Thursday, June 28, 2012

Beneficial Bacteria in your Body

Microbiologists are excited about recent studies showing that the bacteria in our guts, throat, genital organs and on our skin can have newly discovered beneficial roles in health. We have some 500 different strains of bacteria in our intestinal tract; the average healthy adult carries about 5 pounds of them. From the mouth to the colon, they help us break down and digest our food and allow for its absorption. They also synthesize a range of vitamins, from the B group to vitamin K.

About 70% of our immune system resides in the lining of the gut; signals from good bacteria influence immune cell development and susceptibility to infections and inflammatory diseases. Researchers at the University of Pennsylvania have shown that when mice are treated with antibiotics to reduce numbers of beneficial bacteria, they have an impaired antiviral immune response and delayed clearance of systemic viruses or influenza in the airways. The researchers concluded that signals from beneficial bacteria stimulate immune cells in a way that is optimal for antiviral immunity.. This may be a way that good gut bacteria reduce your susceptibility to colds and flu.

The same researchers also looked at allergic lung inflammation, similar to asthma in humans, and found that mice given antibiotics had higher levels of basophils in their white blood cells, and elevated seum IgE – seen in allergic disease. Researchers at the University of British Columbia found that mice treated with the antibiotic vancomycin reduced the diversity of microbes in the gut and increased the susceptibility of the animals to experimentally induced asthma. They conclude that normal bacterial populations can positively influence the response to allergens in the environment, making inflammation and asthma less likely. The bacterial multitudes in our bodies may have functions never before appreciated.

Antibiotics are life-saving drugs in many situations, including streptococcal throat infections (that can lead to heart valve damage), bacterial meningitis, bacterial pneumonia, urinary tract infections, et al. The purport of this column is not to criticize their use when needed, but to underline the importance of beneficial bacteria in the gut.

Research on the ‘microbiome’ is a hot topic currently, with exciting implications for human health. Microbiome is defined as the totality of microbes in the body (bacteria, viruses and fungi), their genetic elements and environmental interactions. What you can do right now to keep your microbiome in good shape is to feed your helpful intestinal bacteria the right food. Sugary foods that are low in fiber allow the ‘bad’ microbes to thrive. Avoid them. Certain foods are known as ‘prebiotics’ can help our beneficial bacteria. Examples are whole grains, oats, bananas, garlic & onions, artichokes and asparagus. In addition, many people take a ‘probiotic’ supplement that contains beneficial bacteria, and also eat fermented foods such as yogurt, kefir, and sauerkraut. Make sure the yogurt you buy contains living cultures, and avoid ones that are sweetened – it’s better to add fruit yourself. You can buy probiotic capsules at many grocery stores. Look in the refrigerated section and keep the capsules refrigerated at home to preserve the life of the bacteria therein.

If you take antibiotics for a bacterial infection, it’s a good idea to take a probiotic to restore your beneficial bacteria. This may help to prevent serious diarrhea after antibiotic use, which can occur when bad bacteria such as Clostridium difficile take over. Wait at least 2 hours after taking the antibiotic, so it can be absorbed into your bloodstream, before taking the probiotic. If you have asthma, a probiotic supplement might help – talk to you doctor about this.

Sadja Greenwood, MD, MPH - back issues on this blog. Write me a comment, and I'll answer you.

Friday, June 22, 2012

GMO labeling, the Farm Bill, & anti-cancer herbs and spices

In November we will be voting on a referendum in California requiring that all genetically engineered foods be labeled. If it passes, California will be the first state to require such labeling on packaging. Citizens in Europe, Japan and other countries (almost 50 in all) have access to such knowledge. This is an historic occasion for voters – you should know that companies such as Dow and Monsanto will put up a strong campaign against the referendum, and may sue the state if it passes, as they threatened to do in Vermont, where a legislative bill for labeling did not make it out of committee.

The referendum is important because ‘superweeds’ have developed in response to the herbicide ‘Roundup’ (glyphosate). The result has been heavier spraying of the Roundup Ready corn and soybeans that have been genetically modified to withstand such spraying. About 90% of soybeans and 70% of corn and cotton grown in the US are Roundup Ready crops. Additionally, Dow Chemical has asked for USDA approval of a type of corn that can withstand spraying by 2,4D (a defoliant similar to 2,4T used in Agent Orange in Vietnam war days). Many large-scale farmers in the Midwest approve of Dow’s new crops, saying that resistant weeds have become a crisis and without new chemical approaches, farmers would have to plow more and thereby increase soil erosion. On the other hand, Sweden, Norway and Denmark have banned the use of 2,4D, because of toxicity to workers (central nervous system symptoms, dermatitis, possible long term effects on the children of women exposed in pregnancy, and possible increase in lymphomas). Farmers who do not use GMO crops fear genetic drift from the altered plants’ pollen, and also drift of the herbicides used.

This is clearly a complicated question, and we will hear a great deal about it in the run-up to the November election. Here is another reason to exercise your right to vote!

Th US Senate is currently considering the 2012 Farm Bill. Senator Kirsten Gillibrand (D- NY) is opposing a $4.5 billion cut from food stamps, which will then be opposed in the House of Representatives where a majority of Republicans have said they want deep cuts in food stamps. In addition, she wants to help markets that sell fresh produce in areas where it is not available, and encourage the creation of insurance for specialty crops such as apples and onions. To take action on Gillibrand’s amendment that would restore cuts from nutrition programs and redirect $500 million to healthy food programs, you can call Lynn Woolsey (415-507-9554), Senator Boxer (415-403-0100) and Senator Feinstein (415-393-0707). Senators Bernie Sanders (D-Vermont) and Barbara Boxer ( D-California) have introduced an amendment requiring GMO foods to be labeled nationwide. Call Senator Boxer about this as well, if you agree with such labeling.

I have just returned from a nutrition conference put on by the Center for Mind-Body Medicine. One of the speakers on cancer was Jeanne Wallace, who also spoke here at Commonweal last year with chef Rebecca Katz. Wallace listed the top 10 foods to block angiogenesis – the growth of new blood vessels that encourage cancer growth. They are:
*Spices – especially curry, ginger, garlic, parsley
*Berries – all types
*Green tea
*Parsley, peppermint, thyme
*Curry - turmeric, coriander, cumin
*Brazil nuts – for the selenium
*Cold-water fish/ Grass fed meat - for the omega-3 fatty acids
*Traditional soy foods - edamame, tempeh, tofu, plain soy milk
*Peanuts (boiled), red grapes/wine - resveratrol

I will write more about this conference in future columns. In the meantime, if you eat, be a food activist!
Sadja Greenwood, MD, MPH

Monday, June 4, 2012

Update on calcium

Recent reports of an increased risk of heart attack in people taking calcium supplements have been very confusing. For years we have been told to take calcium pills to supplement dietary sources of this mineral. Here’s the evidence so far. Calcium is critical for building and maintaining strong bones and teeth; it also plays a role in muscle contraction, nerve transmission, blood clotting and blood vessel flexibility.

A recent study in the Archives of Internal Medicine looked at 39,000 older women in the Iowa Women’s Health Study, and found a small decreased risk of death among women taking calcium supplements. This contrasts with two studies from the University of Auckland (British Medical Journal, 2010 and 2011) which looked at the U.S. Women’s Health Initiative and found that calcium supplements, with and without vitamin D, modestly increased the risk of a heart attack. The data are difficult to interpret, and more studies and further analysis is needed. A Canadian journal said “if 100 patients take calcium supplements, less than 1 will have a fracture prevented, and less than 1 will develop a heart attack
or stroke.” A small increased risk of kidney stones has also been shown in people taking supplemental calcium, but not with dietary calcium.

The Institute of Medicine concluded in 2010 that adults should get 1000 mg a day of calcium, and post-menopausal women should get 1200 mg. An adequate calcium intake is especially important in pregnancy and breast feeding. Girls ages 9 – 18 often do not get enough calcium in their diets due to a preference for sodas, fake foods and dieting. Supplements of calcium, magnesium and vitamin D as chewable tablets may be beneficial for them, as this is a critical time for bone building.

I conclude that it is vitally important to get enough calcium from our diets, and to use supplemental vitamin D if needed to raise levels of D to 30 ng/ml or higher. Good dietary sources of calcium include low fat milk products (think unsweetened yogurt and cottage cheese and nonfat or 1% milk), green vegetables (especially broccoli, collards, kale & bok choy), almonds, Brazil nuts, sunflower seeds, sesame seeds and dried beans. Calcium fortified soy milk and orange juice can help vegans get enough calcium. Some tofu is high in calcium; read labels to be sure. People with osteoporosis should talk to their doctor or nurse practitioner about the risks and benefits of supplemental calcium.

Studies of men have suggested that a high intake of calcium from dairy products may increase the risk of prostate cancer, but the evidence for this is inconsistent. Men can consider getting a maximum of dietary calcium from non-dairy sources of the mineral.

A 2006 study from the University of Pennsylvania showed that use of proton pump inhibitors (Nexium, Prilosec, Prevacid and others ) to reduce acid reflux is associated with an increased risk of hip fracture in people over 50, probably due to decreased calcium absorption and other mechanisms. Long-term use of these medicines increases the risk. Short term use is often indicated, but many people stay on these anti-reflux drugs for years. These medicines can also increase the risk of pneumonia, vitamin B12 deficiency and low magnesium levels. There are other ways of dealing with acid reflux, including weight loss, avoiding trigger foods and high fat meals, eating frequent small meals, and sleeping in a Lazy-Boy chair or with a wedge pillow if the problem comes on at night.

Here in West Marin are blessed to have local organic dairies that produce wonderful yogurt. Yea for farmers’ markets with their abundance of calcium rich vegetables

Sadja Greenwood, MD, MPH back issues on this blog