I read on https://thelivingproofinstitute.com/time-day-supplements (mirror):

It is best to take antioxidants such as turmeric, resveratrol, glutathione, etc… at bedtime. The reason in the literature is still not very clear but they seem to be more effective when taken at night. If twice a day dosing is called for – take then in the morning and at bedtime.

Has it been shown in scientific studies that antioxidants such as turmeric, resveratrol, glutathione, etc… should be taken at bedtime, and if so, what explains it?

  • As far as I know there is no definite proof that the mentioned substances act as antioxidants in the human body. They can very well act as oxidants in the laboratory, but not within the human body. – Jan Oct 10 at 14:39
  • @Jan Oh, they do act as antioxidants, or even prooxidants, in the human body. But it is questionable whether that is a good thing or how much one would benefit from it. In my view that category represents mainly an outdated attempt of making sense of things. – LangLangC Oct 10 at 15:03
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    OK, yes, If I need to rephrase: no benefical antioxidant effects of those substances in the human body have been proven so far. – Jan Oct 10 at 15:07
  • This comment does not address your question directly, but it may give some insight into how resveratrol is processed by the body. This is a business website, so there is always the possibility of bias, but they are professionals and they do cite studies. brightoncompounding.com/pharmacists-take-resveratrol – Gordon Oct 11 at 13:55
  • Sorry, I forgot to mention that the above comment is about resveratrol. My comment is not meant to replace LangLangC's answer, my intent is merely to provide more information that may be useful in your research. – Gordon Oct 11 at 13:58
up vote 3 down vote accepted

This question has an implicit claim in it: that taking antioxidants is effective in the first place. As that is very much in doubt now from the start, it explains very well why there is no consensus over when to take them. Especially if all these substances are all lumped into that one basket called "antioxidants".

Our Cochrane review from 2008 demonstrated that antioxidant supplements seem to increase mortality. This review is now updated.

We found no evidence to support antioxidant supplements for primary or secondary prevention. Beta-carotene and vitamin E seem to increase mortality, and so may higher doses of vitamin A. Antioxidant supplements need to be considered as medicinal products and should undergo sufficient evaluation before marketing.

Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C: "Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases", 4 March 2012.

That makes the question unanswerable for all substances simply labeled "antioxidants", or leads to the conclusion that for this effect they are named for it doesn't matter. But it is questionable whether that being an antioxidant is a good thing or how much one would benefit from it. In my view that category represents mainly an outdated attempt of making sense of things.

We therefore would have to look at each of these substances and evaluate their effectiveness or mechanisms of action etc.

As an example, let's look at turmeric, a very promising agent for a variety of ailments, that I love, personally:

Background

Turmeric, a plant related to ginger, is grown throughout India, other parts of Asia, and Central America. Javanese turmeric (Curcuma xanthorrhiz) is a different plant and not discussed in this fact sheet.

Historically, turmeric has been used in Ayurvedic medicine, primarily in South Asia, for many conditions, including breathing problems, rheumatism, serious pain, and fatigue.

Today, turmeric is used as a dietary supplement for inflammation; arthritis; stomach, skin, liver, and gallbladder problems; cancer; and other conditions. Turmeric is a common spice and a major ingredient in curry powder. Its primary active ingredients, curcuminoids, are yellow and used to color foods and cosmetics.

Turmeric’s underground stems (rhizomes) are dried and made into capsules, tablets, teas, or extracts. Turmeric powder is also made into a paste for skin conditions.

How Much Do We Know?

We have a lot of research, including studies done in people, on turmeric for a variety of health conditions.

What Have We Learned?

Claims that curcuminoids found in turmeric help to reduce inflammation aren’t supported by strong studies.

Preliminary studies found that curcuminoids may

  • Reduce the number of heart attacks bypass patients had after surgery
  • Control knee pain from osteoarthritis as well as ibuprofen did
  • Reduce the skin irritation that often occurs after radiation treatments for breast cancer.
  • Other preliminary studies in people have looked at curcumin, a type of curcuminoid, for different cancers, colitis, diabetes, surgical pain, and as an ingredient in mouthwash for reducing plaque.
  • The National Center for Complementary and Integrative Health (NCCIH) has studied curcumin for Alzheimer’s disease, rheumatoid arthritis, and prostate and colon cancer.

What Do We Know About Safety?
Turmeric in amounts tested for health purposes is generally considered safe when taken by mouth or applied to the skin. High doses or long-term use of turmeric may cause gastrointestinal problems.

National Center for Complementary and Integrative Medicine, 2016

Or to put more bluntly,

  • There is little reliable evidence to support the use of turmeric for any health condition because few clinical trials have been conducted.

Preliminary findings from animal and other laboratory studies suggest that a chemical found in turmeric — called curcumin — may have anti-inflammatory, anticancer, and antioxidant properties, but these findings have not been confirmed in people. (As quoted from Turmeric: Tasty in Curry, Questionable as Medicine, 2014)

The above is not meant to wholly dismiss curcuma, or the question, but a reminder to see it as Turmeric: lots of potential, but beware of the hype.

As the question is quite broad and about a lot of those substances or preparations, let me close with: digestion, metabolism etc. at night time are different. That probably effects bioavailability and pharmacodynamics a lot. I suspect that it is the effect or the same effect size for all the substances mentioned.

Although that is speculation, it is also the current line of inquiry for researchers:

Further randomized, double blinded clinical trials with a greater sample size, homogenous test and tasks of cognitive or memory function, as well as longer duration of treatment and follow-up are compulsory to achieve more conclusive results. In addition, it is suggested to conduct future clinical trials by evaluation of resveratrol products with improved bioavailability by the use of novel methods such as nanoformulations or in combination with metabolism inhibitors.

Mohammad Hosein Farzaei & Roja Rahimi & Shekoufeh Nikfar & Mohammad Abdollahi: "Effect of resveratrol on cognitive and memory performance and mood: A meta-analysis of 225 patients", Pharmacological Research Volume 128, February 2018, Pages 338-344. DOI

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