DEFINING A HEALTHY DIET: PART 2 - EPIDEMIOLOGICAL DIETS
Medically Reviewed by Dr. Sony Sherpa (MBBS) - September 13, 2024
Part 1 discusses dietary guidelines and components.
Part 2, Part 3, Part 4 & Part 5 reviews 24 popular diet plans across 7 major dietary categories.
Part 6 concludes the review with the debunking of common dietary myths and a summary of the key findings.
Review of 24 Diet Plans Across 7 Diet Categories
The above points highlight how every individual has a unique biology and that it can be enhanced by certain diets or detracted by others.
It is also important to note that all the best diets place an emphasis on consuming a variety of healthy, unrefined whole foods that are high in nutrient-dense fresh fruits and vegetables[1]. Most of the evidence points towards these factors as being the cause of the potential health benefits offered by any properly constructed diet plan.[2]
Variances in sources of protein and fats, grain, nut, and seed intake, as well as the type of fruits and vegetables consumed, make all of the following diets unique.
With this in mind, the following section will attempt to review several popular dietary patterns.
Diets are divided across their respective categories as follows:
- Epidemiological diets: Mediterranean, Nordic and Asian Diets
- Evidence-based diets: Paleo, DASH, MIND, Mayo Clinic, and Raw Food Diets
- Diets Designed for Specific Health Conditions: Auto-Immune Protocol/Elimination, Low FODMAP, Gluten Free, and Low GI Diets
- Protein-heavy diets: Dukan Diet
- High-fat diets: Ketogenic and Atkins Diets
- Diets that focus on calories and carbs: Zone, South Beach, Weight Watchers, Volumetrics, Nutritarian and Macrobiotic Diets
- Plant-based diets: Vegetarian, Vegan and Flexitarian Diets
Epidemiological Diets
The following diets arose from the traditional diets of people in specific parts of the world. Epidemiological studies highlighted the health of people staying in the regions mentioned below and then investigated their diets to see what they were consuming.
General advantages of consuming traditional ancestral diets from specific regions typically include improved cardiovascular and metabolic health. The way in which these benefits are achieved differs significantly from region to region. Furthermore, these diets are generally easy to follow, more palatable, and less restrictive than other diets.
One common pitfall of diets based on epidemiological evidence is that they may not be as effective for individuals residing outside of these areas. Environmental factors have been proven to alter the nutritional composition of foods belonging to the below diets, as well as changing the way in which they might affect people in different regions of the world.
1. Mediterranean Diet
The Mediterranean Diet came into being from observing that those in this region had better health and less prevalence of heart disease and diabetes[3]. This diet was described more than 50 years ago by Ancel Keys and denotes the traditional diets of Mediterranean people from that time. The average diet of those currently living in the Mediterranean is more in line with a Western diet and no longer reflects the traditional diet.
The people of the Mediterranean consume a diet high in local fresh produce, which includes fish, olive oil, nuts, seeds, legumes, Mediterranean fruits and vegetables, as well as grains, breads, and pasta. In general, the diet’s emphasis is on creating meals based on these plant-based Mediterranean foods.
Low amounts of meat, dairy, and other animal products are tolerated, as long as cooking is done with unsaturated plant-based oils (preferably olive oil!). Red meat is limited and eaten less often than poultry, eggs, and fish.[4] [5]
The Mediterranean Diet emphasizes consuming proper nutritious meals as much as possible. Preliminary evidence suggests that dietary advantages may be enhanced if implemented using only organic produce.[6]
Foods high in artificial additives, salt, sugar, refined grains, or refined fat, such as junk food, ought to be eaten in moderation, if at all. Moderate daily red wine consumption with meals is accepted on the Mediterranean Diet (but not a requirement!).
Advantages
A properly varied Mediterranean Diet is rich in nutritious foods that are typically high in fiber, low-starch carbohydrates, and monounsaturated plant oils. It is low in protein and promotes avoiding high glycemic foods.
This dietary pattern has given rise to the following advantages[7] [8] [9]:
- Reduces Low-Density Cholesterol levels.
- Protects against excessive inflammation, cellular oxidation and damage[10].
- Enhances cardiovascular health and reduces the risk of excessive blood clotting and heart attacks.
- Lowers the risk of type 2 diabetes, tumors, cardiovascular disease, and obesity.
- Promotes overall longevity.
- May help to better preserve cognitive function throughout the aging process.
- Improves microbial diversity in the gut.
- May improve bone mineral density in the elderly population[11].
- More effective than a simple low-protein diet for kidney disease.
- May enhance many aspects of cellular function by improving Sirtuin activation and positively affecting cellular metabolism. [12]
- Could contribute towards better blood circulation through increasing vascular nitric oxide, which promotes vasodilation.
- May increase the lifespan of immune cells and thus facilitate better immune function.
One study showed that the Mediterranean diet lowered the need for polypharmacy amongst the elderly, reducing the possible adverse effects of drug use.[13]
Disadvantages
The Mediterranean Diet has very few known disadvantages when compared to other diet plans. This is why it is consistently voted as one of the top 10 healthiest diet plans in many health forums.
A few disadvantages of the diet include[14]:
- Limited or episodic adherence, resulting in diminished results.
- Over-consumption of fats, even healthy fats like olive oil, can lead to weight gain when not kept in balance with physical activity or energy expenditure.
- Too much red wine may pose a risk for health conditions (especially liver conditions), in spite of having a potential cardio-protective effect.
- Sensitive individuals may respond negatively towards grains.
Lastly, the diet may not be suitable for someone who is deficient in amino acids or other essential proteins. It may not be a good idea for someone with either a muscle-wasting disease or demyelinating disease for similar reasons.
2. Nordic Diet
The Nordic Diet originates from the traditional cuisines of Nordic cultures and includes the pre-modern dietary habits of those from Finland, Sweden and Norway.
The diet is high in fish from both fresh and saltwater sources, as well as wild foods found natively in these regions[15]. It maintains an emphasis on seasonal plant-based whole foods[16], particularly berries, deciduous fruits (like apples and pears), nuts, seeds, legumes, cruciferous vegetables and root vegetables. Traditionally, fermented wheat and rye breads are readily consumed, as well as other traditional grains like oats, vegetable oils and eggs.
Processed foods, sugary foods, desserts, and meat intake (excl. fish) are limited. Of meat products consumed, wild game and poultry are preferred. Those following the Nordic Diet tend to consume low-fat dairy or traditionally fermented dairy products. Alcohol is consumed and no particular restrictions are put in place, aside from drinking in moderation.
Sodium intake is low on this diet, while the level of nutrition exceeds average dietary requirements.[17]
Advantages
The diet has only been highlighted for its health-promoting effects in recent years, and more research is required in order to get a full picture of the benefits and risks associated with a traditional Nordic Diet.
The following advantages have been revealed across several studies looking at the Nordic Diet:
- Reduces heart disease and heart attack risk.
- Decreases all-cause mortality.
- Lowers low-density cholesterol levels.
- Men consuming a Nordic diet may have a reduced risk of stroke.
- The diet may confer protection against diabetes type 2[18].
Disadvantages
The currently tested standardizations for the Nordic Diet do not accurately match the full traditional cuisine of the Nordic people. Certain foods that should be considered a traditional part of the diet have been excluded for health promotion reasons, including butter and cheeses. Current evidence points towards the health benefits of these foods when produced in a traditional manner and kept unrefined.
In this respect, scientific understanding of the Nordic Diet is limited, and therefore, results may vary.
Increased fish consumption may cause mercury toxicity; however, some fish are lower in mercury and higher in omega-3 fats than others. Omega-3 fats and many beneficial phytochemicals found in herbs, spices and other whole foods may help offset the negative consequences of ingesting too much fish.[19] [20]
3. Asian Diet
Asia is massive, and as such, there is no standardization for an Asian diet plan. When people refer to the “Asian Diet,” they may be referring to any number of dietary patterns originating from India, China, Malaysia, or any other Southeast Asian country. As such, there are a few similarities between these regions, such as a greatly increased consumption of rice, fermented foods, and Asian spices like turmeric, ginger, spicy peppers, and chili.
Like other diets listed in this section, most traditional Asian diets also place an emphasis on plant-based foods with a reduced meat intake as compared to the Western diet. A traditional Indian diet is likely to be vegetarian, with the inclusion of exotic dairy products such as yogurt and cottage cheese. Diets from other Asian countries are likely to have an increased fish consumption, particularly if coastal. Inland areas are likely to have an increased pork and poultry consumption, which may or may not be the healthiest choice for many wanting an optimal diet plan.
Other foods that commonly form part of a traditional Asian Diet include seasonal fresh fruits, lots of dark leafy green vegetables and cruciferous vegetables, exotic mushrooms, legumes and beans, nuts, seeds and sea vegetables. Vegetable, nut and seed oils are used to cook with, such as sesame, peanut and coconut oil. Pickled and fermented vegetables, such as kimchi and fermented bean pastes, are commonly used as condiments at the table.
Asian populations use spiritual, philosophical and ancestral medical observations to keep their dietary habits balanced[21]. Ayurvedic principles tend to govern an Indian Asian Diet, while traditional Chinese medicine governs the principles of many other Asian diets. In both cases, foods are broken down into basic elements (dry, wet, hot and cold foods; food flavors; acid-base ratios, etc.[22]) that ought to be consumed in balance to maintain optimal nutrition. Caloric restriction, eating only as much as one needs in order to be full, and sharing food in a social context with friends, family and loved ones are other aspects of an Asian diet that promote nutritional balance.
Advantages
The following advantages are highlighted for those following a healthy traditional Asian diet:
- Improved cardiovascular health parameters with lower low-density cholesterol levels[23].
- Asian spices have potential health benefits that may promote increased longevity.
- Traditional Chinese eating patterns may help to regulate blood pressure and promote an optimal BMI[24].
- May enhance well-being and quality of life for the elderly[25].
- Bone mineral density may improve while on a traditional Chinese diet[26].
- An increased consumption of phyto-estrogens, particularly from soy products, may help to prevent prostatic problems and certain types of reproductive cancers[27].
Disadvantages
The following disadvantages are associated with following a traditional Asian diet:
- Following an Asian diet may produce greatly mixed results, as there is no standard dietary pattern to follow.
- The Asian population appears to be exposed to a greatly increased level of heavy metals, which experts suspect is related to industrialization, rice farming, and depletion of ground nutrients. Following an Asian diet may, therefore, be healthier in regions outside of Asia, as evidenced by US dietary data of both US Asians and immigrants.[28]
- The Asian diet tends to contain high levels of foods with goitrogens. Goitrogens are phytochemical compounds that promote the formation of a goiter.
- Some Asian populations are at an increased risk of acquiring obesity[29] [30] and certain types of cancer[31] based on the oils they consume. These populations tended to consume a higher amount of refined foods than what a traditional Asian diet proposes.
- Heavy soy consumption may decrease estrogen levels in non-menopausal women[32].
NOTE: Most of the disadvantages of following an Asian diet arise from the vast deviation seen across the continent, which is conducive to misapplication of Asian health principles. When the diet is constructed in a balanced, healthy manner in line with core traditions, many of the above disadvantages fall away.
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