Are White Rice and White Potatoes Harmful To Your Health?

Updated on November 13, 2019

To continue where we left off in last week's newsletter, I'd like to share what I've learned over the years about eating white rice and potatoes.

I've found that it's generally true that eating rice and potatoes decreases cellular sensitivity to insulin, leading to higher blood glucose and a tendency to carry extra adipose tissue. These tendencies seem to grow with age, and at this point, we don't fully understand the biochemistry behind this - we can only state that as we age, skeletal muscle cells usually become less sensitive to insulin while fat cells become more sensitive to insulin, which leads to more uptake of glucose into our fat cells, fuelling their growth.

So after we stop growing (at about 25 years in for most of us) and as we age, our health and longevity are well served by making dietary choices that don't lead to sharp spikes in blood glucose. This is why many health professionals recommend avoiding potatoes, rice, and foods made with flour, all of which tend to lead to a rapid rise in blood sugar.

Less well known in health and nutrition circles is that cooling cooked rice and potatoes increases their content of what's called resistant starch, which can actually help slow the rise in blood sugar that occurs after a substantial meal. This holds true even when cooled white rice and potatoes are re-heated - resistant starch content remains after one cooling.

Foods that are rich in resistant starch are processed slowly by countless bacteria that live in our gut, so contrary to popular belief, eating such foods doesn't lead to unhealthy spikes in blood sugar.

To be clear, drinking a can of Coke or even a glass of freshly squeezed orange juice invariably leads to a rapid rise in blood sugar. But foods rich in resistant starch travel to the large intestine without contributing to much of a rise in blood sugar, and in the large intestine, the fiber in these foods remains undigested, which leads to some degree of natural fermentation, leading to fortification of health-enhancing colonies of beneficial bacteria and production of beneficial compounds like short-chain fatty acids (SCFAs).

For the reasons above, foods like cooled white rice and cooled white potatoes actually improve mineral absorption and increase elimination of exogenous and endogenous toxins that we are inevitably exposed to on a daily basis.

Biochemically, resistant starch is made up of long straight chain polysaccharides, and it's the fermentation of these polysaccharides and resultant production of SCFAs like sodium butyrate that supports the health of all of our organ systems and ultimately lowers our risk of most types of cancer.

If you wish to travel down this rabbit hole of information on resistant starches and their effect on blood sugar, the gut microbiome, and short-chain fatty acids, there is a plethora of information available at PubMed. Here are some links to get you started if you wish:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5729884/

https://www.ncbi.nlm.nih.gov/pubmed/27887954

https://pubs.acs.org/doi/abs/10.1021/jf904583b

If you prefer the take-home points blended with my general suggestions, here they are:

1. When your appetite calls for white rice and white potatoes, make them beforehand and let them cool. It's fine to re-heat them before eating.

2. Generally, it's better for your energy level and quality of sleep to eat white rice and potatoes in the evening before bed rather than earlier in the day.

3. Before eating any substantial meal, aim to do some exercise, even if it's as little as 3 sets of 10 body-weight squats and a few push-ups while on your knees. A brisk walk or a more intense cardio workout are also beneficial. Any such physical activity will increase the insulin-sensitivity of your skeletal muscle cells, which will encourage shuttling of glucose from the foods you eat into your muscle cells rather than into your fat cells.

4. When you eat cooled white rice or white potatoes, eat them with other foods that are rich in healthy fats. Avocados, olives, organic eggs, and cold-water fish like wild salmon are all good choices. The healthy fats in these foods will further promote healthy blood sugar regulation and insulin sensitivity.

5. As general principles regardless of what you eat, strive to eat only when you are hungry, and when you do eat, chew your foods until liquid and with a grateful spirit - these are simple habits that yield substantial health benefits that science likely won't be motivated to measure and document any time soon. But we don't need experiential information to be in PubMed for us to benefit from it, do we?