Tässä tammikuun loppupuolella Jack Norris on kirjoitellut mielestäni useammankin hyödyllisen tekstin, joten laitan niitä omaan ketjuunsa, johon voi sitten jatkossakin laittaa vastaavia. Toki vanhempiakin voi kaivella.
Riittävästä B12-annoksesta (eriyisesti vähän iäkkäämmillä) ja syanokobalamiinin toimivuudesta:
The takeaway messages:
1. Even in people 65 years and older, cyanocobalamin worked in only two weeks time.
2. It might be a good idea to increase B12 recommendations for people 65 and older to 500 µg per day, rather than the 25 to 100 µg per day that I recommend for all adults.
3. Cyanocobalamin was effective even for ex-smokers. There were not enough current smokers in the study to determine the effectiveness for them.
Tuossakin sivutaan B12-aihetta:
Sitten A-vitamiinista kasvisruokavaliossa:
Sieltä vähän Jackin omia kokemuksia mahdolliseen puutokseen liittyen:
I recently became more concerned about vitamin A, quite literally, by accident. Early last Fall, I twice got up in the middle of the night and walked straight into my bedroom door that was halfway open, face-first!
Over the previous year or so, I had slacked off on vitamin A, relying only on a bit of shredded carrots on salad and mangoes on most days. In mid-November, I decided I needed to make a real effort to add more yellow vegetables to my diet and started eating sweet potatoes every day. A few weeks later, I realized that I had been having no trouble seeing the bedroom door at night. I wondered if there was a connection to what seemed to be my improved night vision.
In checking out whether it was likely that my apparent change in night vision was possibly caused by eating more beta-carotene, I was reminded that vitamin A metabolism is involved with immune function. When vegans get sick easily, I tell them to think about more zinc or protein, neglecting any concern about vitamin A. (Interestingly, vitamin A metabolism appears to rely on zinc.)
Vitamin A deficiency symptoms begin with night blindness, and if it progresses, can lead to the more severe eye problems of corneal ulcers, scarring, and blindness (2). Vitamin A is also important for growth and development in infants and children, and for red blood cell formation (2).
Itse en ainakaan ole havainnut mitään hämäränäön heikkenemistä. Päinvastoin, uskoisin, että se on tässä vuosien rullatessa ennemmin hieman parantunut. Toki sitten syönkin huomattavasti enemmän näitä kasveja kuin Norris aikoinaan tekstinsä perusteella teki. Ilmeisesti elimistön kyky valmistaa A-vitamiinia esiasteista on myös hyvinkin yksilöllistä.
Norris kirjoitteli vähän aikaa sitten myös liotuksen sekä kypsennyksen hyödyllisyydestä liittyen haitallisten yhdisteiden vähentämiseen palkokasveissa ja pähkinöissä. Pähkinöiden suhteen juttu on pikkuisen arvailun varassa, mutta palkokasveihin liittyen hyvää asiaa.
Sieltä vähän summausta:
The first review said that ten hours of incubating California small white beans at 140°F (60°C) resulted in an almost complete loss of phytic acid, with 75% being hydrolysed (broken into phosphorus and inositol) and 25% being diffused into the water. Germination reduced phytic acid by over 60% in garbanzo beans and over 40% in soy beans. Boiling reduced phytic acid in soybeans by 40%. Soaking for 12 hours in room temperature water reduced phytic acid by 7.7, 8.1, 13.2, and 19.1%, respectively, for black-eyed beans, red kidney beans, mung beans, and pink beans. Soaking for 18 hours reduced it by 52.7, 69.6, and 51.7% in pinto, Great Northern, and red kidney beans. So, as far as legumes go, soaking for 18 hours appears to be fairly effective at reducing phytic acid levels (1).
Another review (2) showed that soaking maize for 24 hours reduced phytic acid by about 50%, with most of the reduction occurring in the first hour. It said that soaking also removes other anti-nutrient factors such as saponins, trypsin inhibitors, and polyphenols.
Given the above, I would say that if nuts are high in phytic acid, soaking is likely to reduce it. And because vegans’ zinc intakes tend to be marginal, increasing the zinc absorption from nuts would be great. Personally, I prefer to just take a supplement with zinc to make sure I get enough rather than worrying if I’m absorbing enough from the food I eat.
Soaking reduces the amount of oligosaccharides in beans. But how does it compare to simply cooking? Unfortunately, in the time I had to search, I did not find a study that compared soaking and cooking to only cooking. But I did find a study that compared the oligosaccharide reduction in pinto beans among different preparation methods (1):
- Soaking for 18 hours: 10% reduction
- Soaking for 18 hours, then boiling for 90 minutes: 50% reduction
- Soaking for 18 hours, then autoclaving for 30 minutes: 57% reduction
Autoclaving is approximately the same as pressure-cooking.
It should also be noted that in their comments, the authors of the study above say, “Soaking of Great Northern, kidney, and pinto beans and their subsequent boiling for 90 min decreased the amount of [the oligosaccharides] raffinose and stachyose by 70-80%. In marked contrast, sucrose, raffinose, stachyose, and verbascose contents increased [emphasis added] following the cooking of red, Bengal, black, and green grams (1).”
"Grams" tarkoittaa tässä yhteydessä ilmeisesti linssejä.