US heart experts analyse popular nutrition trends that are promoted for cardiovascular health

Posted on: March 07, 2017

A group of 12 heart experts looked into the scientific evidence base in nutrition and published their results in the Journal of the American College of Cardiology. The review examined several “hypes and controversies” surrounding Cardiovascular health to provide clinicians with information to aid in discussions with their patients.

In the review, the authors conclude that solid fats (at room temperature) are not recommended for reduction of atherosclerotic cardiovascular disease risk. The researchers also stated that current claims of documented health benefits of the tropical oils are unsubstantiated, and use of these oils should be discouraged. In contrast, the authors find that liquid vegetable oils have beneficial effects on lipids including decreasing low-density lipoprotein cholesterol. They did find the evidence base for olive oil as the most comprehensive, with clear evidence for a benefit in atherosclerotic cardiovascular disease risk reduction.

Limitations and interpretation
Although the advice given by the authors  to avoid trending foods and dietary hypes (including ‘juicing’, ‘coconut oil’ and ‘antioxidant pills’) seems sensible, this study has some clear limitations. The main one being the researchers ‘methods not being outlined in the review. A systematic review describing the study inclusion criteria and methodology would give greater confidence in the overall message about the state of the evidence.

Background SAFA and cardiovascular health
Dietary saturated fatty acids (SAFA), when compared to carbohydrates and cis-unsaturated fatty acids, raise plasma LDL-C, a causal risk factor for Coronary Heart Disease (CHD). Individual SAFA affect plasma lipoprotein levels differently, with each major dietary SAFA except stearic acid resulting in higher levels of LDL- and HDL-C and lower levels of TG. In recent prospective observational studies and randomized controlled trials, higher total SAFA intakes were not associated with higher incident CHD events or mortality, but replacement nutrients were not taken into account. The effect of reducing dietary SAFA is most strongly affected by the macronutrients that replace them. The greatest reduction in CHD risk occurs when cis-PUFA replace dietary SAFA. In intervention studies replacement of 10%E from SAFA by cis-PUFA reduced CVD events by 27%  and the replacement of 5%E from SAFA by cis-PUFA decreased CHD risk by 10% . Data are insufficient to confirm a significant benefit for CHD risk by substituting cis-MUFA for SAFA.

In conclusion, strong evidence supports the partial replacement of SAFA-rich foods with those rich in cis-PUFA to lower LDL-C and reduce CHD risk.