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Caffeine and Pregnancy: How Much Risk?

Several studies suggest a link between caffeine consumption and risk of miscarriage. But the cause and effect has never been clear: does caffeine increase a woman's risk of miscarrying, or do women who are already at low risk for miscarriage tend not to drink caffeine? (To wit: morning sickness, which is a sign of a healthy pregnancy, hardly makes you crave a cup of Joe.) At Kaiser Permanente Northern California's Division of Research, reproductive and perinatal epidemiologist Dr. De-Kun Li wanted to parse the association. He and colleagues recruited 1,063 women in early pregnancy, quizzed them about their caffeine intake and followed them to the end of their pregnancies. The researchers also checked to see, crucially, whether women had altered their caffeine-drinking habits after becoming pregnant — that way, scientists were able to control for the effect of morning sickness. TIME asks Li's expert opinion. (Click to hear the podcast.)

Q: How much caffeine is safe to drink during pregnancy?

A: What we found is that for women whose caffeine intake was more than 200 mg every day, the risk of miscarriage was double compared with women who did not have any caffeine during pregnancy. For those who consumed more than 200 mg a day, their miscarriage rate was about 25%. Below 200 mg, we also saw a slight increase in risk, [but] we were not able to make a more definitive assessment. Generally speaking, though, for [risks due to] environmental exposure in the context of miscarriage, there is rarely a threshold effect. Usually, the higher the dose, the bigger the effect.

I would think, given this study finding and other study findings before, the first choice for women should probably be to stop drinking caffeine entirely — at least for the first three to four months of pregnancy. But if you really have to drink, I think you should limit yourself to one regular coffee a day or less. Two hundred mg of caffeine is roughly about one-and-a-half to two [8 oz] cups of regular coffee. [In our study], most of the caffeine came from regular coffee. [It's also found in tea, hot chocolate and soda.] [If you drink] regular soda, 200 mg is roughly equivalent to five 12 oz cans.

There are two mechanisms that have been hypothesized up to this point, linking caffeine to miscarriage. First, we know that caffeine can directly, easily cross the placental barrier. While adults can usually metabolize caffeine, a fetus usually can't, particularly in the early stages of development. So caffeine has a direct effect on cells, membranes and tissues. Those kinds of things for adults are OK. That's why we actually drink caffeine — because it interacts with our cell receptors. But for a fetus, particularly at the early stages of development, it may interfere with development.

Second, it's been known for a long time that high doses of caffeine can have a vaso-constrictive effect [in adults], which means it can make blood vessels contract. If the effect is severe in the mother, hypothetically it can reduce blood flow to the placenta and to the fetus. It's totally possible that [caffeine could have an impact in later pregnancy as well]. There could be other [associated] outcomes, like low birth weight, preterm delivery, even birth defects, or [problems with] neurological development. Those are all biologically plausible effects. It's just that we haven't demonstrated them. They're harder to study.

The message here is probably the less, the better. I would think if you wanted to be safe, you should probably cut down or even stop caffeine-drinking throughout pregnancy.

In Search of a Test-Tube Hamburger

On Monday, the clamorous animal rights group PETA announced it would award $1 million to the first person to come up with a way to make commercially viable in vitro meat by 2012. The fake meat would have to be indistinguishable from the real deal, according to competition rules, and it would have to be cheap enough to succeed in the marketplace.

In theory, this seems like an excellent idea, with the potential to ease the burden on the environment from meat production, reduce greenhouse gas emissions and improve human health. In practice, however, the chances of anyone actually winning the prize seem slim. "No one has yet produced [in vitro meat]. No one has succeeded in coming close," says Dr. Stig Omholt, director of Norway's Centre for Integrative Genetics and chair of the In Vitro Meat Consortium, which held its first symposium this month. Still, Omholt says, "it seems possible to develop this technology."

Scientists first began working with in vitro proteins, grown from animal cells in Petri dishes and bioreactors, about a decade ago. The technology was originally conceived as a means to make food for astronauts to take on long space missions; in 2000, the first edible in vitro muscle protein was created from a goldfish by the NSR/Touro Applied BioScience Research Consortium. Soon after, scientists realized the broader applicability of the technology and began developing it to feed the rest of us earthbound folk.

Here's how the process works: scientists biopsy stem or satellite muscle cells from a livestock animal, such as a chicken, cow or pig. The cells are then placed in a nutrient-rich medium where they divide and multiply, and are then attached to a scaffolding structure and put in a bioreactor to grow. In order to achieve the texture of natural muscle, the cells must be physically stretched and flexed, or exercised, regularly. After several weeks, voila, you have a thin layer of muscle tissue that can be harvested and processed into ground beef, chicken or pork, depending on the origin of the cells. But don't expect to see big, juicy in vitro steaks anytime soon; the technology has not yet been able to synthesize blood vessels or grow large, three-dimensional pieces of meat.

Though it sounds a lot like Frankenfood, scientists note that in vitro tissue engineering is not the same as genetic engineering, a common misconception. "We use natural cells from natural animals," says Dr. Vladimir Mironov, a tissue engineer and assistant professor at the Medical University of South Carolina. "We don't change Mother Nature, we just try to imitate it." But there's always room for improvement — scientists can design meat, for example, that is high in healthy fats, such as omega 3s and 6s. Creating the meat in a lab also decreases its exposure to bacteria and disease, which have riddled the livestock industry, injuring consumers and causing extensive meat recalls.

The technology to produce in vitro meat is almost in place, says Mironov, but "there are bottlenecks" in the process — namely scale and cost. Given the current technology, it would cost $1 million to turn out a 250g piece of beef. The problem boils down to producing a cell-culture medium in large enough quantities at a low enough price (it's the same problem facing tissue engineers who are attempting to grow artificial organs for human transplant). So, two weeks ago, an international group of experts assembled in Norway for the first In Vitro Meat Consortium symposium to talk about how to scale up the technology and sustain it long-term. The group concluded that it will be possible to produce in vitro meat in large quantities in the future, but not without funding to continue research. Scientists estimate that in vitro chicken could be produced for about double the current cost of regular livestock chicken, a price that would fall as the process becomes more efficient. "The consensus was that this is doable," says Omholt.

Doable, yes, but not by 2012. It will take at least five to 10 years of research, followed by an extensive approval process, to ensure that any in vitro meat produced is fit for human consumption. Though PETA's competition may not produce a winner soon, the hope among scientists is that it will create interest and funding. As for selling fake meat to the public, that's another matter. But then, in an era of artificial hearts and over-the-counter genetic tests, perhaps even meat from a test tube has a future.

links for 2008-04-24

• It's no LOL: Few US doctors answer e-mails from patients - Yahoo! NewsSuzanne Kreuziger is a registered nurse who uses e-mail almost exclusively to communicate with friends. But when it comes to reaching her doctor, there's a frustrating firewall.

Scalp, Neck Skin Cancers Most Lethal

Not all melanomas are created equal. That's the conclusion of a study by University of North Carolina researchers who found that skin cancers can vary in lethality depending on where they start.

After analyzing an exhaustive dataset of over 50,000 cases of melanoma in the US that were diagnosed between 1992 and 2003, the scientists, led by Dr. Nancy Thomas, a dermatologist, discovered to their surprise that patients with lesions in the scalp and neck died almost twice as fast after diagnosis as those whose tumors started anywhere else on the body. "The results really did surprise us," says Thomas. "For a long time, there has been a lot of controversy over whether all head and neck melanomas had worse survival, and this study shows a large difference in survival for scalp and neck tumors." Interestingly, cancers of the face and ear, other common locations for melanoma, were not linked to reduced survival. In fact, cancers starting in these areas actually had better prognosis than those beginning in the trunk or extremities, which usually have the best survival rates.

Thomas' study was not designed to tease out why these scalp and neck lesions are particularly dangerous, but she notes that those areas are crisscrossed with extensive lymph and blood vessels — such networks can make it easier for cancer cells to both grow and spread. Dr. Vijay Trisal, a cancer specialist at City of Hope National Medical Center in Los Angeles, also notes that these areas receive the most sun exposure. "The maximum sun exposure areas are to the scalp, face and neck," he says, "so it makes sense biologically that cancers here would be different from those in areas that rarely see sunlight."

Thomas also acknowledges that at least part of the reason for the worse survival could be related to the fact that scalp lesions are harder to detect, and less likely to be screened, given that in most cases, the region is covered with hair. But even this can't explain the entire trend. "There is something independent of the screening that is going on that we don't really understand at this point," Thomas says.

But even without such an explanation, the findings highlight the importance of proper screening. As part of any skin exam, say Thomas and Trisal, the scalp should be no different than any other part of the body; in fact, as this study shows, they should probably be the first place doctors and patients look.

links for 2008-04-22

• Ten typographic mistakes everyone makes | Life, Tutorials | Receding HairlineThe personal and professional website of Christopher Phin
• Here Comes Everybody: The Power of Organizing Without Organizations (Event Video/Audio) | Berkman Center
• Translation of Research Into Practice: Why We Can't "Just Do It" -- Green and Seifert 18 (6): 541 -- The Journal of the American Board of Family Medicine