Eating one serving of oily fish a week is associated with halving the risk of Alzheimer’s. Supplements of one kind of omega 3 fish oil, called DHA, have been shown to enhance memory in adults who don’t eat fish, and to prevent memory loss in those in the early stages of memory decline. But it’s not just oily fish. The more fish you eat, the better your memory test performance. Fish is also an excellent source of vitamins B12, D and choline, all essential for the brain. Chia and flax seeds are also an excellent source of omega 3.

Our recommendations

Eat fish at least twice a week, seeds on most days and supplement omega 3 fish oils.

The best fish for Omega 3, the fat that’s linked with improving mood, are: mackerel (1,400mg per 100g/3oz) herring/kipper (1,000mg) sardines (1,000mg),fresh tuna (900mg), anchovy (900mg), salmon (800mg), trout (500mg). Tuna, being high in mercury, is best eaten not more than twice a month. Swordfish and marlin are best avoided or eaten very infrequently for the same reason..

The best seeds are flax seeds and pumpkin seeds. Flax seeds are so small they are best ground and sprinkled on cereal. Alternatively, use flax seed oil, for example in salad dressings. While technically providing omega 3 only about 5% of the type of omega 3 (alpha linolenic acid) in these seeds is converted in your body into EPA.

To help reduce brain inflammation, we recommend supplementing with omega 3 fish oils, as well as eating oily fish twice a week. The ideal amount for maximizing memory and mental health is likely to be in the region of 300 mg of EPA and 200 mg of DHA daily, and double or triple this if you have age-related memory decline.

Also minimise your intake of fried foods.

The more fruit and vegetables you eat the lower is your risk of cognitive decline with vegetables being particularly protective. The best kinds of vegetables are carrots, cauliflower, broccoli, Brussels sprouts, cabbage, spinach and mushrooms. The best fruits are berries, especially blueberries and strawberries. Flavonoids and polyphenols, found not only in fruit and vegetables, but also in tea, red wine and dark chocolate, are associated with preserving memo and a number of mechanisms exist to explain their positive actions on cognitive performance. The most protective effect is found eating six servings (500g) a day of fruit and vegetables.

Supplementing both vitamin C (2g), taken in two divided doses, plus 400iu (300mg) of vitamin E, as part of an all-round antioxidant that contains N-acetyl-cysteine and/or reduced glutathione, as well as Co-enzyme Q10.

Keeping your blood glucose level down preserves your memory. That means avoiding sugar as much as possible and eating slow-releasing ‘whole’ carbohydrate foods such as wholegrain bread or pasta and oat cakes. Eating white bread is associated with a poorer cognitive test performance, whereas high fibre bread is associated with better performance. Eating carbohydrate foods with protein, for example brown rice with fish, or porridge oats with seeds, further reduces the glycemic load (GL) of a meal. Best fruits in this respect are berries, cherries and plums while grapes, raisins and bananas are high GL. These kinds of foods are consistent with a Mediterranean diet which has also been shown to reduce risk. Eat your fruit, don’t drink it. Fruit juice has a lot of sugar in it.

The single, hottest nutritional discovery is that your risk of developing Alzheimer’s is strongly linked to your level of the amino acid homocysteine. The lower your level throughout life the smaller your chances of developing serious memory decline. Homocysteine is a neurotoxin, capable of directly damaging the medial temporal lobe, which is the area of the brain that rapidly degenerates in AD. Homocysteine is easily lowered with inexpensive B vitamins.

Having a higher intake and blood level of vitamin B12 and folic acid is associated with a quarter of the risk of developing Alzheimer’s. Vitamin B6, B12 and folic acid, especially in combination, lower blood levels of homocysteine, which is a key predictor of risk. Lowering your homocysteine, if above 10mcmol/l, by supplementing high dose B6 (20mg), folic acid (800mcg) and B12 (500mcg) has been shown to greatly reduce the rate of brain shrinkage and memory loss in those at risk of Alzheimer’s. That is why it is VITAL to check your homocysteine level and, if above 10, speak with your doctor about supplementing high doses of B vitamins. Otherwise, supplement a daily multivitamin or B complex. B12 absorption can greatly worsen with age, and is inhibited by diabetes medication, and antacid ‘proton-pump inhibitor’ (PPI) medication. If you are taking these be sure your GP checks your homocysteine level. If you are based in the UK, you can also seek out a private testing service such as Medichecks or Biolabs.

While there is inconsistent evidence linking coffee with more or less risk, drinking lots of coffee both raises homocysteine levels and promotes the excretion of protective B vitamins. For example, two cups of coffee raises homocysteine by 11% in 4 hours.

Green tea on the other hand, is associated with a lower risk of cognitive impairment. Ordinary tea drinking is also associated with better cognition. Our advice is to limit coffee to one a day and drink tea, ideally green, instead.

Keeping fit, learning new things to stimulate your mind and staying in touch with friends and family all help to reduce your risk. If you don’t use it you lose it.There may also be a benefit in exercises that require more mind-body coordination, such as t’ai chi or yoga, and exercising outdoors – we make vitamin D in the presence of sunlight. These activities also help to reduce stress, which is another prevention step in the right direction, as is keeping your blood pressure down.