A new Harvard Chan School study shows it’s the quality—not quantity—of macronutrients that make a difference for heart health, debunking myth that modulating carbohydrate and fat intake alone is inherently beneficial.
This is where the data meets an uncomfortable impasse. Hispanics in the U.S. live a lot longer than whites. It’s not because of socio-economics. Hispanics eat a lot of meat, too. It is theorised that their legume heavy diet might be responsible. Meaning that, despite eating a lot of carbs, they still live longer. I suspect longevity effects are primarily related to the fibre. This might be true in the study linked. Perhaps it isn’t the low carb/low fat part which gave heart benefits, but the higher fibre intake.
As for the mechanisms:
Fibre binds bile acids, which increases bile acid secretion. The liver uses LDL to make more bile acid, reducing LDL.
Fibre acts as a glucose release modulator. Glucose spikes are responsible for a range of immediate and systemic issues. Reducing overall glucose consumption and especially spikes results in lower risk of type 2 diabetes, metabolic syndrome, and atherosclerosis progression.
Lower blood pressure (we’re not really sure why yet).
Fermentable fibres are metabolized by gut bacteria into short-chain fatty acids. These reduce systemic inflammation, improve gut barrier integrity, improve insulin sensitivity, and regulate immune function. The inflammation one in particular could explain a great deal of the health benefits.
The cancer risk specifically decreases because of dilution and faster transit of carcinogens, SCFA production (especially butyrate, which has anti-tumor properties), and reduced insulin and IGF-1 signalling.
Fibre keeps you full for longer, reducing the risk of obesity.
Quite right, and this is the problem with correlational studies like that linked: they’re observational. We can’t do controlled studies on humans, so we try very hard to control for confounds.
This is where the data meets an uncomfortable impasse. Hispanics in the U.S. live a lot longer than whites. It’s not because of socio-economics. Hispanics eat a lot of meat, too. It is theorised that their legume heavy diet might be responsible. Meaning that, despite eating a lot of carbs, they still live longer. I suspect longevity effects are primarily related to the fibre. This might be true in the study linked. Perhaps it isn’t the low carb/low fat part which gave heart benefits, but the higher fibre intake.
As for the mechanisms:
Fibre binds bile acids, which increases bile acid secretion. The liver uses LDL to make more bile acid, reducing LDL.
Fibre acts as a glucose release modulator. Glucose spikes are responsible for a range of immediate and systemic issues. Reducing overall glucose consumption and especially spikes results in lower risk of type 2 diabetes, metabolic syndrome, and atherosclerosis progression.
Lower blood pressure (we’re not really sure why yet).
Fermentable fibres are metabolized by gut bacteria into short-chain fatty acids. These reduce systemic inflammation, improve gut barrier integrity, improve insulin sensitivity, and regulate immune function. The inflammation one in particular could explain a great deal of the health benefits.
The cancer risk specifically decreases because of dilution and faster transit of carcinogens, SCFA production (especially butyrate, which has anti-tumor properties), and reduced insulin and IGF-1 signalling.
Fibre keeps you full for longer, reducing the risk of obesity.
There can be many more factors influencing lifespan than just diet, though.
Quite right, and this is the problem with correlational studies like that linked: they’re observational. We can’t do controlled studies on humans, so we try very hard to control for confounds.
Or they just don’t eat processed crap.
I would be surprised if that were true but I haven’t seen any data either way on that.