Osavi ADEK Vitamins

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.

Vitamin E· evidence: Limited

Vitamin E is a group of fat-soluble compounds (tocopherols and tocotrienols); alpha-tocopherol is the form the body keeps and the one labels count. It is found in plant oils, nuts and seeds, and the NHS says you should be able to get all you need from your diet. Deficiency is very rare and usually linked to conditions that stop fat being absorbed.

Large, long trials of high-dose vitamin E have not shown benefits for heart disease, cancer or general health in well-nourished people. Some found possible harm: the SELECT trial found more prostate cancer in men taking 400 IU a day, and a meta-analysis linked very high doses to slightly higher overall mortality.

Natural vitamin E (d-alpha-tocopherol) is more potent per IU-labelled milligram than synthetic (dl-alpha). Mixed tocopherols and tocotrienols are marketed as closer to food, but there is little good human evidence that they make a difference.

Typical dose: UK guidance: about 4 mg a day for men and 3 mg for women (NRV on labels: 12 mg). Supplements often give 100 to 400 IU (roughly 67 to 268 mg natural vitamin E).

Safety: The FSA advises that 540 mg (800 IU) a day or less from supplements is unlikely to cause harm; EFSA's upper level for adults is 300 mg a day. High doses can increase bleeding risk, so speak to your GP if you take warfarin, other anticoagulants or antiplatelet drugs, or before surgery. Long-term high-dose use is not advised for smokers or men concerned about prostate health.

Research we looked at:
NHS. Vitamin E. nhs.uk/conditions/vitamins-and-minerals/vitamin-e
EFSA NDA Panel. Scientific opinion on dietary reference values for vitamin E as alpha-tocopherol. EFSA Journal 2015;13(7):4149.
Klein EA, Thompson IM, Tangen CM, et al. Vitamin E and the risk of prostate cancer: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA 2011;306(14):1549-1556.
Miller ER, Pastor-Barriuso R, Dalal D, et al. Meta-analysis: high-dosage vitamin E supplementation may increase all-cause mortality. Ann Intern Med 2005;142(1):37-46.

Vitamin K2 (MK-7)· evidence: Limited

Vitamin K2 (menaquinone, usually as MK-7 in supplements) is one of the forms of vitamin K. The body needs vitamin K to make proteins involved in blood clotting and bone. Most adults get enough vitamin K from green vegetables, vegetable oils and some fermented foods, and true deficiency is rare in healthy adults.

Vitamin K2 is often sold alongside vitamin D3 on the idea that it helps direct calcium into bone. Trials of K2 on bone density and fractures are small and mixed, and the effect in well-nourished people is uncertain. Claims about arteries or heart health are not established.

Adding K2 to a vitamin D supplement is reasonable but not necessary for most people. It mainly adds cost.

Typical dose: Adults need about 1 µg per kg of body weight a day (around 70 µg for a 70 kg adult), mostly met by diet. Supplements usually give 45 to 200 µg of MK-7.

Safety: Vitamin K can stop warfarin and similar anticoagulants (vitamin K antagonists) working properly. Anyone on warfarin must not take vitamin K supplements without talking to their GP or anticoagulant clinic. The FSA notes that 1 mg or less a day from supplements is unlikely to cause harm in other people.

Research we looked at:
NHS. Vitamin K. nhs.uk/conditions/vitamins-and-minerals/vitamin-k
EFSA NDA Panel. Dietary reference values for vitamin K. EFSA Journal 2017;15(5):4780.
Mott A, Bradley T, Wright K, et al. Effect of vitamin K on bone mineral density and fractures in adults: an updated systematic review and meta-analysis of randomised controlled trials. Osteoporos Int 2019;30(8):1543-1559.

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