Could Diet Be Key In The Fight Against Dementia?
Fewer than one in every hundred Alzheimer’s diagnoses are attributed to genes.[i] And Alzheimer’s (which makes up two thirds of dementia) is not an inevitable consequence of ageing. “It is largely a preventable disease, and we know quite a lot about what people need to do to help prevent it,” says Professor David Smith, former Deputy Head of the Faculty of Medical Science at the University of Oxford, who is one of a team of world-leading prevention experts at the Food for the Brain Foundation.
Belle spoke to Patrick Holford, a nutrition and mental health expert, and founder of the Institute for Optimum Nutrition, VitaminC4Covid, and the charitable Food for the Brain Foundation, where he directs their Alzheimer’s prevention project.
The charity focuses on helping people make simple, positive changes – simple steps that will give your brain and memory the best chance of avoiding dementia. Here, Patrick shares what he has learned from his research…
Reduce sugar and refined carbs
Your waistline isn’t the only reason to eat less sugar, sugary junk food, sweetened drinks and white, refined bread, rice and pasta. A 2022 US study reported that having a blood sugar level in the high end of the normal range, at age 35, increased a person’s risk of developing Alzheimer’s later in life by 15%.[ii]
Reduce the amount and frequency of dishes featuring rice, pasta and potatoes, and instead have more beans, fish, chicken. Eat eggs for breakfast or yoghurt, nuts, seeds and berries. Have oats instead of sugary cereals and oat cakes instead of bread. Our sugar expert Professor Robert Lustig, from the University of California, showed that sweet-toothed teenagers already have shrinking brains and worsening memory.[iii] It starts that young.
Boost your intake of omega-3
DHA (Docosahexaenoic acid) is an important omega-3 fatty acid, and it is found in seafood and certain types of algae (good news for vegans).
A study of almost half a million people from the UK’s Bio Bank found that those taking fish oil supplements had a 7% lower risk of dementia[iv]. The same was true for those with higher blood levels. Eating three servings of fish a week cuts Alzheimer’s risk by a third.[v] The best fish are those that swim in cold water and eat other fish – salmon and mackerel. Sardines, anchovies, herring and kippers are also excellent. If you have the taste and the budget for it, best of all is caviar.
Vegans need to seek out algal or seaweed-derived DHA – it is just as good as that found in fish. You need at least 200mg a day, but ideally double this amount. A very small amount of ALA (alpha-linolenic acid) in walnuts, chia and flax seeds, as well as colder climate leafy vegetables, does convert through to DHA so these foods are also important to eat on a daily basis. Edamame beans and kidney beans are also good additions for your diet.
Up your fruit and veg intake
Fruits, vegetables, herbs, spices and cacao are rich in brain-friendly antioxidants and polyphenols which improve circulation in your brain and help keep it young. So, while eating five servings of fruit and veg is generally good advice, having a handful of berries a day (blueberries being the best), and at least four servings of vegetables is better. Cacao in chocolate is also brain-friendly[vi], but the sugar isn’t. Having a cocoa drink, made with cacao powder (without sugar) is the best of both worlds. Spices such as turmeric, cumin and chilli, cayenne or paprika are also great sources of polyphenols.
Supplement B vitamins
The first study that showed a reversal in the rate of brain shrinkage in people with pre-dementia gave a supplement of vitamin B6, B12 and folic acid. The study showed that the B vitamins halved the rate of brain shrinkage, cut the shrinkage in the Alzheimer’s areas of the brain by nine times.[vii] The best drug to date has cut brain shrinkage by 2% with virtually no clinical benefit.
B vitamins are needed to help attach omega-3 into your brain. The next big breakthrough came when Professor David Smith’s group at Oxford University showed that the omega-3 fats don’t work nearly so well without B vitamins – and the B vitamins don’t work in people with low intake of omega-3. You need both.
“In those with sufficient omega-3 status B vitamins resulted in up to 73% less brain shrinkage and slowed memory decline,”[viii] says Professor Smith. One in three ended the trial with no clinical signs of dementia at all. Two other trials, in the Netherlands[ix] and Sweden[x], have confirmed that omega-3 and B vitamins are a dynamic duo, slowing down cognitive decline when both are sufficient.
The three critical B vitamins are vitamin B6, B12 and folic acid or folate which is found in green foods (think foliage). We recommend that older people supplement at least 10mcg of vitamin B12 a day, but the study gave 500mcg. Why? Because many older people absorb B12 less well. It needs stomach acid so those on antacid drugs often end up lacking B12.[xi]
The US National Institutes of Health researchers attribute 32% of risk to inactive lifestyle, 22% to smoking, 22% to lack of seafood or omega-3 and another 22% to a raised blood homocysteine level, which is a measure of B vitamin status.[xii]
Activity and rest
A study on trainee London taxi drivers learning ‘The Knowledge’—which involves memorising 26,000 streets – found that those who passed, compared to those that failed had literally built more brain tissue and connections.[xiii]
You don’t need to do ‘The Knowledge’, but your brain des need exercise. This can be solving puzzles, mastering a musical instrument or learning a new language. It’s especially good to tackle things you’re bad at.
But rest is as important as activity, the quantity and quality of sleep makes a big difference. Sleeping only five hours, or nine or more hours, doubles dementia risk.[xiv] The optimal sleep duration is 7 hours and the optimal time for going to sleep is 10pm.
Risk for Alzheimer’s can be picked up in mid-life. That sounds like bad news, but it isn’t, because most people can cut their risk by two thirds just by making a few relatively simple diet and lifestyle changes in mid-life.
[1] Bekris LM, Yu CE, Bird TD, Tsuang DW. Genetics of Alzheimer disease. J Geriatr Psychiatry Neurol. 2010 Dec;23(4):213-27. doi: 10.1177/0891988710383571. PMID: 21045163; PMCID: PMC3044597. [1] Zhang X, Tong T, Chang A, Ang TFA, Tao Q, Auerbach S, Devine S, Qiu WQ, Mez J, Massaro J, Lunetta KL, Au R, Farrer LA. Midlife lipid and glucose levels are associated with Alzheimer’s disease. Alzheimers Dement. 2022 . doi: 10.1002/alz.12641. Epub ahead of print. PMID: 35319157. [1] Yau PL, Castro MG, Tagani A, Tsui WH, Convit A. Obesity and metabolic syndrome and functional and structural brain impairments in adolescence. Pediatrics. 2012 Oct;130(4):e856-64. doi: 10.1542/peds.2012-0324. Epub 2012 Sep 3. PMID: 22945407; PMCID: PMC3457620. [1] Yu JT et al, Circulating polyunsaturated fatty acids, fish oil supplementation, and risk of incident dementia: a prospective cohort study of 440,750 participants, BMC medicine (pending publication) [1] Kosti RI, Kasdagli MI, Kyrozis A, Orsini N, Lagiou P, Taiganidou F, Naska A. Fish intake, n-3 fatty acid body status, and risk of cognitive decline: a systematic review and a dose-response meta-analysis of observational and experimental studies. Nutr Rev. 2022 May 9;80(6):1445-1458. doi: 10.1093/nutrit/nuab078. PMID: 34605891. [1] Smith AD, Smith SM, de Jager CA, Whitbread P, Johnston C, Agacinski G, Oulhaj A, Bradley KM, Jacoby R, Refsum H. Homocysteine-lowering by B vitamins slows the rate of accelerated brain atrophy in mild cognitive impairment: a randomized controlled trial. PLoS One. 2010 Sep 8;5(9):e12244. doi: 10.1371/journal.pone.0012244. PMID: 20838622; PMCID: PMC2935890. [1] Smith AD, Smith SM, de Jager CA, Whitbread P, Johnston C, Agacinski G, Oulhaj A, Bradley KM, Jacoby R, Refsum H. Homocysteine-lowering by B vitamins slows the rate of accelerated brain atrophy in mild cognitive impairment: a randomized controlled trial. PLoS One. 2010 Sep 8;5(9):e12244. doi: 10.1371/journal.pone.0012244. PMID: 20838622; PMCID: PMC2935890. [1] JeJernerén F, Elshorbagy AK, Oulhaj A, Smith SM, Refsum H, Smith AD (2015). Brain atrophy in cognitively impaired elderly: the importance of long-chain ?-3 fatty acids and B vitamin status in a randomized controlled trial. Am J Clin Nutr. 2015 Jul;102(1):215-21 [1] van Soest, A.P.M., van de Rest, O., Witkamp, R.F. et al. DHA status influences effects of B-vitamin supplementation on cognitive ageing: a post-hoc analysis of the B-proof trial. Eur J Nutr (2022). https://doi.org/10.1007/s00394-022-02924-w [1] Jernerén F, Cederholm T, Refsum H, Smith AD, Turner C, Palmblad J, Eriksdotter M, Hjorth E, Faxen-Irving G, Wahlund LO, Schultzberg M, Basun H, Freund-Levi Y. Homocysteine Status Modifies the Treatment Effect of Omega-3 Fatty Acids on Cognition in a Randomized Clinical Trial in Mild to Moderate Alzheimer’s Disease: The OmegAD Study. J Alzheimers Dis. 2019;69(1):189-197. doi: 10.3233/JAD-181148. PMID: 30958356. [1] 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. [1]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. [1] Woollett K, Maguire EA. Acquiring “the Knowledge” of London’s layout drives structural brain changes. Curr Biol. 2011 Dec 20;21(24):2109-14. doi: 10.1016/j.cub.2011.11.018. Epub 2011 Dec 8. PMID: 22169537; PMCID: PMC3268356. [1] Bubu OM, Brannick M, Mortimer J, Umasabor-Bubu O, Sebastião YV, Wen Y, Schwartz S, Borenstein AR, Wu Y, Morgan D, Anderson WM. Sleep, Cognitive impairment, and Alzheimer’s disease: A Systematic Review and Meta-Analysis. Sleep. 2017 Jan 1;40(1). doi: 10.1093/sleep/zsw032. PMID: 28364458; see also Sabia S, Fayosse A, Dumurgier J, van Hees VT, Paquet C, Sommerlad A, Kivimäki M, Dugravot A, Singh-Manoux A. Association of sleep duration in middle and old age with incidence of dementia. Nat Commun. 2021 Apr 20;12(1):2289. doi: 10.1038/s41467-021-22354-2. PMID: 33879784; PMCID: PMC8058039.
