If you had to pick one nutrient that has the biggest impact on future risk of cognitive decline and dementia, it’s probably vitamin B12. It is one of the most commonly deficient vitamins, affecting your whole body, from your brain to your bones. The older you are, the more you need, but not necessarily because your brain cells need more as such, but rather because less B12 from food sources gets through into the bloodstream and then into the brain and other organs.
So, on the one hand, we need to have a conversation about the food you eat providing sufficient B12, and, on the other hand, we have to explore why some people don’t absorb enough, and what can be done about this.
The food front is the easy part. As the last email showed you only animal produce provides B12 (meat, fish, eggs and milk). However, there is not always a good correlation between apparent intake from food and blood levels. The B12 in fish and milk seems better absorbed. The easy ‘safety guard’ is to supplement 10mcg a day in an ‘optimum nutrition’ style multivitamin. (The RDA in multis only give 2.5mcg which may not be enough.)
Vegans simply must either supplement or eat foods that are fortified with supplemental B12. There are a lot of myths around certain vegan foods, from blue-green algae to certain fungi providing B12, but there’s a quirk in nature whereby plant derived B12 is subtly different, an analogue of actual B12 needed by humans, and it does work for us.
If you’re vegan do read the Report Vitamin B12 – Why Vegans Need it in your Library.
B12 deficiency, probably more to do with limited absorption than diet, is extremely common among people over the age of 60 but it appears that even levels in the low–normal range may be harmful.
In a study of 61- to 87-year-olds, the lower the level, the greater was the brain size shrinkage. Two in five people over age 61 had a level of B12 that was associated with accelerated brain shrinkage and memory decline. None of these subjects were diagnosed as classically B12 deficient. However, the lower their B12 status, the worse were their memory scores. Less B12 means higher homocysteine levels and the higher a person’s homocysteine level the greater their risk for dementia or Alzheimer’s.
However, low B12 status is rarely properly checked for and there are good grounds for making it a routine test, along with homocysteine, for anyone over the age of 60. This is because its ability to be absorbed becomes worse with age. The usual means of checking is to measure one’s plasma B12 levels, but this is a very crude measure and it is becoming clear that having a level in the low end of the so-called ‘normal’ range is associated with worsening memory.
If your doctor tests your B12 status they’ll probably use a serum B12 test. There are two problems with this test. The first is the so-called ‘normal’ level. It used to be that anything above 150 pmol/l was considered adequate but, in Japan they treat a level below 370pmol/l as too low. Below 400pmol/l is associated with worsening cognition, while above 500 is probably optimal.
The second problem is that up to half of the B12 in your bloodstream becomes ‘bound’ and unavailable for absorption into cells. Serum B12 measures the whole lot – both bound and free/functional B12.
A much more accurate test is called MMA (methylmalonic acid), which is a more reliable marker for B12 deficiency and becomes high if you are deficient. This chemical only accumulates if you are deficient in B12, or not using it efficiently. An MMA test is more widely available.
Another alternative, in fact the best of all which only measures the active B12 in your bloodstream, is called HoloTransCobalamin (HoloTC or HTC) which, if low, indicates deficiency. If your B12 level or HoloTC is low (below 300 pmol/l or 40pmol/l) or MMA above 270 nmol/L or if your homocysteine is above 10mcmol/l, then you are endangering your health.
Occasionally we see ‘rogue’ very high serum B12 levels for no clear reason. If this happens to you, ask for a
homocysteine test and/or an MMA or HoloTC test.
If you’re not sure what yours is and want to find out, in the UK there’s an Essential Health Check home test kit you can buy from YorkTest which is extremely good value. It also tests your serum B12, folate and vitamin D. B12 has no danger of toxicity.
A common sign of B12 deficiency, known as pernicious anaemia, is chronic fatigue. Other tell-tale signs are brain fogs, breathlessness (sighing and gulping), brittle nails with ridges, pins and needles, swollen or sore tongue, balance problems and unsteadiness. These can be experienced by young and old since some people have innate difficulty absorbing vitamin B12. If you do have many symptoms make sure you get tested first. There’s some very good information on the Pernicious Anaemia Society website www.pernicious-anaemia-society.org.
B12 is only found in animal foods, such as meat, fish, eggs and milk. Our advice is to eat more fish and also to supplement at least 10mcg at any age, perhaps up to 50mcg if you are over 50, and 500mcg or more if you have a raised homocysteine level – above 10mmol/l. While none of us ‘need’ 500mcg, these high levels become necessary as absorption of B12 declines. This is to do with a lack of production of intrinsic factor in the stomach. One way to potentially improve B12 absorption is to give a special form of B12, either methylcobalamine or glutathionylcobalamine, which is sometimes used in combination supplements.
The reason for recommending this seemingly very high level, given that the RDA is only 2.5μg, is that only these kind of daily intakes help to correct deficiency. That’s what a group of researchers in Holland found when they investigated how much B12 you need to take in to correct mild B12 deficiency. Only doses of 647 to 1032μg of B12 were associated with correcting deficiency. In their words, ‘the lowest dose of oral B12 required to normalize mild B12 deficiency is more than 250 times greater than the Recommended Daily Amount [2.5μg]’. So much for a ‘well balanced diet’ giving you all the nutrients you need!
