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Low Fat consensus was wrong: High carb diets increase death rates

How many people have died prematurely because they swapped their fats for carbohydrates?

US Food, Diet, Recommended Daily intake.

More fat meant less death (left). More carbs (right) meant the opposite (at least above 60%). (Click to see the full table of Figure 1 results).

New research published in the Lancet shows that low fat diets could increase your risk of death.

Specifically, those who are in the top fifth of carbohydrate-eaters are also about 28% more likely to die than the fifth eating the lowest amount. This is a correlation (only), but the PURE* study was tracking the thing that matters most — all-cause mortality —  and they followed the diets of 135,000 people in 18 countries for 5 – 9 years.  Loosely, if people avoided high carbohydrate diets, they were less likely to die.

The graph flattens off below “60% carbs” (that’s a percentage of total calories). However, the mortality numbers keep improving for the highest fat intakes which rather skewers 40 years of headlines. I’m guessing that some people who kept carbs below 60% ate more protein instead, which, judging by the “fat” graph, wasn’t as useful.

The McMaster University team announced this quiet bomb, slightly obscured, in a press release about three papers at once under a tame headline, “Moderate consumption of fats, carbohydrates best for health, international study shows.”

Read carefully:

higher fat consumption was associated with lower mortality; this was seen for all major types of fats (saturated fats, polyunsaturated fats and mono unsaturated fats), with saturated fats being associated with lower stroke risk.

So saturated fats might reduce strokes?

Total fat and individual types of fat were not associated with risk of heart attacks or death due to cardiovascular disease.

This is not the dietary approach that 97% of experts and officials recommend.

The current government consensus, backed by thousands of scientists and doctors, and running for decades, tells people to limit fat and eat a high grain diet (which means carbohydrates). See the US Dietary Guidelines.

The message has generally been to “limit fat”, be careful with protein, and fill up all the empty spaces with carbs.

US Food, Diet, Recommended Daily intake.

The current US Food guidelines puts a big emphasis on grains (carbs).

Like the US, the Australian Guide to Healthy Eating still recommends eating a lot of grains (more than any other category).

Guideline 2 recommends  “Milk, yoghurt, cheese and/or their alternatives, mostly reduced fat. Guideline 3 tells us to Limit intake of foods containing saturated fat,

Australian experts remark that “Low fat diets are not suitable for children under the age of 2 years.” They don’t say that low fat diets may increase the risk of death in people over 2.


Australian food dietry intake, recommendations, diagram.

Grains make up the largest part of the food plate in Australian Government Recommendations. | Click to enlarge

The news that fat is no demon, will come as no surprise to people who have been looking at medical papers, internet forums, and some popular diet books for the last twenty years. (Though notably, the percentages assessed in the PURE study are not remotely “keto” levels of low carb which are in the 5% carb range and 75% fat as per the Atkins, or Keto-style diets.)

Presumably the mainstream consensus and recommendations will shift in the next 5 – 10 years to soften up on the anti-fat dogma, and start to warn people that just making your bread wholemeal doesn’t neutralize the carbs and turn it into a superfood. When will food pyramids and guiding-plates drop the non-essential “essential grains” meme?

In the meantime, the people who obediently follow the official experts can be sure that “consensus” is self correcting eventually — but the process can still be deadly.

For those who want the gritty details, the lowest quintile of carbohydrate intake ate about 46% or less of their calories from carbohydrates. The highest quintile — 77% or more. So most people won’t have a clue, (or an inclination) but if you do, there is good software available online to estimate these numbers (and a lot more). It’s easier than you think.

On saturated fats, the researchers write that things are complicated, but we appear to need some small base level:

Collectively, the available data do not support the recommendation to limit saturated fatty acids to less than 10% of intake and that a very low intake (ie, below about 7% of energy) might even be harmful.

Sat-fats might not be so bad, but at 10% of daily intake we are only talking of 20 grams a day in a 2000 calorie diet. It’s still not a lot.

On monounsaturated fats, the finding is consistent across many big studies:

We found an inverse association between monounsaturated fatty acid intake and total mortality. Consistent with our findings, two large cohort studies of the Health Professionals Follow up and the Nurses’ Health Study showed lower total mortality by higher monounsaturated fatty acid intake.46

Monounsaturated fats means olives, avocados and some nuts.

And of course things can be confounded by the fact that carbs are cheap, cheap, cheap, and maybe some people who are eating lots of carbs just don’t have the money to afford the more expensive fats and especially proteins. (Though they did adjust for income, education, wealth, etc to try to consider that).

Finally, at least they do recommend that the consensus shifts, and it’s worth mentioning that they refer to other enormous separate studies (Health Professionals Follow up and the Nurses’ Health Study) as well as some randomized trials:

Global dietary guidelines should be reconsidered in light of the consistency of findings from the present study, with the conclusions from meta-analyses of other observational studies and the results of recent randomised controlled trials.

The Abstract:

Look for HR = 1.28, meaning a 28% higher risk of dying.

During follow-up, we documented 5796 deaths and 4784 major cardiovascular disease events. Higher carbohydrate intake was associated with an increased risk of total mortality (highest [quintile 5] vs lowest quintile [quintile 1] category, HR 1·28 [95% CI 1·12–1·46], ptrend=0·0001) but not with the risk of cardiovascular disease or cardiovascular disease mortality. Intake of total fat and each type of fat was associated with lower risk of total mortality (quintile 5 vs quintile 1, total fat: HR 0·77 [95% CI 0·67–0·87], ptrend<0·0001; saturated fat, HR 0·86 [0·76–0·99], ptrend=0·0088; monounsaturated fat: HR 0·81 [0·71–0·92], ptrend<0·0001; and polyunsaturated fat: HR 0·80 [0·71–0·89], ptrend<0·0001). Higher saturated fat intake was associated with lower risk of stroke (quintile 5 vs quintile 1, HR 0·79 [95% CI 0·64–0·98], ptrend=0·0498).

Total fat and saturated and unsaturated fats were not significantly associated with risk of myocardial infarction or cardiovascular disease mortality. Interpretation 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.

Hints: Quintile means a fifth of the population. HR means “Hazard Ratio”. CI = Confidence Interval.  ptrend = statistical info, lower is more significant.

Those who want to stay healthy and strong,
And their years of existence prolong,
Should not eat like Jack Spratt,
But like Joan, choose the fat,
As the low-fat consensus is wrong.

    — Ruairi


*PURE = Prospective Urban Rural Epidemiology


Dr Mahshid Dehghan, et al (2017) Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study, The Lancet, August 2017 DOI: http://dx.doi.org/10.1016/S0140-6736(17)32252-3

Salim Yusuf, DPhil et al. (2017) Fruit, vegetable, and legume intake, and cardiovascular disease and deaths in 18 countries (PURE): a prospective cohort studyThe Lancet, August 2017 DOI: 10.1016/S0140-6736(17)32253-5

h/t Lance W. Thanks.

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