Absorption of nutrients and fat

[Concerned]

I know it might be to late to submit another question for the Dr. Fuhrman/Dr. McDougall debate, but I am troubled by this question. (I have read the threads that relate to it.)

I recently saw a video on Dr. Greger's website in which he reviewed a study which checked blood levels of antioxidents (or other nutrients, I don't remember) for about 10 hours following the eating of a salad. The people who ate their salad with fat free dressing absorbed almost no nutrients from it! Dr. Greger said it would have been enough to eat only 5 walnut halves with the salad in order to get high absorption.

So, is this just one isolated study? Could it be that people who regularly eat a very low fat diet adjust and acquire the ability to absorb nutrients even with low levels of fat intake? How could it be that people who are healthy after years of low fat intake are not absorbing many nutrients from their salads?

Should we just make certain to eat our flaxseed or a few nuts, if we plan to eat them, with our vegetables so as to get the maximum effect from them?

Thanks!

[JeffN]

First,

http://www.drmcdougall.com/forums/viewtopic.php?t=5939

And more importantly...

Absorbing more doesn't automatically equate to better health outcomes.

Speaking of health outcomes, which is what really matters, lets put all of this into proper perspective.

From

"'Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids', Food and Nutrition Board. Institute of Medicine. National Academy Press, Washington D.C. Pp. 343-344 (2000)"

http://www.nap.edu/openbook.php?record_id=9810&page=353

"These data, although in varying populations, suggest that 3 to 6 mg/day of β-carotene from food sources is prudent to maintain plasma β-carotene concentrations in the range associated with a lower risk of various chronic disease outcomes (see Table 3)."

Table 3:

http://www.nap.edu/openbook.php?record_id=9810&page=341

As just detailed, plasma and tissue concentrations of carotenoids have been associated with a variety of health outcomes; that is, higher concentrations are associated with a lower risk of cancer, coronary heart disease, and all-cause mortality. This could be used as a possible indicator for establishing requirements for carotenoids. However, the limitation of this approach is that it is not clear whether observed health benefits are due to carotenoids per se or to other substances found in carotenoid-rich foods.

Thus, these data are suggestive of prudent intake levels, not required levels of intake. Recommendations have been made by a number of federal agencies and other organizations with regard to fruit and vegetable intake. Nutrient analysis of menus adhering to the U.S. Dietary Guidelines and the National Cancer Institute's Five-a-Day for Better Health Program, for example, indicates that persons following these diets would be consuming approximately 5.2 to 6.0 mg/day provitamin A carotenes on average if a variety of fruits and vegetables were consumed (Lachance, 1997). Similar levels would be obtained by following Canada's Food Guide for Healthy Eating which specifies a minimum of five servings of vegetables and fruit (Health Canada, 1997). Other food-based dietary patterns recommended for the prevention of cancer and other chronic diseases would provide approximately 9 to 18 mg/day of carotenoids (WCRF/AICR, 1997).

NOTE: this is 3-6x the amount recognized as being enough to lower disease risk

It is also based on the WCRF/AICR report from 1997. In many other discussions here, I have quoted the WCRF/AICR newest report from 2007 saying that they now more than ever, recommend dietary "patterns" over recommending specific "individual foods".

So, in other words, if Americans would just get in the recommended amounts of fruits and veggies, it would not only provide carotenoids, but more than enough of all of them to produce the beneficial health outcomes, including reduced risks of cancer. And anyone following a Whole Food plant based diet, as recommended here, would already be consuming WAY more than enough.

Of course, the real issue is why do you have to increase the absorption of raw veggies (which are very low) when you can just cook them (which increases absorption), or just eat cooked tubers, which have almost the highest absorption rate, as is.

http://www.nap.edu/openbook.php?record_id=9810&page=354

In Health
Jeff

[Concerned]

Thank you. That was very interesting.

Regarding absorption of nutrients from salads: I would think that although we might absorb certain nutrients from tubers (meaning sweet potatoes, or others as well?), there are other nutrients which are more available from salads (ie, raw greens, peppers etc.). I thought raw vegetables are a vital component of a healthy diet.

I wonder if an experiment using subjects who habitually eat a lowfat plant based diet would show different results: that these people had adjusted and were able to absorb nutrients from a lowfat salad as well as from a salad with some fat.

In any case, thank you for the valuable information as always!

[ETeSelle]

Regarding absorption of nutrients from salads: I would think that although we might absorb certain nutrients from tubers (meaning sweet potatoes, or others as well?), there are other nutrients which are more available from salads (ie, raw greens, peppers etc.). I thought raw vegetables are a vital component of a healthy diet.

Green and yellow veggies are, of course. But there is no reason why they have to be raw. Cooked veggies are better used by the body, after all.