QUESTION: I was listening to a health guru-type guest on a radio talk show recently and when a listener called in and asked her opinion on the blood-type diet she scoffed. She claimed that horses, for instance, have at least 12 blood types but they all consume the same foods. I know people aren't horses but humans are animals, ultimately. I don't have the research background to respond to her criticism. Can you help?

ANSWER: Your critic doesn't have the actual number of blood groups in the horse correct and I would expect under these circumstances that the basis of blood group effects in human (gene linkage) might be as lost to her as well.

There are eight recognized blood groups in the horse: A, C, D, K, P, Q, T, and U. (These are similar to A, B, AB, and O groups found in humans). However, unlike our blood types, each of the horses' blood groups can exist in one of several forms. For example, to say that a horse has type A blood is not enough because type A may mean type aA1, type aA', type aH, type aA'H, or type a. And, in addition to having a blood type from the A family, a horse may also have a type from each of the other seven groups.

Almost all species (including even primitive life forms such as bacteria and parasites) have some blood group expression; however they vary greatly in the degree of genes linked to ABO that convey any physical variations.

This is where the effects of blood group in humans places them in a special category: ABO genetics influence stomach acid and intestinal enzyme production probably because their levels are linked to the ABO gene locus, but this is probably a specific linkage found only in humans.

Since the gene for blood group is found on entirely different chromosomes in various animal species, one could only expect that differences in physiology linked to blood group would be different as well. A black colored hair coat is found in many pigs who are group O blood; obviously this is not a phenomena shared with humans.

I am a Type O university professor recently diagnosed with DVT. A subsequent test showed that I was born with a gene mutation that gives me a lifetime propensity for blood clots. My hematologist told me that I would have to take coumadin the rest of my life. I'm not thrilled about this, but so far have been unable to locate any healthier alternatives to the main ingredient in rat poison! Do I need to modify the Type O lifestyle while taking coumadin? Thanks for your help.

One of my teachers, John Bastyr, used to say that the juice of 5 lemons equaled a pharmacologic dose of anti-coagulants.

New research into deep vein thrombosis (DVT), the so-called 'economy class syndrome', has found that lemon juice significantly reduces the likelihood of clots forming during long haul flights.

Japanese researchers who were examining the blood thinning properties of lemons discovered that blood circulates nearly 20% faster at altitude after the juice of a large lemon has been consumed.

The researchers, from Tokai Gakuen University in Nagoya, revealed their findings at a meeting of the Japanese Society for Food Science and Technology. They gave volunteers on long haul flights a drink containing lemon juice. The blood in the volunteers' veins moved 19% faster than that of others on the same flight, thereby reducing the likelihood of potentially fatal clots forming in their systems.

The scientists believe that the effect is due to two ingredients contained in lemon juice - citric acid and lemon polyphenol. They are now recommending that passengers on long haul flights have a lemon drink every five hours to obtain the juice's protective effect.

Grape juice may also be effective, although orange and grapefruit juice apparently are not.

QUESTION: Someone told me that the whole blood type diet theory is racist and that the majority of your information comes from research done during the times of Nazi Germany. Is this true?

ANSWER: In all of my trolling through the scientific literature on blood groups since 1910 I've not recovered a single reference on ABO blood group that supported any of the racial notions then in vogue in Nazi Germany. My suspicion is that if any research was done the results were not supportive of their racist prejudices- i.e. the subjects were more alike on a blood group basis than they would have liked to admit.

Far from being driven by any sort of racist tendencies, the early blood group researchers cast a bright tolerant light during a time of segregation, Jim Crow and rampant anti-Semitism.

One of the primary blood type/ anthropology sources I've cited, Frank Livingstone, even rejected the concept of race altogether. He pointed out that although it is true that there is biological variability between the populations of organisms which comprise a species, this variability does not conform to the discrete packages we call 'races'. In other words, there are no races, the are only clines (a 'cline' is a gradient of physiological change in a group of related organisms usually along a line of environmental transition).

Livingstone suggested that the variability in the frequency of any gene does not utilize the concept of race. (1)

William Clouser Boyd, blood type anthropologist, science fiction writer with Isaac Asimov and the discoverer of lectins (talk about a life!) used his work with blood types in Races and People to demolish the racist notions then commonly believed in this country during the 1950's.(2)

Fifty years later John H. Jenkins could still write of Races and Peoples:

Asimov, as an unabashed liberal and champion of the essential value of any human being (partly because of his growing up as a Jew in an era when significant portions of the world found anti-Semitism innocuous or even virtuous), here attacks the notion of "race". He shows how it is hard to define and uses Boyd's research to demonstrate that the superficial characteristics which so many of us use to define "race" and determine our value vis-a-vis other human beings are utterly without value. In the end, again following Boyd, he resorts to blood typing as a method” not to determine race” but to trace the different overall "types" of humanity and show how they have moved back-and-forth across the world. This is truly a book which ought to be read much more today. I speak as one who has unabashedly absorbed many of Asimov's liberal values.

Boyd defined race as "not an individual, not a single genotype, but a group of individuals more or less from the same geographical area (a population), usually with a number of identical genes, but in which many different types may occur." For Boyd, as with Livingstone, you got your racial characteristics from where you live more than from your genes, and this explained why the variability made the notions of race untenable.(3)

Rather than being racists themselves, I think we should consider the early blood group researchers rare beacons of tolerance in a world still coming to grips with the notion of equality for all.

1.Livingstone FB. 1962 On the non-existence of human race. Current Anthropology 3 (3):279-281.
2.Boyd WC and Asimov I. Races and People. Abelard-Schuman 1955
3.Boyd WC. 1952 The Contribution of Genetics to Anbthyropology. in Anthropology Today, ed. by A.L. Kroeber, pp488-506, Chicago: University of Chicago Press

QUESTION: I have been reading some information by a group that advocates an all or mostly all raw vegetarian diet. In telling of the ills of meat they mention the build up of uric acid in the colon which will eventually lead to disease. I am a type O. Will a type O have this problem with uric acid.

ANSWER: You can read nutritional information of virtually any opinion on essentially any subject. Remember, that is the power of our polymorphism paradigm: It allows us to filter out the excessive rant of 'cure all's' and further reductionist statements.

A quick check of MEDLINE showed no studies indicating that a high protein diet in appropriate circumstances (i.e farm raised, chemical free meat) led to any rise in uric acid levels in the intestines. On the contrary, there is actually more speculation that low uric acid levels may be associated with higher risks for cancer (1) although even this has been disputed (2).

I suppose if you ate a diet of exclusively of meat you could theoretically raise your intestinal level of uric acid, but that diet is impossible to consume, and the vegetables and fruits abundantly found in the type O diet themselves modulate levels of urates and uric acids (3).



1. Mazza A, Casiglia E, Scarpa R, Tikhonoff V, Pizziol A, Sica E, Pessina AC. Predictors of cancer mortality in elderly subjects. Eur J Epidemiol. 1999 May;15(5):421-7.

2. Hiatt RA, Fireman BH. Serum uric acid unrelated to cancer incidence in humans. Cancer Res. 1988 May 15;48(10):2916-8.

3. Jenkins DJ, Popovich DG, Kendall CW, Rao AV, Wolever TM, Tariq N, Thompson LU, Cunnane SC. Metabolic effects of non-absorbable carbohydrates. Scand J Gastroenterol Suppl. 1997;222:10-3.

QUESTION: I want to know what a good source of lycopene is, since tomatoes are forbidden on the A diet.

ANSWER: It should also be remembered that tossing a tomato into your salad is not going to give you all that much lycopene. Tomatoes have a very high water content, so not surprisingly you only find high concentrations of lycopene in tomato paste. You also find large amounts of tomato lectin in tomato paste.

Research confirms that lycopene from tomatoes is absorbed much better into the bloodstream if it is first processed.OK, now for the good news: Lycopene is found in a number of other foods in addition to tomatoes. Let’s take a look: 

There is some evidence that Texas Red Grapefruit has the highest lycopene content of all commercially available grapefruit. As you can see from the chart, raw tomato does not place very high.