Concerns about plastic safety have been growing over the years, and the media has stepped up its efforts to expose potential dangers associated with plastic compounds such as bisphenol A (BPA) and phthalates. The problem is – there is very little scientific evidence linking plastic to human harm, and no credible evidence that our current typical exposures to BPA poses any health risks at all (so say the health agencies of the United States, Canada, the European Union, and Japan). But that’s not a very exciting story, is it?
Instead, what we often hear in the news is that microwaving our plastic containers or drinking from plastic water bottles could be dangerous to our health… and that BPA-free containers are better for baby. But where did the media come up with these ideas? I asked Dr. Chuck McKay, a toxicologist and emergency medicine physician at the University of Connecticut, to explain how safe levels of exposure (to various chemicals) are determined, and how to know if news reports are based on scientific evidence. I hope you’ll listen in to this educational Webinar.
Some of my favorite take-home messages from the Webinar include what I call “just becauses”:
1. Just because you can find a substance in your urine doesn’t mean it’s harmful. (Asparagus anyone?)
2. Just because an animal reacts to a substance, doesn’t mean that humans will. (How often have you caught a cold from your dog?)
3. Just because extreme doses of a substance can cause harm, doesn’t mean that tiny doses also cause harm. (Consider radiation exposure from riding in an airplane versus being near ground zero of a nuclear strike).
4. Just because something has a theoretical potential to harm, doesn’t mean it will. (Will you really be attacked by a shark in 2 feet of water at your local beach?)
5. Just because someone conducted a research study doesn’t mean their findings are accurate. (Do you really believe the Cosmo polls? There’s a lot of junk science out there!)
For an excellent review article of the high-quality science behind plastic safety, please check out this link. In the end, there are far more important health concerns to worry about than potential exposure to plastic compounds. And throwing out all your plastic containers may not even reduce your exposure to BPA anyway… A recent study found that people had higher concentrations of BPA in their urine when they followed a plastic-free, organic diet! Their exposure was actually traced to ground cinnamon, coriander, and cayenne pepper. Who knew?
Eye diseases and vision loss are becoming more common in the United States as diabetes rates rise and the population ages. Many eye conditions worsen very slowly and have no noticeable symptoms in their early stages. For this reason, getting an annual eye exam is extremely important. But is there anything we can do to prevent eye disease from a nutritional perspective? Experts believe that there is such a thing as an “eye-healthy diet.” I interviewed Dr. Jeffrey Anshel, President of the Ocular Nutrition Society, and Dr. Elizabeth Johnson, a leading nutrition researcher, to get their views on the subject. Please listen to the full HealthyVision podcast here.
Some of the my favorite learning points from the show:
1. Which foods are healthy for the eyes? The human retina contains about 1000 times more concentrated carotenoids (found primarily in plant pigments) than any other part of the body. Our eyes use these pigments to protect themselves from the photo-damage of sunlight. Carotenoids (including beta-carotene, lycopene, lutein, and zeoxanthin) are found in highest concentrations in dark green, leafy and brightly colored vegetables. Egg yolks are also a good source of carotenoids. Interestingly, our retinas have a predilection for omega-3 fatty acids (found in fatty fish) to protect the eyes from UV radiation. My bottom line – the most eye-healthy meal on earth is probably a salmon salad Niçoise (see photo image above)!
2. Are carrots good for our eyes? While carrots can be part of healthy diet, choosing carrots as our primary source of vegetable intake may not be a good idea. Carrots contain beta-carotene, which competes with other carotenoids for transport molecules. Beta-carotene is a pretty good competitor and can “bump off” lutein and zeaxanthin from getting transported to the retina. Adults don’t process beta-carotene as well as kids do, so too many carrots may not be a great thing after all (especially as we get older)!
3. Should I take nutritional supplements for the eye? It’s always best to get your carotenoids from real food. However, some people (who take blood thinners for example) cannot eat dark green leafy vegetables because they also contain Vitamin K which can interfere with the medicines. For those who cannot get sufficient carotenoids from food, supplements may be beneficial.
4. What is the connection between obesity and chronic eye disease? While obesity is a risk factor for diabetes, and diabetes can cause chronic eye disease, there may be another problem at play. Carotenoids are fat soluble, and so they are preferentially stored in fat cells rather than remaining suspended in our blood stream. When we have larger fat stores, that fat may “mop up” the healthy vegetable carotenoids that we eat, without allowing them to be transported to the eyes to support retinal structures. Some researchers suggest that obese individuals may need to increase their carotenoid intake with supplements in order to prevent eye pigment deficiencies and potential macular degeneration. Losing body fat is also an important strategy of course.
Other questions answered in the podcast:
* How does cooking impact the nutritional value of fruits and veggies?
* Is there such a thing as over-supplementation (especially with Zinc)?
* How many veggies do I need to meet my daily carotenoid requirements?
* How do I know which vitamin supplements to trust?
I hope you enjoy the podcast – and redouble your efforts to eat a diet rich in fruits, veggies, fish and eggs and maintain a healthy weight. Remember that even though your mom may have told you that Bugs Bunny’s diet was best for your eye health, Popeye’s veggie of choice is even better for you!
This year’s finalists for the Boys & Girls Clubs’ Fit Family Challenge are about to be announced. I’ve had the privilege of acting as nutrition coach for the semi-finalist families, and have had fantastic interactions with them about common nutrition questions. In my continuing Q&A series, I thought I’d share some of our email conversations:
Q: How many calories do I need per day, and how many should I eat to lose weight?
I like to use this Mayo Clinic calculator to get a rough estimate of daily caloric needs. If you enter your height, weight, age, and activity level it will tell you approximately how many calories/day you need to maintain your weight. To lose one pound a week, you need to subtract 500 calories/day from that number. So, for example if the calculator suggests that you need 2000 calories/day – you should follow a 1500 calorie/day diet to lose 1 pound a week. Studies have shown that people who drop more than 500 calories below their daily maintenance needs have a hard time sticking to their diet. You may feel weak, trembly, and irritable if you cut down too low too fast. You will have to play with the amount a little bit since the calculator is not exact – if you don’t see the scale moving when you cut out 500/day, then you have to wonder if you’re counting calories correctly or perhaps if you have to go a little bit lower still. Unfortunately, the “reward” for losing weight is that you have to permanently eat less when you are at your desired goal because there is less of you to feed!
Q: What do you think about sports drinks? Do my kids need them when running races?
As far as sports drinks are concerned, their benefits are often over-hyped and exaggerated. That being said, I believe they do have a role in hydration during endurance sports like long distance running. When you do strenuous exercise for long periods of time (over 1 hour of effort) you lose a lot of body salt and minerals (electrolytes) in your sweat. It’s important to replace certain key electrolytes so your body doesn’t become depleted and begin to cramp. This is more likely to happen to folks running very long distances, such as marathons and triathlons. However, if it’s hot during your race, you could be at risk for dehydration and electrolyte loss as well.
Regular Gatorade (made by Pepsi Co.) has water, sugar, sodium, and potassium in it. Powerade (made by Coca Cola) has water, sugar, sodium, potassium and B vitamins. Powerade has a little bit higher sugar concentration, which could be an advantage on a long run. Both are reasonable choices for hydration during a race.
The rough rule of thumb is to take in 6-12 oz of fluid for every 20 minutes of running. Water is sufficient for runs that last less than an hour. Sports drinks (or adding electrolyte gels/chomps to water) are helpful if your run will last longer than an hour. It’s better to sip the water slowly at regular intervals than to dry to gulp it all down at one time. You may feel nauseated or have a “sloshy stomach” feeling if you don’t spread out your hydration.
Sports drinks can be quite expensive – and you can easily create your own at home. The World Health Organization has a simple recipe for rehydration fluids, and I found this (probably slightly tastier) version on a blog site.
Outside of endurance sports, I don’t see a physiologic need for sports drinks (with the exception of extreme sweating in hot weather or during illness with vomiting and diarrhea) – they can add unnecessary calories to your diet.
Q: Should I cut down the amount of salt in my diet?
Not necessarily. Too little salt, as well as too much salt, have both been shown to be unhealthy. If you’re eating a lot of fast food, you’re probably getting too much salt. If you cook for yourself and focus on fruits and veggies, whole grains, and lean protein you may not need to cut back. Unless you have a kidney problem or very high blood pressure, salt is generally not dangerous for you. About 2.5g of salt/day (roughly a teaspoon full) is optimal, but for most people up to 4g/day probably won’t hurt (and at least one study suggests that heart disease risk doesn’t increase until the daily intake of salt exceeds 7g/day).
I’ve continued to have terrific email questions and answers with the Boys & Girls Clubs’ Fit Family Challenge participants. I thought I’d publish some of our conversations so that you can participate as well. The Lang family shared this image of their son eating dinner next to the latest USDA dietary recommendations “MyPlate” materials. A picture’s worth 1000 words, isn’t it?
This cute fella is a healthy weight, he is very athletic, and he’s also wondering where chicken nuggets, french fries, and pizza fit in to the MyPlate dinner plans… His mom asked me how to make more “kid friendly” healthy meals. Perhaps some folks reading this have some success stories that they’d like to share? Here’s what I had to say to the Langs and others…
1. My son doesn’t think the MyPlate suggested meals are kid friendly. What can we do?
I wonder if your son would be open to trying healthier variations of the foods he likes? You could make a pretty tasty pizza with whole wheat crust, grilled veggies, a little pesto or tomato sauce and some ham cubes (ham is much lower in fat than sausage or pepperoni) and low fat shredded mozzarella. You can get a pizza stone to help crisp the crust in a regular oven. The pizza would probably reheat well so you could make it in advance too.You can bread chicken strips and bake them (instead of frying them) to simulate healthy chicken “nuggets.” Same for fish sticks. You can try sweet potato fries for a healthier fry option – bake them in the oven with a little olive oil, salt and pepper. More nutritious, kid-friendly recipes may be found at KidsHealth.org
2. Do my kids need 8 cups of water a day?
As far as water is concerned, the amount you need really depends on how much liquid you’re getting from other sources (food, beverages) as well as how much you’re sweating (exercise), how hot/dry the environment is and how much you weigh. Eight cups/day is a very rough rule of thumb. Some people need more or less depending on the day. Unless you are doing extreme exercise (in the heat) that requires fluid replacement before you notice that you’re thirsty, thirst is a good indicator of whether or not you need to drink. Also, I’ll tell you a doctor secret – all you need to know about hydration is in your urine color. Urine becomes very concentrated (dark yellow) when you are dehydrated. If you drink enough water to keep your urine a nice light yellow, then that’s all you need.
3. What are the best vegan protein substitutes for meat?
Concentrated vegetable protein is primarily derived from soy (tofu and tempeh) and wheat (seitan). Nuts and seeds also contain some degree of protein, as well as beans, lentils, and rice. Tofu, tempeh, and seitan can be molded into burger and hotdog shapes and may be prepared to mimic meat flavors. Keep in mind that concentrated soy or wheat proteins may not agree with your intestinal tract (some complain of excessive gas and bloating). So if you have those reactions, at least you’ll know that it’s quite common.
4. Is it healthy to be a vegetarian? Is there such a thing as too much fruit and veggies?
Vegetarianism can be healthy, though it takes some effort to ensure that adequate amounts of nutrients are received – especially if you’re vegan (no dairy, no eggs). The most common deficiencies for vegans are iron, B12, calcium, Omega-3 fatty acids, protein, and Vitamin D. (You can read more about how vegetarians can overcome these deficiencies here.) I guess my main concern with veganism is the low omega-3s. It is basically impossible to get enough omega-3 fatty acids from plant sources (certain seeds, you may have heard, have a good amount of omega-3 fatty acids but what they won’t tell you is that plant omega-3’s aren’t processed by the body so they remain inactive and don’t provide much benefit.) Omega 3 fatty acids form a protective layer on the outside of cell membranes by reducing inflammation. This is particularly helpful in the reduction of plaque build up in heart arteries, and reducing the risk of various dementias (such as Alzheimer’s) that have an inflammatory cause.
Excellent sources of omega 3 fatty acids are oily fish (sardines, salmon, mackerel, sea bass). This is why the American Heart Association (and MyPlate.gov) recommend 2 servings of oily fish/week for optimal health. Vegetarians are missing out on this important benefit.
As far as eating too many fruits/veggies is concerned – I can’t think of too many potential harms from eating large amounts of fruits/veggies (other than weight gain if you really eat a lot of fruit – they have quite a bit of natural sugar). The real harm comes from excluding vital nutrients by eating plants exclusively (without a careful strategy to get the right plant sources of vitamins and minerals, along with omega-3 supplements).
This year’s Fit Family Challenge competitors are smart, savvy, and full of great nutrition-related questions! I just finished a one hour conference call with 10 family finalists from across the U.S. and Hawaii. As part of their challenge to adopt healthy diet and exercise practices, they were asked to send me their most burning nutrition questions. One mom told me that her goal was “to teach her girls how to think critically” about health information. I was so pleased to see those values being promoted that I thought I’d share some of our mythbusting FAQs here on the blog:
1. I live in a community that doesn’t add fluoride to the public water supply. Do my kids need to take fluoride supplements?
Fluoridation of our water supply is considered to be one of the top 10 most effective public health initiatives of the 20th century. Enhancing the natural fluoride content of water results in up to a 60% reduction in tooth decay for kids! The cost to a community of adding fluoride to the water supply is about 50 cents per person per year, so it’s really quite affordable. I’m not sure why your community water hasn’t been fluoridated, but it’s estimated that about 1/3 of Americans still live in communities that haven’t supplemented their water with fluoride (so you’re not alone).
Our teeth use fluoride to strengthen our enamel – and we can get fluoride to our teeth in two ways: 1) from our blood stream (e.g from the water we drink, digest, and absorb) and 2) topically (e.g. from toothpaste). Studies have shown that it’s best to get fluoride via both routes for optimal enamel strength. For children living in areas where the water is not fluoridated, the American Dental Association (ADA) recommends fluoride vitamins until at least age 16. There are two strengths of fluoride vitamins, and the dosage required depends on the fluoride levels in the local water supply (you can ask your local Water Department for that information if you haven’t already). Keep in mind that most children’s permanent teeth (with the exception of “wisdom teeth”) erupt by age 13 – and before that age there is no way to get fluoride to them except via the blood stream. So digesting fluoride (via water or vitamins) is critical to strengthen those teeth that haven’t broken through the gums yet.
2. Should parents be concerned about hormone levels in milk? Is there an advantage to buying organic milk?
All mammals release trace amounts of hormones into their milk. Cow’s milk naturally contains a small amount of bovine somatotropin (bST) which is a protein that is quickly broken down by our stomachs when we drink milk. Some farmers give their cows additional amounts of the hormone to stimulate milk production. This rbST (or BGH) is virtually identical to naturally occurring cow hormones and the decades of research we’ve collected has been reviewed by the FDA (Food and Drug Association), WHO (World Health Organization), NIH (National Institutes of Health), AMA (American Medical Association), and ADA (American Dietetic Organization) – and all agree that rbST is safe for human consumption in the levels it occurs in cow’s milk. Interestingly, studies have shown that milk hormone levels in organic milk is essentially identical to levels in regular milk. There is therefore no advantage in buying organic milk insofar as hormones are concerned.
I believe that cow’s milk is safe and nutritious for kids (so long as they have no milk allergies or lactose intolerances). The milk/hormone scare is kind of an urban legend, so I wouldn’t be too worried about it. Your girls haven’t suffered any harm from drinking regular milk – and it’s great that you all enjoy the skim variety, by the way. Lower calorie options can help you maintain your weight over your lifetime.
3. Are there lifestyle choices that I can make to reduce my risk of getting cancer? Can vitamins help?
You are right that there are lifestyle choices that can substantially reduce your risk (and your childrens’ risk) of getting cancer. However, there is no way to guarantee that you’ll never get cancer, no matter how carefully you control your diet and lifestyle. Nevertheless it’s an excellent idea to do what we can to reduce our risks. Cancer is actually a complicated collection of different diseases, and so specific behavior changes may reduce the risk of certain cancers but not others. For example, a high fiber diet may reduce the risk of colon cancer, but not skin cancer.
Also note that it’s very hard to prove that any one dietary change (such as consuming a larger amount of one particular vitamin or herb) has a direct impact on cancer risk. What works is sometimes more general (such as avoiding becoming obese). Here are some behavior changes that have been scientifically proven to reduce cancer risks or prevent certain cancers:
1. Smoking cessation
2. Regular use of sunscreen
3. A diet rich in fiber (i.e.lots of fruits and veggies and whole grains)
4. Maintaining a healthy weight
5. Regular exercise
6. HPV vaccines (especially for young girls – can prevent cervical cancer) and hepatitis vaccines (can prevent liver cancer)
7. Drinking very little alcohol (no more than 1 drink/day)
Screening for cancer is also important – because catching a cancer early is often the best way to cure it. The most effective screening tests are:
1. Colonoscopies (for adults over age 50)
2. PAP smears (for sexually active women and women who haven’t had hysterectomies)
3. Physical exams to check for skin cancer, oral cancer, and testicular cancers
Mammograms and prostate blood tests are less effective at catching cancers early, but they are recommended by most medical professional associations.
Multivitamins are not recommended for cancer prevention. Although it would seem that vitamins could help reduce the risk of cancer, large studies have shown that they do not reduce the risk of cancer, and may even increase one’s risk (especially vitamin E.) The best source of vitamins is healthy food – and their fiber benefits are excellent as well. For a nice summary of the unhelpfulness of vitamin supplements, please see this ABC News summary of recent research.
Latest Tweets from @DrVal
Could not authenticate you.
Better Health Audio
Featured Audio
Healthy VisionTM with Dr. Val: Safe Contact Lens Wear and Care
It’s no secret that doctors are disappointed with the way that the U.S. healthcare system is evolving. Most feel helpless about improving their work conditions or solving technical problems in patient care. Fortunately one young medical student was undeterred by the mountain of disappointment carried by his senior clinician mentors…
I am proud to be a part of the American Resident Project an initiative that promotes the writing of medical students residents and new physicians as they explore ideas for transforming American health care delivery. I recently had the opportunity to interview three of the writing fellows about how to…
I m often asked to do book reviews on my blog and I rarely agree to them. This is because it takes me a long time to read a book and then if I don t enjoy it I figure the author would rather me remain silent than publish my…
When I was in medical school I read Samuel Shem s House Of God as a right of passage. At the time I found it to be a cynical yet eerily accurate portrayal of the underbelly of academic medicine. I gained comfort from its gallows humor and it made me…
I am hesitant to review diet books because they are so often a tangled mess of fact and fiction. Teasing out their truth from falsehood is about as exhausting as delousing a long-haired elementary school student. However after being approached by the authors’ PR agency with the promise of a…
Concerns about plastic safety have been growing over the years, and the media has stepped up its efforts to expose potential dangers associated with plastic compounds such as bisphenol A (BPA) and phthalates. The problem is – there is very little scientific evidence linking plastic to human harm, and no credible evidence that our current typical exposures to BPA poses any health risks at all (so say the health agencies of the United States, Canada, the European Union, and Japan). But that’s not a very exciting story, is it?
Eye diseases and vision loss are becoming 
I hope you enjoy the podcast – and redouble your efforts to eat a diet rich in fruits, veggies, fish and eggs and maintain a healthy weight. Remember that even though your mom may have told you that Bugs Bunny’s diet was best for your eye health, Popeye’s veggie of choice is even better for you!
This year’s finalists for the Boys & Girls Clubs’ 
I’ve continued to have
This year’s
