I remember seeing this the other day...
www.pdsa.org/about-itp/warnings.html
Herbs, Food, and Supplements
Some food, herbs, and supplements can reduce the number of platelets for various reasons. This list includes those substances that have been documented in journal or other articles. It is not known whether there are few items in this category or if they are underreported. If your platelets drop after taking something new, please notify your doctor.
alcohol3 (also called ethanol-induced thrombocytopenia)
aspartame (NutraSweet)5
cow’s milk*6
cranberry Juice*6
jui [a Chinese medicinal herbal tea]*7
L-tryptophan*8
lupinus termis bean (cultivated in Egypt, a food protein supplement that contains quinolizidine alkaloids)6
niacin (liver damage due to long exposure) 9
tahini (pulped sesame seeds)*6
Food and Supplements that Interfere with Platelet Function
This list contains food and supplements that can change the way platelets work and make it more difficult for your blood to clot. They do not reduce the platelet count unless noted. A small quantity of these substances will probably be safe and not cause a problem.
There are many drugs such as Plavix and Coumadin that are designed to interfere with platelet function as well as other drugs such as aspirin that reduce platelet function as a side effect of their other uses. The food and supplements listed can amplify the effect of these medications. See the results of the NIH Conference on Dietary Supplements, Coagulation, and Antithrombotic Therapies held January 13-14, 2005, for more information and an extensive bibliography.
Many of the listed substances are also antioxidants or have other properties that promote healing. A balance is important. We are publishing this list so you are aware that everyday or easily-available substances can have an effect on platelets, although their anti-clotting action is much weaker than pharmaceuticals.
If you have a reasonably high platelet count and few bleeding symptoms, many items on this list will not cause problems unless you ingest large quantities. Ironically, some patients with ITP have a clotting problem and are taking blood thinners. Others may have a clotting problem and not know it. The propensity to clot and medication status are important factors when considering diet choices. Please discuss any concerns with your doctor.
aspartame (NutraSweet, can also reduce the number of platelets)16
beer (including non-alcoholic beer)17,18
blueberries19
chocolate (dark)20
coffee21
feverfew22
garlic23
onions24
gingko biloba25
ginger26
ginseng27
green tea28
guarana (a dietary supplement)29
kiwi fruit30
omega 3 fatty acids (hemp seed, fish oil)31, 32
pycnogenol (pine bark extract)33
quercetin, rutin, and related bioflavonoids34, 35
red/purple grape products (grape juice, red wine, raisins, grape seeds)36
red wine37
tomatoes38
vitamin E39
wood ear or cloud ear mushroom (Auricularia auricula-judae, used in Chinese cuisine)40