Is it Brain Fog – or Something More Serious? Part 1

Is there an Alzheimer’s prevention diet? Part one of a report on how to reduce your risk.


I know that at menopause many women experience brain fog, or memory issues, but more worrying is the prospect that it may be something worse.

Does what you eat affect your risk for dementia later in life and, if so, what is the best diet to protect your brain and prevent cognitive decline?

With subjects like this I turn to an expert and Patrick Holford is a leading nutritionist who has been studying the effect of nutrition on brain function and mood for many years.

He has written an extensive report on how you help yourself to reduce the risk for Alzheimer’s and I am sharing it here in two parts: first what  you can do positively and in part 2 what you need in order to avoid or reduce that risk.

The Alzheimer’s Prevention Diet

Many studies have been published with different results ranging from no effect at all, as reported in a study in Sweden[i], to over a 90% reduced risk of Alzheimer’s, as reported in a study in Finland and Sweden which compared those with the a ‘healthy’ versus unhealthy diet in mid-life for future risk of developing Alzheimer’s disease and dementia 14 years later.

Those who ate the healthiest diet had an 86-90% decreased risk of developing dementia and a 90-92% decreased risk of developing Alzheimer’s disease.[ii]

Many of these studies are similar in design, by looking at mid-life diet then tracking a group of people over time to see who does or doesn’t develop dementia or its most common type, Alzheimer’s disease.

Many also look at some measure of coherence to a ‘Mediterranean’ diet, which usually means eating more fruit, vegetables, legumes, nuts and seeds, as well as more fish, less meat and sometimes some or more wine.

Others compare to the standard recommendations for a ‘healthy’ diet made by the country’s authorities. Some foods or drinks could go either way. For example, some studies suggest coffee drinking might reduce risk, yet coffee increase homocysteine and this is an amino acid found in the blood.

Elevated levels of homocysteine have been associated with narrowing and hardening of the arteries, which is a strong predictor of risk. Alcohol consumption, especially red wine, may reduce risk in moderation but possibly increase risk in excess.

Another way to answer the question regarding the best anti-dementia diet is to look at studies that have linked specific foods or drinks to risk of cognitive decline then build up the brain-friendly diet from there.

These studies can also help define how much of the food or drink is optimal, or too much for those foods or drinks that increase risk.

Protective foods

One of the first good studies was carried out in Norway more than a decade ago by Eha Nurk and Helga Refsum and colleagues in Norway.[iii] [iv] They found that:

Tea – the more you drink the better. The tea benefit has been confirmed more recently in a study in Singapore, with green tea being marginally better than black tea.[v]

However, this benefit was not found in a UK Biobank study, which reported tea and coffee drinking to be associated with worsening cognition compared to abstainers.[vi]

Chocolate – peaks at 10g, or about 3 pieces – and let’s say dark, 70%+ thus with less sugar is more likely to be better, as sugar is a strong indicator of cognitive decline.

More recent studies giving cocoa, a rich source of flavanols, have shown improved cognition, possibly by improving circulation.[vii]

Wine – consumption reduced risk up to 125g a day, which is a small glass. A study in the British Medical Journal in 2018 showed that while abstinence increased risk by 48% having more than 14 units of alcohol a week, which is equivalent to a medium glass of wine every day, increases risk.[viii]

Grains and potatoes – reached a plateau at 100 to 150g a day, which is one or two servings max. High fibre bread was the the most beneficial high fibre food and white bread increased risk.

Fruit and veg – although the more you eat the better, benefits start to plateau at 500g a day, which is about five to six servings a day.

Of individual vegetables, carrots, cruciferous vegetables and citrus fruit were the most positive as were mushrooms.

A study in the US found that those who ate 1.3 portions of green leafy vegetables a day, compared to less than one a week, had a dramatically slower decline in cognitive function, equivalent to being 11 years younger over a 10-year period.

Berries are particularly protective, especially blueberries and strawberries.[ix]

Fish – is the most protective. Nurk’s study found a peak benefit at about 100g a day, which is one to two servings.

A study of all the studies by National Institutes of Health researcher, Beydoun, reported that eating fish once or more each week reduces risk of Alzheimer’s by a third compared with those who eat fish less than once a week.[x]

Olive oil and nuts – seem to be positive aspects associated with a Mediterranean diet.[xi]

One study assigned people to a Mediterranean diet supplemented with either a litre a week of olive oil or 30g of nuts a day which is a small handful, versus a control diet with low fat and reported reduced cognitive decline with the extra olive oil or nuts.  [xii]

Protective diets

Early studies on the Mediterranean style diet reported that high adherence versus low adherence reduced risk of Alzheimer’s by a third.[xiii][xiv]

A study which followed 2,000 people over 20 years found that adherence to what they defined as healthy diet – which meant ‘modifying the quality of fats, increasing vegetable consumption, and decreasing salt and sugar consumption’ was associated with a halving of dementia risk.

With the exception of sugar, no individual food predicted risk significantly.[xv]


But the problem with studies like this is the assumptions. In this case ‘modifying the quality of fats’ means using vegetable oils as opposed to margarine or butter and not eating the visible fat on meat.

Vegetable oils is rather vague – it could be olive oil or something like sunflower oil. The assumption is that a low-fat diet might be beneficial, yet a high fat, low carb (HFLC) ketogenic diet appears to be protective.

A study in Holland reported ‘that better diet quality related to larger brain volume, grey matter volume, white matter volume, and hippocampal volume.

High intake of vegetables, fruit, whole grains, nuts, dairy, and fish and low intake of sugar-containing beverages were associated with larger brain volumes.’[xvi]

Helpful information: 

The best way to reduce your risk for dementia or Alzheimer’s is to take positive proactive steps to include in your diet all the things that will do that.

This article gives you that information, and in part two I will share with you what you also need to avoid to further reduce your risk.

[i] Glans I, Sonestedt E, Nägga K, Gustavsson AM, González-Padilla E, Borne Y, Stomrud E, Melander O, Nilsson P, Palmqvist S, Hansson O. Association Between Dietary Habits in Midlife With Dementia Incidence Over a 20-Year Period. Neurology. 2022 Oct 12:10.1212/WNL.0000000000201336. doi: 10.1212/WNL.0000000000201336. Epub ahead of print. PMID: 36224029.
[ii] Eskelinen MH, Ngandu T, Tuomilehto J, Soininen H, Kivipelto M. Midlife healthy-diet index and late-life dementia and Alzheimer’s disease. Dement Geriatr Cogn Dis Extra. 2011 Jan;1(1):103-12. doi: 10.1159/000327518. Epub 2011 Apr 27. PMID: 22163237; PMCID: PMC3199886.
[iii] Nurk E, Refsum H, Drevon CA, Tell GS, Nygaard HA, Engedal K, Smith AD. Intake of flavonoid-rich wine, tea, and chocolate by elderly men and women is associated with better cognitive test performance. J Nutr. 2009 Jan;139(1):120-7. doi: 10.3945/jn.108.095182. Epub 2008 Dec 3. PMID: 19056649.
[iv] Nurk E, Refsum H, Drevon CA, Tell GS, Nygaard HA, Engedal K, Smith AD. Cognitive performance among the elderly in relation to the intake of plant foods. The Hordaland Health Study. Br J Nutr. 2010 Oct;104(8):1190-201. doi: 10.1017/S0007114510001807. Epub 2010 Jun 16. PMID: 20550741.
[v] Feng L, Chong MS, Lim WS, Lee TS, Kua EH, Ng TP. Tea for Alzheimer Prevention. J Prev Alzheimers Dis. 2015;2(2):136-141. doi: 10.14283/jpad.2015.57. PMID: 29231231.
[vi] Cornelis MC, Weintraub S, Morris MC. Caffeinated Coffee and Tea Consumption, Genetic Variation and Cognitive Function in the UK Biobank. J Nutr. 2020 Aug 1;150(8):2164-2174. doi: 10.1093/jn/nxaa147. PMID: 32495843; PMCID: PMC7398783.
[vii] Lamport DJ, Pal D, Moutsiana C, Field DT, Williams CM, Spencer JP, Butler LT. The effect of flavanol-rich cocoa on cerebral perfusion in healthy older adults during conscious resting state: a placebo controlled, crossover, acute trial. Psychopharmacology (Berl). 2015 Sep;232(17):3227-34. doi: 10.1007/s00213-015-3972-4. Epub 2015 Jun 7. PMID: 26047963; PMCID: PMC4534492.
[viii] Sabia S, Fayosse A, Dumurgier J, Dugravot A, Akbaraly T, Britton A, Kivimäki M, Singh-Manoux A. Alcohol consumption and risk of dementia: 23 year follow-up of Whitehall II cohort study. BMJ. 2018 Aug 1;362:k2927. doi: 10.1136/bmj.k2927. PMID: 30068508; PMCID: PMC6066998.
[ix]  Devore E et al, ‘Dietary intakes of berries and flavonoids in relation to cognitive decline’, Annals of neurology 2012; 72: 135-43; Agarwal P, Holland TM, Wang Y, Bennett DA, Morris MC. Association of Strawberries and Anthocyanidin Intake with Alzheimer’s Dementia Risk. Nutrients. 2019 Dec 14;11(12):3060. doi: 10.3390/nu11123060. PMID: 31847371; PMCID: PMC6950087
[x] Beydoun MA, Beydoun HA, Gamaldo AA, Teel A, Zonderman AB, Wang Y. Epidemiologic studies of modifiable factors associated with cognition and dementia: systematic review and meta-analysis. BMC Public Health. 2014 Jun 24;14:643. doi: 10.1186/1471-2458-14-643. PMID: 24962204; PMCID: PMC4099157.
[xi] Román GC, Jackson RE, Reis J, Román AN, Toledo JB, Toledo E. Extra-virgin olive oil for potential prevention of Alzheimer disease. Rev Neurol (Paris). 2019 Dec;175(10):705-723. doi: 10.1016/j.neurol.2019.07.017. Epub 2019 Sep 11. PMID: 31521394.; Salis C, Papageorgiou L, Papakonstantinou E, Hagidimitriou M, Vlachakis D. Olive Oil Polyphenols in Neurodegenerative Pathologies. Adv Exp Med Biol. 2020;1195:77-91. doi: 10.1007/978-3-030-32633-3_12. PMID: 32468462.
[xii] Valls-Pedret C, Sala-Vila A, Serra-Mir M, Corella D, de la Torre R, Martínez-González MÁ, Martínez-Lapiscina EH, Fitó M, Pérez-Heras A, Salas-Salvadó J, Estruch R, Ros E. Mediterranean Diet and Age-Related Cognitive Decline: A Randomized Clinical Trial. JAMA Intern Med. 2015 Jul;175(7):1094-1103. doi: 10.1001/jamainternmed.2015.1668. Erratum in: JAMA Intern Med. 2018 Dec 1;178(12):1731-1732. PMID: 25961184.
[xiii] Singh B, Parsaik AK, Mielke MM, Erwin PJ, Knopman DS, Petersen RC, Roberts RO. Association of mediterranean diet with mild cognitive impairment and Alzheimer’s disease: a systematic review and meta-analysis. J Alzheimers Dis. 2014;39(2):271-82. doi: 10.3233/JAD-130830. PMID: 24164735; PMCID: PMC3946820.
[xiv] Scarmeas N, Stern Y, Tang MX, Mayeux R, Luchsinger JA. Mediterranean diet and risk for Alzheimer’s disease. Ann Neurol. 2006 Jun;59(6):912-21. doi: 10.1002/ana.20854. PMID: 16622828; PMCID: PMC3024594.
[xv] Sindi S, Kåreholt I, Eskelinen M, Hooshmand B, Lehtisalo J, Soininen H, Ngandu T, Kivipelto M. Healthy Dietary Changes in Midlife Are Associated with Reduced Dementia Risk Later in Life. Nutrients. 2018 Nov 3;10(11):1649. doi: 10.3390/nu10111649. PMID: 30400288; PMCID: PMC6265705.
[xvi] Croll PH, Voortman T, Ikram MA, Franco OH, Schoufour JD, Bos D, Vernooij MW. Better diet quality relates to larger brain tissue volumes: The Rotterdam Study. Neurology. 2018 Jun 12;90(24):e2166-e2173. doi: 10.1212/WNL.0000000000005691. Epub 2018 May 16. PMID: 29769374.