical dose: Adults need 600 µg (women) to 700 µg (men) a day from all sources (NRV on labels: 800 µg).

Safety: Avoid vitamin A (retinol) supplements in pregnancy or if trying to conceive; too much can harm an unborn baby. The NHS advises not having more than 1.5 mg (1,500 µg) a day from food and supplements combined, as long-term excess may weaken bones in later life. Smokers and former smokers should not take high-dose beta-carotene supplements.

Research we looked at:
NHS. Vitamin A. nhs.uk/conditions/vitamins-and-minerals/vitamin-a
EFSA NDA Panel. Scientific opinion on dietary reference values for vitamin A. EFSA Journal 2015;13(3):4028.
Omenn GS, Goodman GE, Thornquist MD, et al. Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease. N Engl J Med 1996;334(18):1150-1155.

Cost per daily dose lets you compare packs of different sizes fairly.Worked out from our current prices.