Are blood tests for food allergies a waste of time?

This is a question that came up last week when talking to a friend with some digestive issues surrounding specific foods. It's a bit of a complex topic, so I'll try to boil it down to the basics.

First of all, the term "food allergy" can manifest in different ways. It's like saying "vehicles". There are cars, which are common and generally well understood, but there's also helicopters, airplanes, and hovercrafts that we don't see everyday and most people don't have a clue how they work.

The first category of food allergies (lets call them the cars) are the classic ones that are mediated by histamine. They develop rather quickly and produce symptoms in the skin (hives, swelling), the gastrointestinal tract (nausea, vomiting, diarrhea, itchy mouth), and in the cardiopulmonary system (anaphylaxis). Peanut allergies are a common example. Respiratory allergies such as hay fever are mediated by the same mechanism.

The other category (helicopters and hovercrafts) is mediated by another class of antibodies called IgG. I like to think of these as personalized "kick-me" signs that your body makes for each foreign invader it has seen before. Of all the antibody classes, these are the most abundant in the body and their job is to activate the immune system to destroy the invader quicker than the first time you were exposed. So how are these related to food?

Although the human gastrointestinal tract was once thought of an impenetrable brick wall, the reality is that it can become damaged, and partially digested food comes in contact with the immune system. This can result in the body making the "kick me" signs against food proteins. Upon subsequent encounters, these food particle/"kick me sign" complexes clump together and circulate around and eventually deposit themselves somewhere, producing a myriad of symptoms that can seem totally unrelated to your GI system. These include skin rashes, fatigue, joint pains, and many others. This form of allergy is less well understood and the symptoms can be less predictable. It is also not yet an exact science.

As for the food allergy testing, the first type is done by most allergists by skin-prick testing. The second type (IgG) is done from the blood, usually ordered through specialty labs. The bottom line is that the tests have yet to be perfected and a lot hinges on the specific lab's methodology. No test is perfect, and this is certainly no exception. That said, they can provide a doctor with some useful information. For example, perhaps someone tends to show reactivity to oranges and grapefruits, suggesting that the whole citrus family may be problematic for them. In another case, someone may show reactivity to almost all foods on the panel. This would indicate that their digestive tract has become leaky (for lack of a better word) at some point, and they need to start by healing it. If nothing else, they provide a starting point for doing a clinical food elimination and re-challenge, which is after all the most certain way of identifying problematic foods. A recent review was published out of John's Hopkins University School of Medicine came to a similar conclusion - though diagnosing food reactions remains a challenge, IgG food allergy panels have shown promise for directing elimination diets, with clinically meaningful results.

Long as this post has become, it is far from comprehensive. If you suspect you have difficulty with some foods, I recommend seeing a medical professional with expertise in this area.

Regards,

Bryn

Is flax oil as good a source of omega 3's as fish oil?

The importance of Omega 3 fatty acids was first noted in inuit populations who ate a high fat marine diet, and yet had no cardiovascular disease. We've since learned that it was the nature of the fats that was responsible for the protective effects. It is now known that they are also important in brain development and our ability modulate inflammatory processes, which is the basic foundation of most diseases.

While it is true that flax oil does contain omega 3 fatty acids, they are not the same as those found in fish oils. The bottom line is the flax versions need to be converted in the body to the DHA and EPA, which are the beneficial omega 3's found in fish oil. Unfortunately this is an inefficient conversion at best, estimated to be between 5-20%. Flax is still a useful source, however it will not have the same therapeutic effects as the oils found in cold water fish. There are a few things to keep in mind when it comes to getting your fish oils.

1. Sources should come from small, cold water fish. The cold temperatures is what causes the fish to make omega 3's to prevent their cell membranes from freezing (think of butter in the fridge vs olive oil - butter is solid, olive oil is fluid). Also, the older and larger the fish, the more time it has been spending accumulating mercury and other toxic residues in it's fat tissue. Tuna is a well known example of a fish to limit/avoid because of it's mercury content. Good sources include sardines, herring, anchovies, cod, and salmon. Incorporating these into the diet is helpful, and in my opinion, the way we were meant to get them.

2. Supplements: You get what you pay for. When purchasing supplements, look at the label and see what fish they extracting the oils from. Also, look for EPA and DHA content. If all it says is "Fish oil" and/or it doesn't list the sources, it's best to move on. Although not required, some manufacturers test each batch for quality and heavy metal content, which is a huge advantage. With regards to supplements, one caveat - if you're pregnant, beware of cod liver oil. For most other people it's great, because it has vitamin A and D, which are both important. Vitamin A can be toxic to fetuses though, and should be avoided in pregnant mom and infants under the age of 1.

3. Omega 3 to Omega 6 ratio. A healthy balance between the two are optimal, and our culture tends to have an overwhelming abundance of 6 and a deficiency of 3. So, when considering supplementing, avoid ones that contain omega 6 and or 9 as well - they compete for the same enzymes as omega 3's, and just get in the way. Fatty acids are what make up our cell membranes. As you can imagine, there are a lot of them in our body! it takes time to shift the balance in favour of the omega 3's, but it's well worth it.

Warm regards,

Bryn

Today's task? Eat blueberries.

Blueberries are a personal favourite, and they happen to be in season. They have a lot going for them and if you want to start cultivating a healthy habitus, they provide an easy place to start. Without nerding-out (ok, maybe a little) on biochemistry, here's why:

Anthocyanin's are the blue-red pigments that give dark berries their colour. These pigments are at work to protect the fruit from oxidative damage from the sun, and to prevent them from breaking down. The result is that they're very high in antioxidants (one study estimates 20-50 times as powerful as vitamin C and E), which is what's responsible for many of the benefits listed below.

So here's what the blueberries will do for you:

1. Anti-aging, through it's antioxidant effects. It helps keep connective tissues strong and elastic.

2. Obesity, diabetes, and metabolic syndrome. A recent study compared rats fed high fat diets with or without blueberries for 3 months. The rats with the blueberries had less abdominal fat, lower cholesterol, lower triglycerides, and lower blood sugar and insulin levels than the ones eating the fat diet alone. The results were even better for rats on low fat diets and blueberries (no surprise there).

3. Preserve vision. The coloured pigments from fruits and veg help make up the part of our retina that is responsible for vision. Blueberries (and the like) have been shown to prevent age-related visual degeneration.

4. Brain function. Studies have shown that they can help improve memory and cognitive function. For you young ones out there, this (as many of these other benefits) is most effective if consumed regularly over the course of a lifetime rather than trying to play catch-up later in life.

5. Cancer prevention. Other compounds in the berries have cancer preventative and anti-cancer effects. I'll spare you the details.

6. Heart health. The combination of high fibre and antioxidants can help lower the bad cholesterol. They also enhance the quality of your blood vessels. It will make them stronger and more elastic through its' antioxidants; and can also help lower blood pressure.

7. Better elimination. And yes, I do mean dumps. 1 cup of blueberries contains about 15% of your daily intake of fibre. In addition to the number 2's, blueberries contain d-mannose, which is the same component responsible for the cranberry's effects on urinary tract infections. The d-mannose interferes with certain bacteria's ability to cling to the bladder and urinary tract wall. This helps prevent them from climbing up and infecting the bladder.

In conclusion, the kicker with blueberries (and why they're today's topic) is that they demonstrate an important concept - nutritional density. They have very high levels of nutrients, and yet are very low in calories. This is a concept we will likely revisit in the future.

Hope all is well,

B

For more information about this and other healthy foods, http://www.whfoods.com is a great resource.

Vitamin D and pregnancy

A curious mother-to-be in a recent prenatal class asked how much vitamin D she should be taking during her pregnancy. First of all, this was a great question as it calls into question the importance of Vitamin D for everybody, not just pregnant mothers. Our understanding of the "vitamin" has expanded greatly in recent years. Previously it was mainly implicated in calcium regulation and bone health, and the recommended daily amounts were set with that function in mind. It is now understood that contrary to it's name, vitamin D is actually a steroid hormone that has direct effects on our immune system, pancreas, cardiovascular system, brain, muscle, and cell cycle regulation (whose dysregulation is central in the development of cancer). The previous recommendations for adequate intake are not sufficient to positively affect these other systems. Thus, it's deficiency has been linked to development of many chronic diseases including multiple sclerosis and cancers (breast, colon, prostate, ovarian, lymphomas, among others).

As with most medically related questions, there's no blanket answer that applies to every person. Factors such as ethnicity, age, sun exposure, and season all affect a person's vitamin D status. Here are the important factors to consider when contemplating supplementing this important vitamin:

1. Get your vitamin D levels checked by a health professional (Naturopath, MD, Nurse practitioner) who is up to date on current standards and recommendations. This is the BEST way to determine how much you need, and for how long. Each persons circumstances are different and individualized care is ideal.

2. Season. Here in British Columbia, even if it were sunny 365 days/year and you spent the entire year stark naked at Wreck Beach, the UV index wouldn't be high enough to generate Vitamin D most of the year. June-August are great, but beyond these months it's just not strong enough. Throughout the late fall - early spring, it's most likely a good idea to supplement Vitamin D. In the summer time, 10-15 minutes of midday sun can provide you with about 3 days worth of vitamin D.

3. Skin tone. Melanin is the pigment in skin that makes it dark. In dark skinned individuals this reduces their ability to produce Vitamin D from sunlight.

4. The safe "Tolerable Upper Intake Level" established by the Food and Nutrition board of the National Research Council (in the USA) is 2000 IU per day. That's to say healthy people taking 2000 IU/day are unlikely to experience any adverse effects. Although some now are considering this to be too low, it is a well established level that would apply to most people north of California.

5. Vitamin D3 is a more active form than D2, so go with that one if given the choice. Also, it is a fat soluble vitamin, which means that if you take it with food that contains some fat (olive oil, etc..) it will help your body absorb it. For the pregnant mothers out there, be cautious with some food sources of vitamin D, as some can be harmful to the fetus. Cod liver oil for example, contains large amounts of vitamin A (which is also a steroid hormone) that can cause birth defects.

In conclusion, I want to reiterate the importance of consulting a health professional for specific advice regarding dose and form. The information presented here is intended educate on the importance of vitamin D, and to provide some basic understanding on how we get it. Hope this has been helpful,

B