Mozaffarian on saturated fats

          Mozaffarian on saturated fats link

Here are some important excerpts which show the futility of advising less than 7 per cent sat fats in your diet.

"The reality is much more complex.

SFAs are heterogeneous, ranging from six to 24 carbon atoms and having dissimilar biology.

For example,

palmitic acid (16:0) exhibits in vitro adverse metabolic effects,

whereas medium-chain (6:0–12:0), odd-chain (15:0, 17:0), and very-long-chain (20:0–24:0) SFAs might have metabolic benefits.4

This biological and metabolic diversity belies the wisdom of grouping of SFAs based on a single common chemical characteristic—the absence of double bonds.

Even for any single SFA, physiological effects are complex:

eg, compared with carbohydrate, 16:0 raises blood LDL cholesterol, while simultaneously raising HDL cholesterol, reducing triglyceride-rich lipoproteins and remnants, and having no appreciable effect on apolipoprotein B,5 the most salient LDL-related characteristic.

Based on triglyceride-lowering effects, 16:0 could also reduce apolipoprotein CIII, an important modifier of cardiovascular effects of LDL and HDL cholesterol.

SFAs also reduce concentrations of lipoprotein(a),6 an independent risk factor for coronary heart disease.

Dietary SFAs are also obtained from diverse foods, including cheese, grain-based desserts, dairy desserts, chicken, processed meats, unprocessed red meat, milk, yoghurt, butter, vegetable oils, and nuts.

Each food has, in addition to SFAs, many other ingredients and characteristics that modify the health effects of that food and perhaps even its fats.

Judging the long-term health effects of foods or diets based on macronutrient composition is unsound, often creating paradoxical food choices and product formulations.

Endogenous metabolism of SFAs provide further caution against oversimplified inference: for example, 14:0 and 16:0 in blood and tissues, where they are most relevant, are often synthesised endogenously from dietary carbohydrate and correlate more with intake of dietary starches and sugars than with intake of meats and dairy.4

These complexities clarify why total dietary SFA intake has little health effect or relevance as a target. Judging a food or an individual's diet as harmful because it contains more SFAs, or beneficial because it contains less, is intrinsically flawed.

A wealth of high-quality cohort data show largely neutral cardiovascular and metabolic effects of overall SFA intake.7

Among meats, those highest in processing and sodium, rather than SFAs, are most strongly linked to coronary heart disease.7

Conversely, higher intake of all red meats, irrespective of SFA content, increases risk of weight gain and type 2 diabetes; the risk of the latter may be linked to the iron content of meats.2, 8 Cheese, a leading source of SFAs, is actually linked to no difference in or reduced risk of coronary heart disease and type 2 diabetes.9, 10 Notably, based on correlations of SFA-rich food with other unhealthy lifestyle factors, residual confounding in these cohorts would lead to upward bias, causing overestimation of harms, not neutral effects or benefits.

To summarise, these lines of evidence—

1-no influence on apolipoprotein B,

2- reductions in triglyceride-rich lipoproteins and lipoprotein(a),

3- no relation of overall intake with coronary heart disease, and

4-no observed cardiovascular harm for most major food sources—

provide powerful and consistent evidence for absence of appreciable harms of SFAs.

Yet, whereas some SFA-containing foods such as yoghurt, nuts, vegetable oils, and perhaps cheese promote health,7 these findings do not support benefits for other SFA-rich foods.

Although unprocessed red meats and butter might be neutral for coronary heart disease,

no studies demonstrate appreciable benefits;

all meats seem to increase risk of weight gain and type 2 diabetes;

and processed meats clearly do harm.2, 7, 8

This is a common mistake made by SFA enthusiasts—conflating the complexities of health effects and benefits of some SFA-containing foods, and possibly some specific SFAs, with the unsupported idea that eating a lot of butter and bacon is a route to good health.

Similarly, a common mistake made by SFA traditionalists is to consider only slices of data—for example,

1- effects of SFAs on LDL cholesterol but not their other complex effects on lipids and lipoproteins;

2- selected ecological trends; and

3-expedient nutrient contrasts."