Finally! Some clear-minded scientists are recognizing the limitations of government data on nutrition and health. Limitations I’ve been telling you about here in the Daily Dispatch, in my Insiders’ Cures newsletter, as well as writing about them for 30 years. Namely, the following:
- Most government research is based only on what people say they eat, instead of observing what they actually consume (see “Garbage In, Garbage Out”).
- Most government research is not based upon measuring actual levels of nutrients in the blood. (And even blood levels don’t necessarily reflect levels in the tissues, which is where the “action” happens, so to speak.)
- Most government research focuses solely on the quantity of those nutrients, not the quality.
With these facts in mind, an insightful group of scientists decided to take a second look at the association between fruit and vegetable intake and breast cancer. An association that’s been persistently weak in past epidemiologic studies.
The researchers chose to investigate how errors in the assessment of how much fruit and vegetables people ate may actually have led to unclear results.
So this time, they took blood samples from the study participants. They measured carotenoid concentrations in order to get a more clear measurement of actual fruit and vegetable intake. This approach replaced the dietary questionnaires “nutritional epidemiology” typically relies on.
In my report Classified Cancer Answers, I wrote about a similar case of weak associations between the consumption of certain nutrients and cancer. An early study showed a weak association between vitamin A and beta-carotene levels in the blood for lung and certain other cancers. But one of the main problems with the big, misbegotten National Cancer Institute trial on beta-carotene and lung cancer was they simply ignored that the dietary studies were actually telling them that it is other carotenoids (not beta-carotene), and other nutrients—like vitamin C—that are important. Despite my attempts to point out to them, “you’ve got the wrong guy!”
While that lung cancer trial using isolated, synthetic beta-carotene was a bust, lung and breast cancer remain the two biggest cancers in women. And there is a big difference between getting your nutrients from whole-food sources, like fruits and vegetables, and taking a pill. Especially an arbitrary dose of a synthetic, isolated nutrient pill like beta-carotene.
So, when it comes to the whole vitamin and carotenoid story… looking at actual nutrient intake and nutrient levels in the blood may finally start to get us somewhere.
But until now (over 20 years later!) no systematic assessment has compared dietary intake with blood concentrations of carotenoids and breast cancer risk. Which makes this recent study, published in the American Journal of Clinical Nutrition, truly something new.
Overall, the researchers concluded that blood concentrations of carotenoids are more strongly associated with reduced breast cancer risk than are carotenoid intakes assessed only by dietary questionnaires.
They suggest that the use of nutrient biomarkers in the blood may help clarify the weak and inconsistent results between dietary intake and breast cancer risk assessed only by questionnaires.
These results confirm what I’ve been saying all along—that relying only on people’s own flawed accounts of what they eat is rarely an accurate way to study nutrition. And the fact that almost all the expensive research done until now has used this crude method may explain inconsistent and weak results between dietary intake of nutrient-containing foods and breast cancer risk.
The picture is finally becoming clearer, now that someone has actually taken the trouble to measure these nutrients in the blood.
So what does all of this mean for you?
It means you should work on increasing your blood levels of carotenoids and nutrients. And the best way to do that is to keep eating those green, leafy vegetables. They are great sources of most carotenoids, as well as B vitamins, vitamin C, healthy fiber, some calcium, and many other beneficial, bioactive plant constituents.
The biological reality of increasing breast cancer rates in our modern world is this: Other than having more children as early and often as you can, and breastfeeding them for as long as you can, a healthy diet remains the best natural strategy for preventing breast cancer.
“Dietary compared with blood concentrations of carotenoids and breast cancer risk: a systematic review and meta-analysis of prospective studies.” Am J Clin Nutr 2012; July 3 (epub ahead of print)