Long-term beta-carotene supplementation found to improve brain function

On Monday I reported on a couple of recently published studies which support the notion that fish fats are good for the brain. In particular, these studies assessed the potential impact fish-eating and higher levels of so-called omega-3 fats have on the ageing brain. And hot on the heals of this research has come a study, published this week in the Archives of Internal Medicine, which suggests that another nutrient that has some ability to preserve our mental faculties as we age comes in the form of beta-carotene [1].

This study concerned commenced in 1982, and originally treated men aged 40-84 with aspirin, beta-carotene or placebo. The study design itself was complex, and the details (if you need them) were that individuals were treated with one of the following combinations:

real aspirin and real beta-carotene

placebo (in place of the beta-carotene) and real aspirin

placebo (in place of the aspirin) and real beta-carotene

two placebos

The dose of beta-carotene given in the study was 50 mg, taken on alternate days.

The study went on to recruit some newer participants in 1998.

The researchers involved in this study assessed the brain function of both older and newer recruits using tests which measured ‘general cognition’ and something known as ‘verbal memory’ (essentially a test of short term memory).

In this study, the older recruits had taken beta-carotene for an average of 18 years, while the newer recruits had taken it for an average of just a year. In the newer recruits, there was beta-carotene appeared to have made no difference in terms of brain function. However, in the older recruits, those who had been taking the beta-carotene were found to have significantly improved general brain function and verbal memory.

So, the evidence suggests that long term supplementation with beta-carotene benefits the brain, but short-term supplementation doesn’t. Which, to my mind demonstrates one of the limitations of this sort of study and supplementation in general: it can take a long time before any benefits are seen, as I pointed out in a recent blog.


Nevertheless, the results of this study are encouraging, and they should at least cause us to consider how beta-carotene may be exerting whatever beneficial effect it has on the brain.

Some have theorised that brain ageing is accelerated through a process known as ‘oxidative damage’, reeked by molecular entities known a ‘free radicals’ [2]. One of beta-carotene’s effects is to reduce free radical action and oxidative damage.

Those keen to ensure a good intake of beta-carotene, as well as other related nutrients from what is known as the ‘carotenoid’ family, may look to deeply coloured fruit and vegetables including carrots, spinach, apricots, cantaloupe melon and mango. Supplementation is, of course, another option. It’s perhaps worth bearing in mind that beta-carotene supplementation has been associated with an increased risk of lung cancer in smokers. Some have questioned these findings on the basis that the form of beta-carotene used in these studies was ‘synthetic’ in form.

At this stage, though, it seems prudent for smokers not to be taking beta-carotene in supplement form. And those considering supplementation might want to veer towards ‘natural’ forms of beta-carotene. (Synthetic beta-carotene is made up of one specific molecule known as ‘all-trans beta-carotene’. Natural beta-carotene contains two molecules: all-trans beta-carotene and what is known as ‘9-cis beta-carotene).


1. Grodstein F, et al. A Randomized Trial of Beta Carotene Supplementation and Cognitive Function in Men: The Physicians’ Health Study II. Arch Intern Med. 2007;167(20):2184-2190.

2. Deschamps V, et al. Nutritional factors in cerebral aging and dementia: epidemiological arguments for a role of oxidative stress. Neuroepidemiology 2001;20(1):7-15.

5 Responses to Long-term beta-carotene supplementation found to improve brain function

  1. James H 16 November 2007 at 9:27 pm #

    If you want to boost your beta-carotene levels, consider adding avocados to your salads. They have been show to increase absorption of the beta-carotene by 15.3 times. This is likely to be because beta-carotene is lipid (fat) soluble (PMID: 15735074). The same affect is likely to had from an oil dressing, but not a “low fat” one!

  2. helen 18 November 2007 at 9:28 pm #

    cod liver oil is the best natural source of vitamin A

    & yes avocados are one of the best fat containing foods. People we really have to get over this obsession with low fat everything & realise that taking a natural substance out of our diets & replacing it with unnatural trans fats or too much vegetable fat is detremental to our lives. Certainly eating high sugar low fat products is the most stupid thing we can do & not only will it make you fat it will make you sick unto death!

  3. helen 18 November 2007 at 9:31 pm #

    & yes avocados are vegetable fat but it is a highly nutritious, unprocessed natural food.

  4. James H 24 November 2007 at 10:23 am #

    Cod liver oil is not a source of beta-carotene. As you say Cod Liver oil has vitamin A in, however Beta-carotene is a precursor of vitamin A.

    The best sources of natural Beta-carotene is in fruit and vegetables such as sweet potatoes, carrots, kale, spinach, turnip greens, winter squash, collard greens, and fresh thyme. All pretty low GI too! 🙂


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