The 'trends' are confused by the constant use of metastudies, so that the same studies can be recycled over and over.
Another way of looking at it is that metastudies
themselves indicate trends in a lot of
different studies.
Here is a lecture from [Professor Salim Yusuf]
All very interesting. As I wrote in an earlier post, I am neither an expert nor particularly well-read in this field - and I think we non-experts should be cautious in our claims, so take this for whatever it's worth - but here are a few comments and alternative perspectives anyway:
The results of Dr Yusuf's PURE study have to be put in an overall context: other experts have come to different conclusions based on other studies - including the Seven Countries Study (SCS) by Dr Ancel Keys, the dismissal of which by Dr Yusuf you seem to endorse:
Professor Salim Yusuf referred near the end of his talk to the 7 countries study. This was a study by Ancel Keys who took data on the average saturated fat intake from about 20 countries, together with their heart attack risk (which varies quite a lot from country to country) and selected just 7 data points - leaving out those that did not agree with his hypothesis that saturated fat caused heart attacks (more generally cardiovascular disease). He omitted countries such as France, which consumes a lot of saturated fat, and has low heart disease rates! This study was the original basis for the condemnation of saturated fat, even though some other researchers discovered the cherry picking and published it just two years later.
Here, Professor Salim Yusuf was wrong, for which he
apologised.
Several of the ways in which Professor Yusuf and/or you (in the above quote) go wrong in a
major muddle here are:
- The graph on which the claim of "cherry-picked data" is based had nothing to do with the Seven Countries Study from which Dr Ancel Keys concluded that there is a causal relationship between saturated fat and cardiovascular disease. The graph was published in a paper years prior to the Seven Countries Study, and that paper was part of Dr Keys's motivation for conducting the Seven Countries Study in the first place: so as to refine his developing hypothesis. Nor was the graph the only piece of evidence that he furnished in that earlier paper.
- The graph contained six countries, not seven.
- In the Seven Countries Study itself, there really were only seven countries involved, and no countries were omitted from the analysis.
- The (six-country) graph at the centre of these claims anyway plotted overall fat intake, not saturated fat intake, so it could not anyway have been the basis of Dr Keys's (later) hypothesis about saturated fat: that (later) hypothesis came out of the (later) Seven Countries Study, which had allowed him to refine his original ideas.
- The basis on which Dr Keys omitted country data from that earlier graph was not its level of disagreement with his hypothesis but its unreliability at the time (1952). Among other reliability considerations was that "numerous scientists had noticed that WWII had changed not just total mortality statistics, but coronary heart disease death rates as well, and that countries occupied by Germany during the war experienced significant upheavals to traditional diets that altered their risk factors for heart disease".[1]
- When the additional (less reliable, in Dr Keys's view) available data for other countries was included (by the other researchers whom you note responded to his paper two years later), the correlation between (overall) fat intake and heart disease, whilst substantially weakened, was not eliminated. But just to reiterate: this was not the basis of Dr Keys's (later) hypothesis about saturated fat anyway.
- In the Seven Countries Study itself, France was invited to participate: "Dr. Jacques Carlotti, a physician from Paris, was part of the pilot study team in Nicotera, Italy. Ultimately, representatives from France decided not to participate, possibly due to lack of desire, lack of funding, or both. There was no explicit intent on the part of the American SCS researchers to include or exclude France" (quoting again from the same paper; emphasis in the original; footnotes elided).
- In any case: "The “French Paradox” did not yet exist. [...] [T]he data available in the early and mid 1950s about the French diet did not suggest that people of France had either an atypical diet or heart disease profile. Quite simply, even if Keys and colleagues had been inclined to act on bias, there would have been no basis at the time for a bias against the participation of France" (same paper; footnotes elided; editing brackets and emphasis mine).
- In that (earlier, six-country) graph at issue, data for France was excluded due to the same concerns over reliability mentioned earlier: "France was one of the many European countries occupied by Germany during World War II, and thus experienced an extended period of dietary deprivation. As in much of Europe, staple foods including animal foods and dairy were rationed and supplies decreased throughout the war, in both Vichy and occupied France. Rationing was stopped only in 1949 as France — like much of occupied Europe — struggled to recover after the war’s end. Perhaps unsurprisingly, the food availability data for France in the late 1940s and early 1950s was not of the highest quality" (same paper; footnotes elided).
You refer to this as a "scandal". The scandal is the proliferation of scurrilous misinformation about Dr Keys and his work.
In any case, the paper from which I've been quoting (
[1] again) goes on to offer this observation (emphasis mine):
In North Karelia, Finland, where the SCS findings and the work of Ancel Keys were used directly and with fidelity as the basis for intervention at the community level, heart disease rates plummeted over 80% in the decades that followed, and average life expectancy increased by a full ten years. There, too, along with other changes, calories from dietary sources of saturated fat, especially dairy fat, were replaced largely with dietary sources of unsaturated fats.
Going back to an earlier post:
you should listen to Professor Timothy Noakes
OK. I watched that video. It makes too many claims for me to fact-check them all, but here are a few comments (all quotes are direct transcriptions - by me - from the video):
Professor Noakes expresses this conclusion: "
Since it is the only intervention that addresses all risk factors, the single most important intervention in the management of coronary heart disease and diabetes is to reduce the amount of carbohydrate in the diet".
This conclusion is at odds with the published research findings of others.
With respect to coronary heart disease, Dr Caldwell B Esselstyn has
conducted research into the effects of a wholefood, plant-based diet on those with preexisting cardiovascular disease (CVD). His 2017 paper
A plant-based diet and coronary artery disease: a mandate for effective therapy offers a summary of one of his early studies (editing notes and emphasis mine):
After 12 years, we reviewed the CVD [cardiovascular disease] events of our 18 adherent patients. During the eight years prior to entering our study, while in the care of expert cardiologists, they had sustained 49 cardiac events, which was indicative of disease progression. In contrast, 17 of the 18 patients sustained no further events during the 12 years they spent in our study. One patient who was initially adherent developed angina and required bypass surgery six years after resuming a Western diet. These findings illustrate the need for close adherence with WFPBN [whole food, plant-based nutrition].
He then summarises a more recent study (footnotes elided; editing notes and emphasis mine):
In 2014, we conducted a second larger study of 198 patients with significant CAD [coronary artery disease]. Of these patients, 119 had undergone a prior coronary intervention with stents or by- pass surgery, and 44 had a previous heart attack. There were multiple comorbidities including hypercholesterolemia, hypertension, obesity, and diabetes. During four years of follow up, 99.4% of the participants who adhered to WFPBN [whole food, plant-based nutrition] avoided any major cardiac event including heart attack, stroke, and death, and angina improved or resolved in 93%. Of the 21 non-adherent participants, 13 (62%) experienced an adverse event. When comparing these results to the well-known COURAGE, and Lyon Diet Heart Study, which consisted of conventionally treated participants, there is beyond a 30-fold difference in major cardiovascular events favoring WFPBN [whole food, plant-based nutrition].
As Dr Campbell notes of this study in the video shared below, the adherents to the wholefood, plant-based diet tended to decrease their reliance on statins, whereas the non-adherents didn't, so the comparison of 99.4% to 38% (100% minus 62%) for occurrence of major cardiac events probably doesn't even capture the full extent of the dietary effect.
As you know, a wholefood, plant-based diet is very low in saturated fat - any coconut fats/oils aside - and relatively high in carbohydrates.
Dr Dean Ornish has published similar results to Dr Esselstyn.
And with respect to diabetes, the published research of, for example, Dr Neal Barnard - to which I linked in an earlier post - similarly contradicts Professor Noakes's claim.
Professor Noakes's claim is also at dramatic odds with the observation that the traditional diet of the Okinawans, whose life expectancy is among the highest in the world, and who have a low incidence of age-associated diseases,
including cardiovascular disease, consists in
85% carbohydrates by energy.
[2]
Professor Noakes also claims that "
obesity is purely a marker of a high carbohydrate diet in somebody who's insulin resistant" and that "
if you are morbidly obese you have to get down to 25 grams [of carbohydrate] a day and you have to stay there for life" otherwise you will not lose weight. He does admit of the graph that he presents in support of this claim though that "
we don't have the scientific proof this is true".
It would be surprising if he did have this proof, because his claim - at least as an absolute - seems to be contradicted by the published findings of other researchers. For example, Dr Barnard (again) whose treatment of diabetics using a wholefood, plant-based diet with neither calorie nor carbohydrate restriction led to weight loss in his patients.
Another example is the study presented in the 2015 paper
Calorie for Calorie, Dietary Fat Restriction Results in More Body Fat Loss than Carbohydrate Restriction in People with Obesity. In this study, the researchers carefully compared fat restriction to carbohydrate restriction in a metabolic lab for 19 obese adults and concluded that
fat restriction led to about 68% greater weight loss than carbohydrate restriction - a statistically significant difference with p = 0.002.
Professor Noakes also asserts that "
Humans have no essential requirement for carbohydrate". Even if this were true (doubtful), a nutritionist I know has used the following analogy: this is like saying with respect to transport that we have no essential requirement for cars. Sure, you
could get around just by walking, but a car's going to get you there a lot faster and more efficiently. Similarly, we
could just rely on fats and proteins for energy, but our bodies utilise the energy from carbohydrates a lot faster and more efficiently.
David, you shared the very impressive description of Professor Salim Yusuf. Another man with a very impressive description is T. Colin Campbell, who has published over 300 papers, has been the Jacob Gould Schurman Professor Emeritus of Nutritional Biochemistry at Cornell University since 1985, and was one of the lead researchers in the 1983 China-Cornell-Oxford Project on diet and disease, described by The New York Times as "
the Grand Prix of epidemiology". Dr Campbell
does specialise in nutrition, as opposed to Professor Yusuf, who specialises instead in cardiology - for which I don't, by the way, "damn" him: it's a related field, he's put in the work to conduct a huge study, and he's obviously read at least some of the literature in nutrition, all of which counts for something. But specific expertise in nutrition would have counted for a lot more, and might have prevented him from buying into popular misconceptions about Dr Ancel Keys and the Seven Countries Study.
Here's a video in which Dr Campbell discusses his findings from over 50 years of working in the field:
At about 45:30, he presents a slide summarising the findings of one study which reflect his overall message (caps in the original):
"Consuming WHOLE, PLANT-BASED foods (less total protein and fat, no animal protein) means less chronic degenerative diseases".
Again: this, of course, involves less saturated fat too, unless you binge on coconut fats/oils.
Like Professor Yusuf, Dr Campbell seems pretty sure of his facts - facts which he's researched for over 50 years.
[1] Ancel Keys and the Seven Countries Study: An Evidence-based Response to Revisionist Histories, a very useful paper for dispelling myths about Dr Ancel Keys and the Seven Countries Study.
[2] The Okinawan Diet: Health Implications of a Low-Calorie, Nutrient-Dense, Antioxidant-Rich Dietary Pattern Low in Glycemic Load - see table 2.