Important Nutrients in the Methionine Cycle

Graphic from the inimitable benbest.com.  GSH is glutathione.

Studies suggest that betaine, along with vitamins B6 and B12 and folic acid, helps reduce higher levels of homocysteine. (This article has lots of citations.)  I think there is now good evidence that the problem with methionine  is really a problem with homocysteine.  Having high levels of homocysteine is related to a higher risk of heart disease and stroke.  Food sources of betaine include beets, broccoli, grains, shellfish, and spinach.  More info on betaine.

Source.

Also note the importance of amino acids like cysteine, glycine, and serine: Cysteine and glycine are converted to glutathione (an important water-soluble antioxidant) with the addition of selenium.  Pea protein and collagen are good sources of glycine, but neither contains much cysteine.  Serine can reduce homocysteine levels, and pea protein is also a good source.

Excess or Insufficient Micronutrients?

Some authors have argued that excess micronutrients, specifically zinc, iron, and copper are a cause of a number of diseases, from atherosclerosis to Alzheimer's. (1) But other writers argue that most Americans are micro nutrient-deficient (very few Americans are macronutrient deficient!). (2)

Micronutrients are critical for human health, but many have relatively narrow ranges associated with optimal health.  Assuming that U.S. dietary guidelines are valid (debatable, but a good starting point), how many people really are receiving inadequate or overabundant micronutrients?

I searched journal articles featuring contemporary data from the U.S. NHANES which surveys a representative sample of the U.S. population.  

Large portions of the population had total usual intakes (food and supplement use) below the estimated average requirement for vitamins A (35%), C (31%), D (74%), and E (67%) as well as calcium (39%) and magnesium (46%). Only 0%, 8%, and 33% of the population had total usual intakes of potassium, choline, and vitamin K above the adequate intake when food and multivitamin use was considered. The percentage of the population with total intakes greater than the tolerable upper intake level (UL) was very low for all nutrients; excess intakes of zinc were the highest (3.5%) across the population of all of the nutrients assessed in NHANES.(3)

Population-based studies indicate that vegetarians have lower mean intakes of vitamin B-12 and zinc and higher intakes of fiber, magnesium, and vitamins A, C, and E than do nonvegetarians. Usual intake data suggest a similar prevalence of inadequacy between vegetarians and nonvegetarians for magnesium and vitamins A, C, and E, with both groups at high risk of inadequate intakes of these nutrients. These same data report that vegetarians have a higher prevalence of inadequacy for iron, vitamin B-12, protein, and zinc than do nonvegetarians. Vegetarians should optimize intakes of vitamin B-12, zinc, and protein; and both vegetarians and nonvegetarians need to increase intakes of calcium, magnesium, fiber, and vitamins A, C, and E. (4)

But these studies only analyze reported food intake, which is notoriously unreliable, even, possibly, in NHANES. Interestingly, NHANES also does actual blood tests, and the results from that research found very few physiologyical (as opposed to dietary) deficiencies.  CDC's National Report on Nutritional Indicators (2012, valid for the period 2003-2006,  only found deficiencies in B6 (11%), Iron (women: 10%), Vitamin D (8%), Vitamin C (6%).   This same report indicates that folate supplementation is responsible for lowering deficiency to less than 1% of the U.S. population.  They also note that many women have iodine levels "bordering on insufficiency".  They did not note any micronutrient excesses. (5)

Sources:

(1) Power Foods for the Brain.  Barnard, Neil.  2013

(2) see, for example, http://chriskresser.com/are-supplements-really-necessary and http://chriskresser.com/why-you-should-think-twice-about-vegetarian-and-vegan-diets

(3) J Am Coll Nutr. 2014;33(2):94-102. doi: 10.1080/07315724.2013.846806.

Multivitamin/mineral supplement contribution to micronutrient intakes in the United States, 2007-2010.

Wallace TC1, McBurney M, Fulgoni VL 3rd. (Affiliation: Council for Responsible Nutrition)

(4) Am J Clin Nutr. 2014 May 28;100(Supplement 1):365S-368S.

Nutritional adequacy of plant-based diets for weight management: observations from the NHANES.

Farmer B.PlantWise Nutrition Consulting LLC

(5) Second National Report on Biochemical Indicators of DIet and Nutrition in the U.S. Population. 2012

Antinutrient Resources

In general, plant secondary metabolites can have positive and negative effects (Weston A. Price). The reason I don't try to categorically avoid them, but treat them with caution, is that these effects are multiplicitious and biological: very hard to predict what they will do, good or bad...

However, unless we know about the problems with antinutrients, we won't know why eating raw flour or dough is dangerous, why green potatoes are toxic, or how many raw red kidney beans it takes to kill a man (not very many).

But on the whole, unless you are allergic, most antinutrients will be digested, and some are actually good for you. For example, this article mentions that inositol hexaphosphate is a break-down product of phytic acid. Most phytic acid is broken down by digestion, and there is evidence that it can have beneficial effects as well as deleterious effects.

This article points out that most sweet potato antinutrients are destroyed by baking, as opposed to boiling. This FAO article on all the major food crops and their antinutrients specifies that " Heating to 90°C for several minutes inactivates trypsin inhibitors", which explains why baked sweet potatoes are nontoxic. (But the article also points out that diseased or moldy sweet potatoes may have toxins that are not completely deactivated by cooking ....moldy vegetables should not be consumed. Apparently, toxins in normal potatoes are also not destroyed by normal cooking methods. Furthermore, sweet potatoes do not have lectins, but normal potatoes do. These compounds can have some antidigestive effects, but most should be destroyed by cooking.

Antinutrients are important, but I think methionine and nutrient density / glycemic index considerations are more important overall. A few potatoes or slices of bread shouldn't hurt most people, but if you have the luxury of chooses less toxic plant products, sweet potatoes and especially squash and pumpkins are some of the best sources of nutrients, with the least amount of antinutrients.

Disturbance is good for productivity

Making a "moder" pine forest a little more like a "mull" prarie....