Brain health: Food notes

A notebook of interesting and valuable information about important foods

Introduction

This constantly growing compendium of information about important foods, food groups, and other nutrients, is make available to website visitors in spite of the fact that major sections are not complete. I have been interested for a long time in learning about wise nutritional practices, and have recenty begun compiling notes on specific foods, based on reliable sources, which I cite here in the Notes and References sections.

No attempt will be made to offer a complete picture of any food, but sources of valuable additional information, when known, will be listed. Note that this is not a list of recommended foods or nutrients. It’s simply a collections of notes. However, all of the core foods will appear here, eventually. A food or nutrient has notes here because I think it’s important to know about it, for one reason or another.

Finally, everything I have notes on will appear on this page, but the items about which I have collected substantial information will have links to a separate page containing that information. See Carbohydates for an example of this.

Beans

(under development)

Blueberries

(under development)

Broccoli

(under development)

Caffeine

(under development)

Carbohydrates

See Glycemic index and the digestible carbohydrates.

Coffee

(under development)

Cranberries

(under development)

EGCG (epigallocatechin gallate)

A polyphenol found in some plants, it’s one of the condensed tannin catechins, and also one of the strongest antioxidants. It appears likely to have impressive anticarcinogenic properties. It protects the heart and arteries from oxidative damage, and may have similar benefits when applied topically to the skin.

Green tea is a major source – optimal doses of EGCG are obtained from four cups of green tea a day¹⁰ (And what about black tea? I cannot say – I haven’t found a source of information on this yet. I assume it’s about the same for this type of tea.)

Five-spice powder

(under development)

Flavonoids

(under development)

Juices, fruit

(under development)

Oats

(under development)

Oils

(under development)

Oranges

(under development)

Polyphenols

(under development)

Pumpkin

(under development)

Salmon, wild

(under development)

Soy

(under development)

Spinach

(under development)

Sugar

One of the two classes of carbohydrates, naturally occurring sugars are relatively rare, which means that for most of human evolution they have been a minor-to-nonexistent factor in our diets. The rise of the food industry has changed this dramatically.

Babies appear to have a natural liking for sugar – all other “tastes” appear to be learned¹⁶. That we should naturally like sugar makes sense – in the sequence of chemicals which begin with photosynthesis, it is the nutrient closest to the most basic energy source of all: solar light (see carbohydrates).

Glucose

This most basic of sugars (see carbohydrates) has very high glycemic index: 100¹⁹.

Fructose

A naturally-occurring sugar (seen mostly in fruits), fructose has also become a major factor in our diets through the wide-spread use of high-fructose corn syrup (HFCS) in manufactured foods, where its use is very widespread. It has a very low glycemic index: 23¹⁷.

HFCS is much loved by the food industry for a couple of reasons: it is cheaper to make than sucrose¹⁸, and it does not much affect one’s hunger. This last factor is critically important. “None of the normal controls on appetite is triggered when you eat foods containing or beverages containing high-fructose corn syrup”¹⁹.

Naturally occurring fructose almost always occurs in conjunction with fiber, micronutrients, and other factors which act to slow digestion and decrease appetite. Pure added fructose, on the other hand, does none of these things. As it doesn’t satisfy hunger, we eat more of a food containing it, until the sheer volume of food consumed acts to moderate our hunger. This is a good thing only if one is selling a food containing HFCS!

Fructose in HFCS is actually absorbed by your body more quickly than sucrose. Insulin isn’t needed to get it into cells, but once there it metabolizes into chemical precursors of cholesterol and triglycerides. Your blood cholesterol increases, and your liver starts to malfunction, which lowers your metabolism. Consumption of HFCS leads to fatty livers and blood cholesterol problems, and may in fact be the main cause for the increase in blood cholesterol levels seen in the USA in recent years¹⁹.

High levels of fructose can be problematic to health in other ways. It can lead to severe liver damage, serum triglycerides, and other problems affecting circulatory system health²⁰.

Sucrose

A sugar composed of one molecule of glucose linked to one molecule of fructose. It has a glycemic index of 65, midway between that of the two sugars of which it is composed¹⁹.

With some popular nutrition writers, there is a considerable bias against sucrose (most commonly encountered as “white” sugar, but also including brown sugar, etc.). The problem, however, lies not with sucrose but with the amounts consumed, and the fact that it is used to induce people to consume foods containing other nutrients (such as fats and other sources of calories, for example) in unhealthy quantities¹⁷.

Tannin

(under development)

Tea

Description

Tea is a drink made from steeping in hot water the leaves of a perennial shrub which is a member of the camelia family. It’s native to south China and north India, but is now cultivated in many places in the world.

There are two large classes of tea tree: Camellia Sinensis and Camellia Assamica.

• Sinensis is smaller, more a bush than a tree, with small leaves. It is native to the mountains of south China. It has a lighter, more flowery taste.
• Assamica is larger, more a small tree than a bush, with larger leaves. It is native to a region of northeastern Indian right below the Himalayan foothills. Most commercial teas come from this variety, which produces a richer, more earthy flavor of tea¹.

While cultivation methods vary by region, processing methods result in three general types of tea²:

• Green (non-oxidized)
• Oolong (semi-oxidized)
• Black (oxidized)

Tea is made from the bud and first 2-3 leaves of a branch, picked every 1-2 weeks. How old the leaf is when picked is one key factor in the type of tea to be made from it, as chemical composition of the leaf changes with age¹.

Health benefits

Tea is very popular in many parts of the world, which means that a lot of money is made from it. Health claims for tea (especially by those who sell it) certainly encourage this trade. Be cautious about these claims, as they usually are not documented, so you are unable to evaluate them. The degree of certainty³ we may have for these claims varies with the claim.

One major problem with the health benefits claimed for tea is that virtually all of the studies are correlational rather than experimental. They show that healthy people drink tea, rather than demonstrating that drinking tea makes people healthy. The latter well may be true, but it has not been demonstrated in the scientific literature. Still, the epidemiological studies are compelling to many informed readers. There is a broad consensus among many thoughtful nutritionists, physicians, and others, that tea has distinct health-supporting benefits.

Choosing a tea

Which type of tea is best, from the point of view of health promotion? Green tea appears to be somewhat higher in valuable nutrients, but the difference is not dramatic. Finding a tea that you can consume regularly is more important than pursuing one particular type⁴.

Nutrients in tea – and how much to drink

Tea is chemically complex, but the main ingredients known or suspected to have benefit are small in number:

• polyphenols, especially EGCG.
• caffeine

How much do you need to drink to be beneficial? See the article on “EGCG”#egcg.

Preparation

Water. Most generally, water is recommended to be boiling before being used to steep tea, but this is not the best practice for green tea and some other forms (“white” teas, for example). For reasons of taste, I virtually always use water that I’ve allowed to sit (in a large bottle) for 12-24 hours, so the chlorine in it can leave the water.

Steeping. Steeped tea is better for you than instant tea. Steeping times which work best vary by type and brand of tea, but in general water temperatures and steeping times should be closely monitored, so as to get the best tasting, most nutritious brew. In general, you should brew tea for at least 3 minutes, then (if using bagged tea) squeeze the bag into your tea, to at least double the polyphenols you’ll be drinking. Some of the nutrients in tea degrade as time passes, so drink your tea freshly brewed⁵.

At some point, usually somewhat after 5 minutes, some teas start to taste tannic (a kind of bitter/tart taste), from the tannic acid released by over-brewing. Some people don’t like this, others do. Lower brewing temperatures and short times can largely prevent this problem. I’ve found that green teas, as well as black teas, vary considerably in the degree to which they release tannins if over-brewed. I don’t like tannin’s taste, and have therefore come to prefer Japanese green tea and Chinese black tea.

Add milk? No. A German study has shown that adding milk to tea (black tea, in the study, but by inference this applies to all teas) prevents the beneficial effects it has on the circulatory system. Only a small amount of milk was required to do this¹³. The problem appears to be that certain milk proteins bind up the critical polyphenols in the tea and make them unavailable for use by the body. This appears to affect only the polyphenols in tea¹⁴.

It’s therefore probably best to keep your tea-drinking quite separate from your consumption of any milk product. (I allow two hours to pass on either side of my tea drinking before consumption of anything containing milk protein – obviously this includes cheeses and yogurt).

Green tea

Green tea is not processed with oxidation, as is the case in varying degrees with other forms of tea. It is only minimally oxidized in processing⁶. It is especially popular in Japan, and increasingly so in the West, for health reasons.

Brewing temperature

It is widely recognized that green tea needs to be brewed at a lower temperature than other teas. Ito En, one of the largest exporters of Japanese green tea, recommends a brewing temperature of 176F (80C) for green tea.

To routinely obtain water of this temperature one can use either of these methods. (I assume here that you’re making 2 cups – 1 pint – of tea, the usual amount I make. Adjust the amount to fit your needs):

• Experiment with your microwave to discover how much time it takes to produce this temperature with a given amount of water. (My old one takes 6 minutes to heat 2 cups to this temperature).)
• To 1.5 cups boiling water add 1/2 cup room temperature (70F) water, and stir.

Brewing time

Recommendations vary (generally from 2 to 6 minutes), but I find that two variables determine the brewing time I use:

• My desire to get the maximum benefit possible from the tea. I assume that the longer one brews the tea the better. Some people simply leave the tea in the pot or cup, after brewing, as they sip the tea. I brew generally for at least 6 minutes, then dunk the tea bags (I use 2 for a pint of tea) in and out of the water a number of times, to “wash” the leaves well, and then finally give the bag a couple of firm squeezes before discarding it. The result is a cloudy, rich tasting tea, with a green residue in the bottom – drink that, too!.
• How easily the tea may be over-brewed.Tea varies considerably in its tannin content. I don’t much like the taste of tannin, but can tolerate low amounts. For a given variety or brand of tea, once I discover the optimum brewing time to prevent too much tannin, I stop brewing at that point. Japanese green tea seems least likely to become tannic in taste – at least in my experience.

Nutrients provided in green tea

• antioxidant EGCG (epigallocatechin gallate): optimal doses are obtained from four cups of green tea a day⁷.
• vitamin K: tea is an unusually strong source⁸.

Health benefits claimed

There is dispute about the health benefits of green tea. Its polyphenols are claimed to have a number of benefits.

Cancer risk reduction

The US FDA, in May 2006, said that “…green tea likely does not reduce breast, prostate or any other type of cancer risk”⁹. This is disputed by Weil, Pratt & Mathews and many other highly reputable authorities¹⁰. The reason for the dispute appears to be simple: the FDA is talking about effects validated by controlled clinical experiments – the highest sort of scientific support. We don’t have much of that for tea, yet. Weil and others, on the other hand are talking about what is quite likely, given extensive epidemiological (population study) findings.

Heart disease risk reduction

On 2006.05.10 the US Food and Drug Administration refused to allow labeling to make this claim, stating that a review of 105 research reports failed to substantiate the claim¹¹. Again, credible authorities take a different view, and apparently for the same reason as with the cancer risk reduction question.

Oolong tea

This is a type of processed tea which has some of the flavors of green tea, but lacks the “grassy” taste and smell often found in green tea. It also lacks the floral smell of black tea.

Central to the processing of tea into Oolong is a partial oxidation of the leaf – it is slightly bruised, then allowed exposure to the air to dry. (Black teas are significantly more oxidized than this.)¹²

Black tea

Usually referred to as “red” teas, in Asia, these are more oxidized, stronger flavored, and darker when brewed, than either green or oolong teas. It also retains its flavor longer, and produces more caffeine when brewed, which makes it ideal for the tea trade. It has long been the most popular tea in the West.

More information

An excellent starting point is this¹.

Tomatoes

(under development)

Turkey (skinless breast)

(under development)

Walnuts

(under development)

Yeast, brewer’s

(under development)

Yogurt

(under development)

Notes

¹ N.A. (2007).

² N.A. (2007a).

³ For a discussion of the problem of uncertainty in assertions – about health and everything else – may be found in Levels of knowing: A scale for assessing uncertain assertions.

⁴ Pratt, S., & Matthews, K. (2004), p. 155.

⁵ Pratt, S., & Matthews, K. (2004), p. 159.

⁶ N.A. (2007b),

⁷ see Weil, A. (2000), p. 138, Pratt, S., & Matthews, K. (2004), p. 157.

⁸ Weil, A. (2000), p. 129..

⁹ Associated press (2006).

¹⁰ Weil, A. (2000), p. 138, Pratt, S., & Matthews, K. (2004), pp. 153ff.

¹¹ Associated press (2006a).

¹² N.A. (2007c), N.A. (2007b).

¹³ Minerd, J. (2007).

¹⁴ N.A. (2007d).

¹⁵ Weil, A. (2000), p. 138.

¹⁶ Weil, A. (2000), p. 59.

¹⁷ Weil, A. (2000), p. 53.

¹⁸ Weil, A. (2000), pp. 62-63

¹⁹ Hyman, M. (2006), pp. 97-98.

²⁰ Weil, A. (2000), pp. 62-63.

References

Associated press. (2006). FDA rejects green tea health claims – No credible evidence that drinking it reduces heart disease risk. Downloaded 2007.01.06 from http://www.msnbc.msn.com/id/12718769

Hyman, M. (2006). Ultra-metabolism – the simple plan for automatic weight loss. New York: Scribner.

Minerd, J. (2007). For Vascular Benefit of Black Tea, Hold the Milk. Downloaded 2007.01.10 from http://www.medpagetoday.com/PrimaryCare/DietNutrition/tb/4826

N.A. (2007). Camellia sinensis. In Wikipedia, The Free Encyclopedia. Downloaded 2007.01.06 from http://en.wikipedia.org/wiki/Camellia_sinensis

N.A. (2007a). Tea Classification. Downloaded 2007.01.06 from http://greentealovers.com/greenteaclassification.htm

N.A. (2007b). Green tea. In Wikipedia, The Free Encyclopedia. Downloaded 2007.01.06 from http://en.wikipedia.org/wiki/Green_tea

N.A. (2007c, November 9). Black tea. In Wikipedia, The Free Encyclopedia. Downloaded 14:35, November 13, 2007, from Green tea. (2007, November 12). In Wikipedia, The Free Encyclopedia. Retrieved 14:38, November 13, 2007, from http://en.wikipedia.org/w/index.php?title=Green_tea&oldid=303761760

N.A. (2007d, January 9). Milk in tea ‘blocks health gains’. Downloaded 2007.11.12 from http://news.bbc.co.uk/2/hi/health/6241139.stm

Pratt, S., & Matthews, K. (2004). Superfoods: Fourteen foods that will change your life. New York: Morrow.

Weil, A. (2000). Eating well for optimum health. New York: Knopf.