"The co-consumption of two servings of cooked broccoli with your mashed potatoes would certainly do it, immediately cutting the insulin demand by nearly 40 percent."

"Simply chilling potatoes may cut down on the blood sugar and insulin spikes, but to get significant drops in both, you just have to add about a tablespoon of vinegar to drop levels by 30 to 40 percent."

Even just yellow potatoes like Yukon gold may be preferable to white, but the best may be purple potatoes: not just purple-skinned potatoes, but purple-fleshed potatoes. If you've never seen purple potatoes, they are remarkable; they have almost a neon blue glow. And not only do they look cool, but purple potatoes cause less of an insulin and blood sugar spike compared to even the yellow-fleshed potatoes, suggesting that switching from yellow or white to purple could have a large potential public health benefit.

"Deeply colored fruits and vegetables (eg, leafy greens, peaches) tend to be more nutrient dense than lighter colored and white fruits and vegetables.[31]"

First, though, they looked at regular potatoes, white russet potatoes. One steamed potato a day for six weeks. Inflammation, as measured by C-reactive protein levels in the blood, tended to go up. Next, potatoes with yellow flesh did a bit better. But neither were significantly different than baseline. Only purple potatoes, potatoes with purple flesh, significantly decreased inflammation.

And the same thing was found for oxidation. In this 2012 study, within hours of consumption, purple potatoes increased the antioxidant capacity of one’s bloodstream, whereas white potato starch appeared to have a pro-oxidant effect.

And purple potatoes also appeared to help lower blood pressure in folks with hypertension. They put people on six to eight small microwaved purple potatoes a day, and concluded “purple potatoes are an effective hypotensive agent and lower the risk of heart disease and stroke in hypertensive subjects without weight gain.”

Combined with the reduction in inflammation and DNA damage, purple potatoes offer “consumers an improved nutritional choice in potato consumption.”

When regular starches are cooked and then cooled, some of the starch recrystallizes into resistant starch. For this reason, pasta salad can be healthier than hot pasta and potato salad can be healthier than a baked potato, but the effect isn't huge. The resistant starch goes from about 3 percent up to 4 percent.

Choosing lower-glycemic foods may help promote weight loss, but timing is critical. Due to this circadian pattern in glucose tolerance, a low-glycemic food at night can cause a higher blood sugar spike than a high-glycemic food eaten in the morning. We’re so metabolically crippled at night: researchers found that eating a bowl of All Bran at 8pm caused as high a blood sugar spike as eating Rice Krispies at 8am. High-glycemic foods at night would seem to represent the worst of both worlds. So, if you’re going to eat refined grains and sugary junk, it might be less detrimental in the morning.