Dangers of Starch

[teo123]

Hey, guys!
So, one common argument against a vegan high-carbohydrate diet is the supposed dangers of eating starch. Some people claim that starch is, as well as sugar, more dangerous than saturated fat.
Based on what I've seen, nearly all nutritionists agree that sugar is exceptionally dangerous. However, there appear to be two streams in nutritional science explaining why:
1) Sugar digests a lot faster than starch, so it raises the glucose level in your blood a lot faster than starch does. Fructose is dangerous only if consumed in very high amounts. That explanation was included in my biology textbook, in fact, they said there that fructose is perfectly safe for people with diabetes. So, I guess that explanation is slightly more mainstream. If that is true, then I guess that fear from starch is somewhat justified.
2) Type II diabetes is caused primarily by fructose damaging the liver, not by glucose. Fructose is dangerous even in the amounts that's often consumed today, and the vast majority of fructose that's consumed today comes from sugar. Since starch is free from fructose, the fear from starch is then completely unjustified. And eating sweet fruits is somewhat dangerous, but not as much as eating sweets is, since sweets generally contain way more fructose (half of the sugar is composed of it).
So, what do you think, which one is true?
Honestly, more I study nutritional science, more confused I am. On one hand, you have quite a few high-quality studies that show that saturated fat cause heart disease, and that omega-3-fatty-acids, supposedly the most healthy form of fat, don't help against heart disease at all. On the other hand, you have studies that show that replacing starch with either saturated or unsaturated fat protects against heart disease. On one hand, you have people telling you optimal diet includes very little protein, just enough to get all the essential amino-acids, because human milk contains remarkably little protein. On the other hand, there are studies that show that increasing the amount of energy that comes from protein from 15% to 35% decreases the risk of diabetes. On one hand, you have studies showing that a high-fat diet causes diabetes. On the other hand, you have studies showing it cures diabetes. And you have people telling you not to eat less than 135 grams of carbohydrates per day even if you have diabetes because a diet low in carbohydrates causes cognitive problems and kidney stones. On the other hand, you have people telling you the cognitive problems caused by low-carbohydrate diets are temporary, and that even a very low-carbohydrate diet doesn't cause kidney stones as often as an average diet causes diabetes. And many times, it's very hard to tell what the consensus is.

[cornivore]

A committee on Carcinogens and Anticarcinogens in the Human Diet concluded that "macronutrients and excess total calories present the greatest dietary cancer risk in the United States".

So apparently the consensus would be don't eat too much of any macronutrient (they're all dangerous that way). Whatever diseases they may be associated with are usually do to overnutrition.

[brimstoneSalad]

There's no reason to believe starch is worse than saturated fat; or even that sucrose or fructose sugar is.

1) Sugar digests a lot faster than starch, so it raises the glucose level in your blood a lot faster than starch does. Fructose is dangerous only if consumed in very high amounts. That explanation was included in my biology textbook, in fact, they said there that fructose is perfectly safe for people with diabetes. So, I guess that explanation is slightly more mainstream. If that is true, then I guess that fear from starch is somewhat justified.

Glycemic index is complicated. Absorption is also slowed by coarser grain flours and presence of fiber. If you're just eating a bunch of literal starch (e.g. corn starch) that's different from the starch IN a whole grain flour, and that's different from the starch in whole vegetables or un-ground grains.

Focusing only on glucose vs. fructose concentration isn't terribly helpful because rate of blood sugar spike is principally based on microscopic structural factors.

ALSO, there's no very compelling reason for non-diabetics to fear blood sugar spikes on their own. However, that said, rapidly spiking and falling blood sugar may have side effects on hunger and appetite and result in more frequent and over-eating.
It's possible that a steadier blood sugar could help some people lose weight... although there's not a lot of good evidence on that.
It is true that lower glycemic plant based foods will normally correlate with healthier ones.

So basically... doesn't seem to matter much. If you're erring on the side of caution totally eat moderate on glycemic index, and it might be beneficial, but your main benefit will probably be in that heuristic keeping you away from junk foods.

2) Type II diabetes is caused primarily by fructose damaging the liver, not by glucose.

Well that's probably bullshit.

Fructose is dangerous even in the amounts that's often consumed today, and the vast majority of fructose that's consumed today comes from sugar.

That probably is true, though. Thanks to high fructose corn syrup and to sucrose as well, people eat inordinate amounts of fructose and not everybody's genetics are going to be able to handle that well.

Since starch is free from fructose, the fear from starch is then completely unjustified.

The fear of either directly causing diabetes is unjustified, but you can rest assured that starches are liver safe and glucose is metabolically safer and healthier than fructose in larger amounts.
I can not think of any reason fructose would be inherently better than glucose unless you're a diabetic, and even then just consuming starch in a way that is more gradually digested may still be better.

And eating sweet fruits is somewhat dangerous, but not as much as eating sweets is, since sweets generally contain way more fructose (half of the sugar is composed of it).

Fruits contain a bunch of health promoting phyto-chemicals. The fructose isn't good for your liver above a certain minimal amount that your liver can handle without stress, but the other nutrients in fruits may make them worth it. I think it's safe to say they're better than sugar which provides essentially nothing but calories.

On the other hand, you have studies that show that replacing starch with either saturated or unsaturated fat protects against heart disease.

Please link what you're talking about. These are probably dealing with refined grains, white flour, white rice, etc.
There is no consensus on the inferiority of starch in food to saturated fat, but it's pretty close when it comes to empty calorie sugar and starches like white rice that aren't much better.

On one hand, you have people telling you optimal diet includes very little protein, just enough to get all the essential amino-acids, because human milk contains remarkably little protein.

Breast milk contains a large amount of protein per kg body mass that consumes it. Either way, that's a silly argument because nothing about breast milk/formula or infant development should say anything about adult nutrition beyond the fact that human beings can clearly absorb the "artificial" nutrients in formula just as well (the only evidenced benefit of breast milk is immune based).

That said, it probably is metabolically ideal for longevity to eat less protein, but the same benefits can be seen from restricting only methionine rather than all protein consumption. *Most* plant proteins contain a lower proportion of methionine.

On the other hand, there are studies that show that increasing the amount of energy that comes from protein from 15% to 35% decreases the risk of diabetes.

Of course it would; protein is satiating and eating more protein usually means eating fewer calories. Being over weight is the largest risk factor.
You'd have to link me to the study showing what they're controlling for.

On one hand, you have studies showing that a high-fat diet causes diabetes. On the other hand, you have studies showing it cures diabetes.

High fat diets can both cause weight gain or weight loss depending on how they are administered. However, there's no obvious evidence of superiority of fat vs. carbs when it comes to dietary plans; restricting either seems helpful, and perhaps just because it makes food less appealing.

There's a big difference between a diet filled with fried food that's high fat because of that and a diet rich in e.g. nuts that fill people up and help them lose weight.
You can't isolate a nutrient like that without controls.

Either way, there's no good reason to think the fat is directly doing anything. Or carbs for that matter.

And you have people telling you not to eat less than 135 grams of carbohydrates per day even if you have diabetes because a diet low in carbohydrates causes cognitive problems and kidney stones.

It is a bad idea to eat a keto diet long term unless medically necessary (like for some kinds of epilepsy). We don't know much about the long term harms because the trend of people eating keto long term is very new. Kidney stones would be the least of the concern.

It should be some indication that people who have historically eaten very low carbohydrate diets have evolved genetics to make it more difficult or impossible for them to go into ketosis.

As long as you're not in ketosis, any low amount of carbs is probably fine. Depends on your genetics. They have test strips that you pee on or something to check. Just stay out of ketosis would be the only thing to consider for minimum carbs. For some it may be as low as 50g or so.

On the other hand, you have people telling you the cognitive problems caused by low-carbohydrate diets are temporary,

Possibly, but also Anecdotal from advocates of those diets. And it's an anecdote that's much harder to measure or confirm; more likely they just adapted to a state of impairment and no longer notice it.

That's not like vegans saying you fart less after you've been eating beans and broccoli for a few months; something with evidence, mechanism of action, and that's very easy to confirm. Also you can just take "beano" if it's a problem, and gas (unlike cognitive impairment) is not likely evidence of a threat to health but can instead be evidence of a healthy microbiome.

and that even a very low-carbohydrate diet doesn't cause kidney stones as often as an average diet causes diabetes.

That's dubious.

They may appear metabolically healthy, but ketogentic diets result in hepatic insulin insensitivity called "starvation diabetes"; it's not clear what the long term effects of this are or if it might actually increase risk of developing type II diabetes.

That said, if you're not over weight and you eat fairly well you're very unlikely to develop type II diabetes unless it's really common in your family. Probably much less likely to develop diabetes than you would be to develop kidney stones from a keto diet where it wasn't warranted.