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Contemporary fatphobia
Butter used to be churned by hand in the old days...
Nowadays it seems all you hear is that fats are bad for your cholesterol, they make you get heart diseases and grow fat if eaten in excess. Cholesterol makes your veins become silted up and too much saturated fat is detrimental to your health. I call it: contemporary fatphobia. Also known as the "lipid hypothesis".
But have we always been thinking about fats and cholesterol in this way?
To be able to answer this question we have to go back. I herefore bring in the works of an internationally renowned fat researcher with a huge curriculum: Mary G. Enig, PhD. Enig is an expert on the biochemistry of fats, and has contributed to many scientific investigations and is the president of the Maryland Nutritionists Association. The following information concerning our present-day opinions about fats and cholesterol partly comes from an article publicised by Enig and Sally Fallon ( from http://www.westonaprice.org/knowyourfats/oiling.html#rise ).
Let's create an image of the situation then and now (from 1900 concerning the US, till now):
<< 20.000 years ago: human diet existed mainly of meats and other animal products, nuts seeds, berries and other fruits; population relatively free from CVD (studies 27,28)
10.000 years ago: introduction of agriculture, settling instead of nomadism, cattle farming and Industrial Revolution --> change of diet --> more grains
till 1900: CVD cause < 10% of total mortality;
1910: myocardial infarct (MI) and stroke are practically unknown
1930: < 3000 deaths a year in 1930 due to CVD
1930-1950: butter consumption decreases since beginning of 20th century; hardened fats (margarines) and fluid plant based oils take butter's place; flourishing of margarine industry
1950: cardiovascular diseases cause > 30% of total mortality. Greatest percentage for MI: > 500.000 deaths a year in 1960
1954: David Kritchevsky publicises an article in the American Journal of Physiology; effect of cholesterol on vegetarian rabbits: rabbits develop arterial narrowing
1954: David Kritchevsky publicises a second article, in which the favourable effect of PUFAs are described in lowering cholesterol levels
1955-1968: epidemiologic studies reveal that a) the vegetarian animal model of cholesterol processing is not valid when it comes to an extrapolation to human omnivore circumstances and b) that populations consuming more saturated fats, meat and fat than other populations show either equally many OR less events of cardiovascular disease
1970-: dominating dietary advice = preferably fluid high PUFAs oils, prudency with animal products and saturated fats and cholesterol and take plenty of carbohydrates
1980: the number of obese and diabetic people is significantly increasing
1980-now: solid reasearch make assumptions about trans fats unstable
2000: obesity and diabetes are beginning to take epidemic forms
2002: CVD is the number 1 death cause in the US, followed by cancer and stroke (source CDC: http://www.cdc.gov/nchs/fastats/lcod.htm )
2003: repeating of all of the above, but put in a different form (anti cholesterol products, more fat reduction, ongoing demonization of saturated fats despite studies that contradict current thoughts on saturated fats and cholesterol, etcetera
2005-: are we going to let this happen!?
Fortunately, there are a lot of positive sounds. The idea that dietary cholesterol would have enormous influence on our blood cholesterol, has gradually been abandonned. Also, claims on saturated fats have been increasingly nuanced over time. Ideas about trans fats have had to make way for solid scientific insights in its cardiovascular disease provoking properties.
Trans fats, saturated fats, cholesterol...What's next to be dismantled? To me, it's only a matter of time, when more of the upcoming insights in the true nature of fats and cholesterol are adopted by authoritative bodies...
What exactly is the lipid hypothesis?
The lipid hypothesis concerns two assumptions, widely taken for truths:
saturated fats are bad for your cholesterol and therefore cause CVD
dietary cholesterol raises blood cholesterol and thus make your veins become silted up
In the following scheme these two assumptions are visualized more clearly (arrow means "leads to" and is designated by 'step A', 'step B', etc)
1. Saturated fats -----> bad blood cholesterol -----> CVD
step A step B
2. Dietary cholesterol -----> bad blood cholesterol -----> CVD
step C step D
Discussion of steps A, B, C and D
Step A: "Saturated fat leads to bad blood cholesterol"
Thanks to research we now know that the blood cholesterol (LDL, HDL, etc) can be divided into different subclasses, for exaple LDL-I, LDL-II, LDL-III and so forth. As it appears, particles of different subclasses exert a different amount of damage. So the simple story of "the good HDL and the bad LDL" cannot be held. It matters which type of blood cholesterol you have.
In studies, when considering LDL cholesterol, we can distinguish between the “atherogenic lipoprotein profile” if people have LDL pattern B and the "large buoyant LDL" if people have LDL pattern A.
Pattern B comprises: high triglycerides, small dense LDL particles and decreased HDL.
Pattern A comprises: low triglycerides, large buoyant LDL particles and increased HDL.
Having high triglycerides is a known risk factor for cardiovascular disease.
These small dense LDL particles are far more better than the large buoyant ones to be taken up in the arterial tissue. Furthermore is has been shown that the oxidative susceptibility increases and antioxidant concentration decreases when LDL size gets smaller (Study 29).
Carbohydrate rich meals tend to switch this pattern from pattern A to B, giving higher triglycerid concentrations. Fat rich meals in contrast, seem to reverse this. This can easily be found in a large number of studies. Of all reviewed fatty acids by Mensink and Katan (AJCN 2003;77"1146-1155), saturated fats tend to rise the HDL cholesterol more than do any of the other fatty acids.
Dreon et al showed that more dietary saturated fat leads to larger LDL particles at a stable LDL concentration (Study 4) They also showed that when reducing dietary fat content in men from 20-24% to 20%, a shift towards LDL pattern B was induced (Study 3)
Mozaffarian et al showed in 235 postmenopausal women with a low total fat intake, that an increase in saturated fat intake was associated with a slower progression of arteriosclerosis, while carbohydrate intake was associated with a greater progression of this disease (Study 48). This information seems to be in congruence with the aforementioned findings of Mensink et al...
Step B "Bad blood cholesterol leads to CVD"
The conclusion that bad blood cholesterol supposedly provoked by saturated fats would lead to cardiovascular disease isn't valid enough. After all, who knows which blood profile exist after a diet rich in saturated fats? One could say:"But there is a lot of LDL! That's bad!". Is that so? So, what do we know about the aforementioned subclasses then? Are they A or B pattern? Ongoing investigation is showing that a different distribution in the subclasses can make the difference between being at risk of heart disease or not to be.
The meta-analysis of Mensink et al from 60 controlled trials (Study 25) brings forward the following conclusions:
the ratio of total: HDL cholesterol is a better predictor for CVD than total cholesterol by itself (the lower the ratio the better)
carbohydrates negatively influence this ratio and raise the total:HDL ratio 7 times as much as coconut oil (100% SFAs) lowers it
replacement of SFAs for carbohydrates raises triglycerides (risk factor for CVD)
carbohydrate rich diets raise a) triglycerids and b) LDL pattern B (remember? the REAL bad type)
"...the effect of carbohydrates on total: HDL cholesterol justifies some caution in the application of high-carbohydrate diets to the prevention of heart disease."
“There is evidence that not only the amount of cholesterol transported by LDL particles but also the size and density of these particles and their apo B content affects CAD risk.”
and:
“Lauric acid has the largest cholesterol-raising effect of all fatty acids, but much of this is due to HDL cholesterol. As a result, lauric acid had a more favorable effect on total: HDL cholesterol than any other fatty acid, either saturated or unsaturated”
Step C "Dietary cholesterol leads to bad blood cholesterol"
As explained under B, the total blood cholesterol level appears to be a much less thorough predictor for CVD than is total:HDL cholesterol.
But to what extent does eating cholesterol impact your blood cholesterol levels?
A 14-year cohort study (with fixed population) in 43.732 men aged 40-75 years found no relation betweeen dietary cholesterol and risk of a myocardial infarct ('heart attack')(Study 14). The available information of dietary cholesterol's effect on blood cholesterol indicates only modest effects (Study 18,26). The effect of lowering dietary cholesterol on the total:HDL ratio is negligible (Study 25).
Step D "Bad blood cholesterol leads to CVD"
Step D can therefore by itself be true, namely 'a' bad blood cholesterol leads to CVD, but this step cannot be linked back to intake of dietary cholesterol being the causal factor just like that . After all, this link is very weak (see C).
What does this imply for the level of truth for the lipid hypothesis?
The substantiation of the arguments concerning the lipid hypothesis seems to be quite weak. To be seen as valid, the newest insights in the roles of the different sorts of blood cholesterol profiles will have to be taken into acccount. My opinion in this matter:
the contribution of either saturated fats or dietary cholesterol to CVD cannot be defended if no further nuance is involved
thanks to new insights in the nature of saturated fats and cholesterol a lot of fear seems to have gotten redundant. So fat rich foods like dairy, butter, coconut oil and eggs may reclaim there original positions of healthy foods providing important vitamins such as A, D, E as well as highly nutritional proteins and vitamins.
My question to you now:"Do you believe that a dietary style involving more and carefully balanced fats and/ or fatty products with less (and better) carbohydrates, really is that detrimental to your health as is widely advocated?"
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