Statista surveyed 10,085 participants in the U.S. between July 2023 and June 2024 about the diets or nutritional guidelines they follow.
- 52% do not follow any nutritional rules.
- 17% follow low-carb or no-carb diets.
- 11% avoid dairy products or those containing lactose.
Of course, we do not know the motivations behind these choices. Do they stem from health conditions (like lactose intolerance), weight loss efforts, or a desire for a healthier lifestyle?
Research involving an online survey of 1,005 Americans published in 2022 by the International Food Information Council (IFIC) found:
- 52% of Americans reported following a diet or eating pattern in the last year, a significant increase compared to previous years.
- The most common diets were clean eating (16%), mindful eating (14%), calorie counting (13%), and plant-based diet (12%), with low-carb coming in seventh place (6%).
- The primary motivations were long-term health protection (35%), weight loss (34%), and feeling better and having more energy (31%).
Based on these two surveys, we might conclude that diets and nutrition capture significant interest from the general population, and there is a notable difference in the types of diets people follow. While the Statista survey highlighted low-carb diets, the IFIC survey emphasized clean eating.
The public, lacking expertise, turns to sources like Dr. Google for information, which may lead to questionable quality information based on the website or influencer they follow.
Diets: There’s No Shortage of Options
We can define a diet as a regime or plan designed for a specific individual, considering their objectives along with unique physical, socioeconomic, and cultural characteristics. While this definition is straightforward, identifying the "best" dietary strategy among the many available options without professional help can be challenging.
For instance, U.S. News Health published their ranking of 30 varying diets as the Best Diets in 2024. Among their criteria:
- Nutritional completeness
- Health risks and benefits
- Long-term sustainability
- Evidence-based effectiveness
- Strengths and weaknesses of each diet
- Specific objectives that each diet could meet more effectively
The top three “overall” diets included the Mediterranean diet (rich in vegetables, whole grains, olive oil, fish, and minimal red meat), the DASH diet (similar to the Mediterranean diet but with lower sodium intake), and the MIND diet (a combination of the Mediterranean and DASH diets aimed at preventing cognitive decline).
While this ranking reflects expert opinions, it is not definitive scientific evidence of the healthiest diet.
Which is the Healthiest Diet?
Given the Mediterranean diet's reputation as the “best diet in general” and its frequent praise in news reports for its health benefits, a systematic review and meta-analysis is particularly useful for addressing this question.
Published in the British Medical Journal in 2023, this review aimed to determine the relative effectiveness of structured diet programs and healthy behavior programs in preventing mortality and major cardiovascular events (MACE) in patients at increased risk of cardiovascular disease.
The analysis included only randomized clinical trials that involved a minimum of nine months of intervention in adults with cardiovascular disease or two risk factors that compared a structured dietary program and reported MACE. These structured dietary programs might include non-dietary interventions, such as exercise, psychosocial support, or behavioral support, as well as smoking cessation and drug treatments.
In total, 40 studies were deemed adequate, involving 35,548 participants. The average follow-up duration was three years. [1] The dietary programs included:
- 18 studies adopting a low-fat dietary program
- 6 studies using a very low-fat dietary program
- 4 studies employed a combination of low-fat and low-sodium diets
- 6 studies followed a modified fat diet
- 12 studies utilized the Mediterranean diet
- 3 studies used the Ornish diet, basically a plant-based diet
- 1 study used the Pritikin diet, emphasizing unprocessed foods
The quality of studies examining the sole effect of diet was reduced for low-fat and Mediterranean dietary programs because of co-interventions and in two studies that had indirect estimates of their impact.
- Evidence showed that the Mediterranean dietary program was superior to minimal intervention in reducing all-cause mortality. Participants who followed the diet were 28% less likely to die. That benefit increased as the patient’s risk rose.
- The Mediterranean diet was also superior in reducing cardiovascular mortality, nonfatal myocardial infarction, and stroke.
- Evidence showed that the low-fat dietary program was superior to "minimal intervention" in reducing all-cause mortality. Participants who followed this diet were 16% less likely to die from any cause. This diet was the only one that reduced the incidence of unplanned cardiovascular interventions.
- The combined low-fat, low-sodium diets demonstrate benefits in reducing stroke risk in high-risk patients.
- When controlling for covariates such as physical exercise, support in stress management, smoking cessation, and medication treatment, there were no substantial differences in dietary outcomes.
The authors conclude that dietary programs promoting Mediterranean and low-fat diets – with or without physical exercise or other interventions – can reduce all-cause mortality and nonfatal myocardial infarction in older patients at increased cardiovascular risk. However, there is no convincing evidence that the Mediterranean diet is superior to the low-fat diet in preventing these outcomes.
Nonetheless, before increasing your intake of olive oil, omega-3-rich fish, and whole grains while reducing red meat consumption, which remains good advice, it is important to acknowledge that the study had some significant limitations.
The main limitation of this review is the inclusion of dietary programs with co-interventions, such as drug treatment and smoking cessation, which makes it difficult to identify the actual role of the diets in the observed outcomes. If these co-interventions had been provided to both the control and intervention groups, this would have reduced the risk of bias. Additionally, the researchers highlight the difficulty in analyzing adherence to dietary programs.
An Inconvenient, Inconclusive Conclusion
Based on the evidence presented in the review and its limitations, the question of which diet is the healthiest remains open. While this may be a disappointing conclusion, it is the most realistic.
What can be inferred is that a balanced and structured diet based on generally healthy foods is likely more effective than doing nothing or very little when considering healthful choices. However, the precise composition of such a diet, let alone personalizing it to your needs, still requires further exploration.
Ultimately, the review aligns with common sense: healthy eating is just one component of a healthy lifestyle. A lifestyle that includes physical exercise, stress reduction, smoking cessation, and, when necessary, drug treatment, all actions that reduce mortality and cardiovascular risks – something quite obvious, by the way.
[1] Regarding methodological quality, 13 studies were classified as having a low risk of bias, while 27 studies were classified as high risk.
Source: Comparison of seven popular structured dietary programmes and risk of mortality and major cardiovascular events in patients at increased cardiovascular risk: systematic review and network meta-analysis. BMJ DOI: 10.1136/bmj-2022-072003.
