Have we really examined the long term effects that regular and significant consumption of starchy tubers has on the pancreas?
My reason for asking is quite personal. My mother died at the ripe old age of 45 from pancreatic cancer (many consider this to be the most deadly cancer of all). Since I eat starchy carbs, I figured it might be important to get this one right.
Are we working our pancreas overtime to secrete insulin when too many carbs are consumed? Might this be applicable when eating sweet potatoes and/or a big helping of white rice on a regular basis?
asked byJack_Kronk (18452)
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on July 06, 2011
at 07:05 PM
I'll try to provide a balanced perspective on this based on what I know. If you examine human history, you realize that most hunter-gatherer diets were starch-based. The so called Paleolithic diet based on ice-age, carnivorous hunters that hunted mammoths and only infrequently ate root vegetables and berries is a complete myth.
The "gatherer" part of the hunter-gatherer is often misunderstood. The most widely-consumed food group was vegetables, i.e., starchy tubers like cassava, potatoes, sweet potatoes, yams, taro, turnips. Even after the advent of agriculture, these crops were consumed widely based on geography, along with agricultural crops such as corn, rice, and wheat.
The insulin response from eating such tubers is automatic and natural. In a healthy person, the 2h post-prandial should fall to the fasting level (mid-80s in a healthy person). No record of diabetes exists for those indigenous peoples that have eaten traditional, starchy-based diets. Not even for the Tarahumara and Pima Indians who subsited on corn and whose carbs percentage was around 85%.
Such peoples typically display very low fasting BS levels. The Khitavans and New Guineasn who eat 80%+ starchy carb diets are in the low 80s and their 2h PPs fall to that level, actually sooner than 2h, mostly at 90 minuntes. See Stephan Guyenet's blog about the fasting BG and insulin in such peoples.
Conclusion: If you're gluten-free and minimize sugar/fructose and avoid Omega 6s, a starchy diet will not overwork your pancreas. Blood sugar surges after a starchy meal is normal. This only becomes a problem if your metabolism is wrecked.
Addendum: I've noticed that if you eat pure starch like yuca and yams, and completely abstain from processed foods, you tend to regain your insulin sensitivity. Having eaten 100-150gs of yams, I'm back to a fasting level of mid-90s (good enough for me) within 2 hours. In actuality, the post-prandial may actually dip below 85 in some cases (perhaps hyper insulin sensitivity?)
So what's happening?:
High carbs ==> High BG ===> Insulin Spike ==> Carcinogenesis, diabetes, heart disease, autoimmunity, etc. Elevated insulin is implicated in all these and we're told that:
Low Insulin ==> Longevity and Slow and Graceful Aging.
However, it's not that simple. With the above safe starches, I'm beginning to think there is an additional mechanism at work which enhances and promotes one's insulin sensitivity.
Safe Starchy Carbs ==> Temporary BG Elevation Followed by an Insulin Response ==> Lower Than Usual Post Prandial and also Lower Fasting BG ==> More Efficient and Effective BG Management and Overall Higher Insulin Sensitivity
In fact, it's not even clear whether there's really higher insulin level in a safe-starch diet than in a low-carb or VLC diet. Perhaps the spikes are not only temporary but fleeting and the enhanced insulin sensitivity more than compensates by promoting lower post-prandial and fasting BGs.
That is my hunch and hypothesis. I'm a T2 diabetic and notice this, so there is much more to learn in this area.
on July 06, 2011
at 05:49 PM
If one is metabolically healthy I doubt an organ can be over worked. Derangement, disease, etc are the primary causal factors for organs not performing at 100% peak efficiency. The human body is incredibly robust and adaptable, hence the success of humans but this strength can also be a weakness in that the body can adapt to abuse and not show any overt signs until it gets to a threshold and cannot take anymore.
on July 06, 2011
at 06:10 PM
Jack Im upvoting this because I think this question is at the foundation of why many Paleo folks hit stalls........they dont understand where they are biochemically in their health. I think many can eat tubers and starches when they are humming along......but as we know many find paleo how are trying to get right. That is why I am always asking about context. Most of the people I see who want to make an initial change should not be eating this stuff......Im glad you went there.