Best and Worst Diets for Heart Health

As we usher in the new year, many of us embark on a journey of self-improvement, often marked by the resolute commitment to adopt healthier lifestyles — swapping cookies for quinoa, potato crisps for kale chips, all washed down with a hearty glug of extra-virgin olive oil.

A common focal point in this annual pursuit of wellness is the exploration of various diets that promise transformational results. From Keto and Paleo to Mediterranean and plant-based regimens, the diet landscape is vast, each claiming to hold the key to a healthier and longer life.

Yet, amid the fervour of New Year resolutions, it’s important to cast a discerning eye on the impact these diets may have on our heart health, given that cardiovascular diseases are the leading cause of mortality in the world.

A recent publication scrutinised 10 popular dietary patterns, based on their alignment with the American Heart Association (AHA) heart-healthy guidance.

Here we summarise the findings — assessing how each of these patterns measure up and explore potential adjustments to enhance health outcomes while accommodating personal preferences and budget constraints.

The ten dietary patterns put under the microscope were: 

• DASH (Dietary Approaches to Stop Hypertension)
• Mediterranean,
• Pescatarian
• Ovo/lacto-vegetarian
• Vegan
• Low-fat (20-30% of energy from fat)
• Very low-fat (≤10% of energy from fat, exemplified by Ornish and Pritikin)
• Low-carbohydrate (20-40% of energy from carbohydrate, including Zone and South Beach diets)
• Palaeolithic
• Very low-carbohydrate/ketogenic (5-10% of energy from carbohydrate)

Beyond simply ranking diets based on their adherence to the AHA guidance, the authors spotlighted the positive attributes of these diets when followed correctly, discussed what makes them easy to adopt, pinpointed the hurdles and misconceptions that health professionals need to clear up to ensure proper adoption, and suggested strategies to boost adherence and amplify the diets’ health benefits.

The supplemental material in this paper is worth exploring, providing evidence-based summaries that define each diet’s characteristics. For each dietary pattern, the researchers aimed to identify 5 to 6 published studies that described the individual components of the diet, focusing on aspects to emphasise, include, and limit/avoid. So, it’s important to mention here that this was not a systematic review of the literature.

These summaries also highlighted the complexity of even defining these diets. Take the Mediterranean diet, for instance. Depending on which scoring system you look at, a serving of dairy might cost you points, while another might reward you for including yogurt. The truth is, there isn’t a single Mediterranean diet—what’s eaten in France isn’t the same as in Greece. But that’s the beauty of dietary patterns; they offer flexibility.

To kick things off, let's delve into the dietary guidelines outlined by the AHA to promote cardiometabolic health. The most recent guidance comprises 10 features, with the authors including 9 of these key elements in their scoring system:

1. Eat plenty of vegetables and fruits; chose a wide variety
2. Choose foods made from wholegrains rather than refined grains
3. Choose healthy sources of protein
4. Use liquid plant oils rather than animal fat and tropical oils
5. Choose minimally processed foods instead of ultra-processed foods
6. Minimise intake of beverages and foods with added sugar
7. Choose and prepare foods with minimal or little salt
8. If you don’t drink alcohol, do not start, if you choose to drink alcohol, limit intake
9. Adhere to this guidance regardless of where food is prepared or consumed

They gauged each diet using a scoring system that reflects how well they embody nine key AHA features. Full alignment scored a solid point, mostly aligned earned 0.75, partially meeting the mark got 0.5, and contrary components scored zero. It was assumed these scores reflect the diets’ ideal execution.

The diets were then sorted into four tiers based on their AHA guideline alignment. The top-tier diets closely matched the AHA’s vision and were deemed adaptable to cultural norms, personal tastes, and budget constraints, fostering long-term adherence. The second tier mostly conformed to the AHA’s advice. The third tier diets, with careful counselling, showed moderate alignment but came with inherent limitations. The fourth tier diets had a poor correlation with the AHA guidelines.

🏆  TIER 1 (The Best)

• Mediterranean
• DASH-style
• Pescetarian
• Ovo/lacto-vegetarian.

These diets closely matched the AHA’s vision and were deemed adaptable to cultural norms, personal tastes, and budget constraints, fostering long-term adherence.

They boast a bounty of vegetables, fruits, whole grains, and plant proteins.

The Appeal

Versatility. They offer a smorgasbord of wholesome foods, making it easy to find something for everyone. Notably, there's room for those who prefer some animal protein, and the inclusion of fatty fish in the Mediterranean and pescetarian patterns adds cardiovascular benefits. With minimal restrictions on food and food groups, adherence becomes more attainable.

The Challenges

Oversimplification and misinterpretation. These are common pitfalls of dietary patterns in general. For instance, overemphasising olive oil in the Mediterranean diet can overshadow its other nutritious elements. Following a pescatarian diet might lead to a menu dominated by fried fish, while an ovo-lacto-vegetarian diet could inadvertently lean towards refined carbohydrates. The authors underscore the need for some counselling to ensure a diverse intake of healthful foods like fruits, vegetables, nuts, legumes, and whole grains.

The Opportunities.

Budgeting costs. Recognising the costs associated with consuming 8-10 servings of fruits and vegetables daily, the authors offer practical strategies, such as recommending frozen or low-sodium/no-added-sugar canned varieties. And embracing legumes can be a budget-friendly way to incorporate plant protein. Moreover, the authors recommend using spices and herbs to meet DASH’s lower sodium targets and advise a gradual increase in high-fibre foods to mitigate any potential digestive discomfort, especially for those unaccustomed to fibre-rich diet.

🥈TIER 2

• Vegan
• Low-fat

Both dietary pattens mostly conformed to the AHA’s advice. They are focused around abundant vegetables, fruits, whole grains, and, in the case of the vegan diet, nuts. They also advocate for minimal consumption of sugary foods and beverages, and recommend moderating alcohol intake.

The Appeal

Do-good. A vegan diet may particularly resonate with individuals motivated by concerns for animal welfare or the environment, serving as a potent catalyst for behaviour change. On the other hand, low-fat diets are familiar with a wide array of available low-fat food products. Such diets can cut down on saturated fats, a positive step for heart health.

The Challenges

Restrictive. The authors note that the vegan diet’s restrictive nature may pose challenges for sustained adherence. It also omits certain foods like fatty fish, which are otherwise encouraged by the AHA. Those following a low-fat diet must be cautious not to substitute fats with an excess of refined sugars.

The Opportunities

Mindful Substitutions. Observations from numerous low-fat diet studies indicate adherence tends to waver, often accompanied by an undesirable shift towards increased sugar and refined grain consumption. Therefore, we should prioritise the substitution of saturated fats with polyunsaturated fats (PUFA) and monounsaturated fats (MUFA). Vegans might want to consider taking a vitamin B12 supplement or opt for foods fortified with B12, such as certain plant-based milks.

🥉TIER 3

• Very low-fat (often vegan)
• Low-carbohydrate

With careful counselling, these diets show moderate alignment with AHA guidance but also come with inherent limitations. Both dietary patternshighlight non-starchy vegetables while minimising foods and drinks with added sugar and alcohol. The low-fat regimen leans towards legumes, while the low-carbohydrate approach favours nuts and fish.

The Appeal

Health benefits. These diets can draw interest with research backing their health benefits: the very low-fat diet has been linked to stabilising atherosclerosis, and the low-carb diet has been associated with weight loss, at least in the short term.

The Challenges

Limits food groups. Yet, these diets come with their own set of limitations, as they tend to restrict certain food groups endorsed by the AHA. For instance, a low-carb diet may limit legumes, grains, and fruits, while a very low-fat diet might reduce intake of nuts and plant oils. A low-carb diet’s heavy reliance on animal foods poses the risk of elevated saturated fat intake while compromising fibre intake.

The Opportunities

Counselling. To navigate these challenges, the authors propose counselling clients to opt for the most nutrient-dense choices. Recognising that overly strict diets may lead to nutrient deficiencies, the authors advocate for a measured approach, suggesting a loosening of restrictions on certain food groups like fruits, nuts, whole grains, legumes, and seeds.

💩 TIER 4 (The Worst)

• Paleo
• Ketogenic

These diets don’t align well with the AHA’s guidelines. Their redeeming qualities? They’re rich in non-starchy veggies, nuts, and fish, and they keep a tight rein on added sugars and alcohol.

The Appeal

Quick (albeit short) fix. There’s some evidence to suggest that these diets can nudge the needle on weight, blood sugar levels, and even triglycerides, at least for the first six months. However, most of these improvements tend to be short-lived with no significant changes compared to comparison groups at 12 months.

The Challenges

Adherence. Sticking to the AHA’s playbook is a tough ask for these diets, given their exclusion of legumes and whole grains and their heavy lean towards animal foods. The restricted foods contain lots of heart-healthy phytonutrients, after all. Plus, it’s all too easy to go overboard with saturated fats and sodium on these plans. Also, the keto-flu — symptoms some people experience in the early days such as headaches and fatigue — may put people off continuing.

The Opportunities

Optimisation potential. There’s room for optimisation in these dietary patterns. By ensuring a generous intake of vegetables, fruits, and nuts, one might amplify the health perks of these diets. For the keto-curious, a guiding hand to craft a diet that’s as wholesome as possible—think plant-based fats and nuts, with a cap on saturated fats—could be beneficial. Consideration of a vitamin/mineral supplement could also be prudent in optimising nutritional intake.

👧 Rachel's Reflections

Reflecting on these diverse dietary patterns, it's crucial to recognise that there are both healthier and less healthy ways to put them into practice. Despite their diversity and the fervour of some advocates, common threads emerge—they all tend to restrict refined starches, added sugars, and processed foods while championing the consumption of whole foods. A more in-depth exploration of these themes are outline in a 2014 publication and well worth a read.

Notably, those diets occupying the top two tiers not only demonstrated healthbenefits but also exhibited a planet-friendly aspect by being lower in meat. Hence, these dietary approaches score a dual victory, aligning with both healthand environmental considerations.

In the end, it’s evident that a multitude of dietary patterns can pave the way to better health. As we've explored, certain patterns outshine others, and some require more comprehensive counselling. However, as practitioners, it's crucial for us to remain receptive to adjusting these patterns to align with individual preferences, cultural considerations, and financial constraints—all while striving to optimise health outcomes.