Michael Greger MD

Michael Greger MD

Posted October 30, 2011

Published in Health

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Ask the Doctor: Q&A with Michael Greger, M.D. (Week 7)

Read More: apple cider vinegar, Aricept, BPA, cancer, erectile dysfunction, greens, infertility, obesity, pine needles, plastic, PMS, potassium, saffron, scurvy, tea, toxins, vitamin C

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This is another sampling of the more than 600 comments and questions I've responded to on Please feel free to leave any follow-up questions here or on any of the hundreds of videos on the more than a thousand topics covered on And remember, there's a new video posted every weekday, so to make sure you don't miss any:

May you and your family have a happy, exciting Halloween!

LynnCS asked on The Healthiest Vegetables: I noticed that Pine Needles in a tea is a good antioxidant. I am wondering if needles from a Douglas Fir or redwood would have the same properties. I am Raw Vegan and always interested in the options.

Pine needles have so much vitamin C that pine needle tea has been used with great success historically as a cure for scurvy. On the other hand, there have been toxins found in the needles of some pines, so I would recommend sticking to more conventional dark green leafy leaves. If you want to be more adventurous, though, then the best resource I'm aware of is From Crabgrass Muffins to Pine Needle Tea by Linda Runyon.

HereHere asked on Which plastics are harmful?: I wish you had links to the studies. My dad thinks the whole BPA issue is a hoax (and human-caused climate change, too, if you can believe it). But, he claims to be a scientist, so putting a few good studies in his hands would help. Oh, he also doesn't think there is an obesity epidemic in America.

Not sure if there's any talking sense to a climate skeptic, but there are more than 1,000 free scientific articles on bisphenol A accessible through PubMed Central (PMC). Unlike straight PubMed, PMC indexes only articles that are free and open to the public (2 million to date!).

Probably the most interesting study published this year on the topic was "Most plastic products release estrogenic chemicals: a potential health problem that can be solved," which found endocrine disrupting chemicals even in "BPA-free" plastics, based on the in-vitro effects on estrogen receptor-positive human breast cancer cells. In some cases, BPA-free products released even more chemicals having estrogenic effects than BPA-containing plastic products. The good news is that a new study found that one could dramatically reduce one's exposure to these chemicals (both BPA and "penis-shrinking" pthalates) by choosing more fresh, unpackaged foods.

Victor Van Epps asked on Nation's diet in crisis: If you would recommend one journal for a busy biology student to read to keep up with the latest nutrition research, what would it be?

My favorite journal is probably the American Journal of Clinical Nutrition, but I strive to at least skim through every issue of most every English-language nutrition journal in the world (see my list here). The few you'll note missing from my list are mostly industry journals (like New Horizons In Nutrition And Health, published by the Butter Council), which are great for comic relief but don't make my must-read list.

aeason asked on Is vinegar good for you?: I have heard that apple cider vinegar which I know contains potassium, that is can also leach potassium, and can thus contribute to high blood pressure. Do you have any information about this?

There are a baker's dozen articles in the medical literature on apple cider vinegar (as indexed by the National Library of Medicine), and indeed there is a case report "Hypokalemia, Hyperreninemia and Osteoporosis in a Patient Ingesting Large Amounts of Cider Vinegar" that does suggest ingestion may lead to potassium wasting. Acetic acid in vinegar is rapidly metabolized in the liver into bicarbonate, and potassium is used by the kidneys to excrete bicarbonate from the body. So chronic use of high doses could lead to problems-the woman described in the report was drinking more than a cup of vinegar day! One would not expect any such problems as the doses described in the studies featured in the Is Vinegar Good For You? video (2 teaspoons with meals). I would, however, warn against apple cider vinegar pills. A study published in the Journal of the ADA of 8 such products found some "could be considered poisonous, as indicated by the Consumer Product Safety Commission...."

eileenmcv asked on Saffron versus Aricept: 30 mg transposes into about how many stigmas per day?

Each flower yields 7mg dried saffron, and I think there are 3 stigmas per flower, so 30 mg should be about 13 stigmas. There's research on saffron and infertility, cancer,PMS, obesity, and erectile dysfunction. I'll be rolling out more videos evaluating the latest science on spices-stay tuned!

- Michael Greger, M.D.