Dietary carbohydrates are usually thought of as healthy or at worst benign, and current dietary guidelines suggest eating plenty of carbohydrates, especially grains. But are carbohydrates really healthy or benign, or do they harm health and promote aging? As we’ll see below, dietary carbohydrates promote aging.
Dietary guidelines specifically call for eating whole grains, and we’ve been bombarded with messages that eating them is the healthy thing to do.
However, there’s little evidence that whole grains provide any benefits.
The evidence that does exist is mostly epidemiological, that is, the evidence consists of associations between better health and the use of whole grains. (Overview of the evidence here.) As with other studies showing associations, causality cannot be shown. People who eat whole grains are likely to smoke less, exercise more, be more health conscious, have higher IQ and higher conscientiousness, have lower prevalence of obesity – in short, to be motivated to be healthy and take steps to be so. This is the healthy user effect. It’s difficult to separate any effects of whole grains from the other factors.
Randomized controlled studies are the gold standard for showing causality. And meta-analyses done by the Cochrane group are the gold standard for ascertaining the validity of scientific evidence.
A recent Cochrane meta-analysis of randomized controlled trials of whole grains in relation to cardiovascular disease risk found:
There is insufficient evidence from RCTs of an effect of whole grain diets on cardiovascular outcomes or on major CVD risk factors such as blood lipids and blood pressure. Trials were at unclear or high risk of bias with small sample sizes and relatively short-term interventions, and the overall quality of the evidence was low. There is a need for well-designed, adequately powered RCTs with longer durations assessing cardiovascular events as well as cardiovascular risk factors. [Emphasis added.]
If whole grains have no effect on cardiovascular risk, it seems likely that other health effects would be minimal to non-existent.
In truth, whole grains may have some benefit depending on what they displace in the diet. For example, whole grains have a lower glycemic index than refined grains, so if a person ate whole instead of refined grains, that could be beneficial.
But, since whole grains increase insulin response and raise blood sugar, cutting them out of your diet entirely would make more sense.
In any case, the lack of evidence of benefits for cardiovascular disease in controlled trials makes a travesty of the allegedly “evidence-based” dietary guidelines. Health authorities should not be subjecting the American people to a massive dietary experiment without extremely good evidence that what they recommend is healthy. Instead of healthy, we got the obesity epidemic.
High carbohydrate intake was associated with higher risk of total mortality, whereas total fat and individual types of fat were related to lower total mortality. Total fat and types of fat were not associated with cardiovascular disease, myocardial infarction, or cardiovascular disease mortality, whereas saturated fat had an inverse association with stroke. Global dietary guidelines should be reconsidered in light of these findings.
The charts below show associations between the amount of energy in the diet from total fat, different types of fat, and carbohydrates, in relation to total mortality and cardiovascular mortality.
Fat was protective, carbohydrates were harmful. To be fair, one must point out that the percentage of carbohydrate that showed higher death rates was very high, above 65% of calories. Currently, Americans eat about 50% of calories as carbohydrates. In the PURE study, more than half the subjects ate 60% or greater carbohydrate, and one quarter ate more than 70%.
These results, like other similar studies, show an association only, but in this case the association shows the opposite of what health authorities believe.
Most carbohydrates consist of long chains of glucose molecules, which means that when broken down by digestion, glucose results. Carbohydrates raise blood sugar and insulin levels, and this process is related to aging and greater mortality.
Taking the body of preceding evidence both from model organisms as well as human epidemiology into account, we therefore believe that current nutritional recommendations in regards to macronutrients, but most importantly in regards to refined carbs and sugar, should indeed be fundamentally reconsidered.
Ketogenic diets are characterized by very low to zero carbohydrate intake, which results in the production of ketones.
Ketogenic diets extend lifespan in lab animals, and even ketone supplements do so. More recent studies have found the same: ketogenic diet extends longevity and healthspan in mice.
Ketogenic diets may extend lifespan because they generate ketone bodies, or because they lower blood sugar and insulin, or because of all of these, or conceivably because of other additional factors. The fact that ketone bodies mimic calorie restriction, the most potent lifespan-extending intervention known, argues that ketone bodies themselves are the magic ingredient.
Aging can be defined as a tendency to worse health
Carbohydrates, at least in sufficient amounts, worsen health. Ergo, carbohydrates promote aging.
While ketogenic diets are beneficial, any carbohydrate restriction is beneficial, so you don’t need to go ultra-low to zero carbohydrate to reap the benefits, although it certainly appears that very low carbohydrate ketogenic diets offer the most benefit.
Sugar is arguably the worst carbohydrate for health, so eliminate that first.
I discussed a very low carbohydrate diet as a cornerstone in fighting aging in my book, Stop the Clock.