As we saw in last week's article, saturated fats have been maligned for decades all because of faulty science that has misshapen our opinion of them. What is the truth about saturated fats? What does the latest data and research tell us about Saturated Fats? In this week's article we seek to answer these questions.
Before we dig into the topic, some definitions need to be clarified. Specifically, there are three types of study formats that are generally used in nutrition science.
1. Randomized Controlled Trials (RCTs) are considered more rigorous in the structure of the trial and are therefore more reliable in informing nutritional recommendations.
2. Epidemiological or Observational studies are designed to show correlation between sets of data and can is therefore not meant to inform nutritional recommendations. They are only meant to form a hypotheses that can later be confirmed with RCTs.
3. A meta-analysis takes available data from multiple studies and compiles them into one, large data set. That data is then analyzed for outcomes.
What does the science tell us regarding saturated fats? The best available RCT data that we have clearly do not support the allegation that saturated fats cause cardiovascular mortality or total mortality. Moreover, a meta analysis of the non-controlled, observational evidence consistently find no association between saturated fat and cardiovascular disease.
In medical studies, the most common, reliable, and definitive end point used is 'mortality.' Simply put, mortality is used as an endpoint in attempts to answer the question, "Does this particular intervention save lives?" In this article, the intervention we are are analyzing whether decreasing saturated fat in the diet saves lives.
What does the best available data tell us about that intervention?
There have been eight meta-analyses of the RCT evidence looking at mortality outcomes. Of those eight, seven concluded that saturated fats have no effect on cardiovascular or total mortality. The eighth review found that saturated fats had an effect on CVD mortality, but this can be explained by its inclusion of a trial, called The Finnish Mental Health Study, which, as mentioned in last week's article, was non-randomized and poorly controlled and should therefore, not be classified as an RCT.
In fact, there is significant evidence that demonstrates the opposite- that restricting one's diet of healthy saturated fats can cause more harm than good. Moreover, officials risk doing harm to populations by limiting saturated fats. These fats consistently raise the “good” HDL-C and are the only food known to do so.
Several meta-analyses of all to the epidemiological data available, which includes several hundred thousand patients, found that saturated fats are not associated with heart disease. Of those meta-analyses, the largest and most global study, recently published in the prestigious medical journal, The Lancet, found that those who ate the largest amount of saturated fats had significantly reduced rates of mortality and that a low consumption of these fats (6-7% of calories, as commonly recommended for people with heart disease) was associated with increased risk of stroke.
The largest, most expensive trial ever done on this particular intervention is the Women's Health Initiative, which studied 49,000 women, asking half of them to eat low fat, low saturated fat diets with less mean, more vegetables, more fresh fruits, and more whole grains. After completing six years on this diet, these women had lowered total fat consumption and saturated fat consumption by 25% and had lowered their total and LDL cholesterol levels below that of the other half of the women, who continued their normal diets. What were the results of this study? As the final report states, the intervention had NO beneficial effect on heart disease, stroke, breast cancer, or colon cancer. Eating less total fat and saturated fat had no observable beneficial effect at all!
The verdict: The best scientific evidence available overwhelmingly indicates that saturated fats are NOT bad for you. In next week's article we will look at the significant evidence available to indicate that avoiding saturated fats, is in fact, harmful for your health.
In future articles, we will look at the difference between healthy and unhealthy fats, the benefits of eating a diet rich in healthy fats, and what the science tells us about these diets. Stay tuned!
Dr. Ram, Pharm.D.
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