Issues of Concern
According to a CDC report in 2022, 47% of the adult population in the US have hypertension, and 41.9% of the population has obesity. The prevalence of chronic kidney disease is approximately 15%. Proper dietary intake and physical activity are the first steps in managing chronic medical conditions.
While focusing on the taste of food, people frequently overlook the components of dietary consumption. People often undervalue the significance of many essential micro- and macronutrients in our diets, even though small dietary changes can significantly impact one's health. A number of studies have shown associations between focusing on specific nutrients and improvement in health outcomes, such as hypertension, dyslipidemia, the progression of chronic kidney failure, obesity, etc.
Sodium
Sodium acts as a mediator that leads to increased blood pressure through various mechanisms. Nonetheless, people often fail to recognize how much salt is consumed daily, especially in the western diet. Reduction in dietary sodium is commonly recommended by health care providers to lower blood pressure. World Health Organization (WHO) recommends a salt intake of less than 5g per day, which is approximately 2g of sodium.
Over 100 studies have shown a direct relationship between sodium intake and elevated blood pressure. When compared to the average high sodium intake (201 mmol/day, 4.6 g per day), the average recommended sodium intake (66 mmol/day or 1.5 g per day) resulted in a reduction of systolic blood pressure (SBP)/ diastolic blood pressure (DBP) of 1/0 mmHg in White people without hypertension and 5.5/2.9 mmHg reduction in White people with hypertension.
The effect of lower sodium intake on blood pressure reduction was greater in the Black and Asian populations (4/2 mmHg reduction in Black people without hypertension and 6.4/2.9 mmHg reduction in Black people with hypertension, 0.7/1.6 mmHg reduction in Asian participants without hypertension and 7.8/2.7 mmHg reduction in Asian participants with hypertension). Participants with hypertension showed a greater decrease in blood pressure with sodium reduction.[1]
The beneficial effect of adopting a low-sodium diet in normotensive individuals is debatable. One meta-analysis study showed that the reduction in daily sodium intake was associated with a significant increase in serum cholesterol and triglyceride - serum cholesterol increased by 5.59 mg/dL and triglyceride increased by 7.04 mg/dL.[2] Another meta-analysis study showed that a low sodium diet has no adverse effect on blood lipids, including total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride.[3]
Sodium intake also has an association with kidney function. In 6 studies with 43,772 participants, higher sodium intake was associated with significantly increased odds of CKD (OR, 1.21; 95% CI, 1.06 to 1.38). CKD was defined as developing GFR < 60 mL/min/1.73 m2.[4] Lower sodium intake is also associated with lower proteinuria and albuminuria, which are strong predictors of CKD progression.[5][6] The lower sodium intake demonstrated its effectiveness in patients with diabetic nephropathy in addition to CKD patients. In addition to lowering blood pressure, it decreases urinary albumin excretion in patients with microalbuminuria and those with macroalbuminuria.[7]
Potassium
Potassium is one of the most well-known electrolytes to the general population, yet its importance is often disregarded. Multiple meta-analyses demonstrated the relationship between potassium intake and cardiovascular risk reduction. Low potassium intake has been shown to be associated with an increased risk of having higher systolic and diastolic blood pressures, stroke, and chronic kidney diseases.
Dietary potassium supplementation decreases systolic and diastolic blood pressure – 4.48 mmHg reduction in systolic blood pressure and 2.96 mmHg reduction in diastolic blood pressure. Higher blood pressure lowering effect from taking potassium supplementation was shown in the lower baseline potassium intake group ( <90mmol/day), higher sodium intake group ( ≥4g/day), and a group without any antihypertensive medication treatment.[8]
There are several proposed mechanisms of how potassium intake affects lowering blood pressure. Low potassium intake reduces sodium excretion as potassium deficiency acts as a physiological regulator of the WNK (with-no-lysine) kinase pathway, which activates thiazide-sensitive NaCl cotransporter.[9][10] Low potassium also decreases sodium excretion by activating the renin-angiotensin system.
Dietary potassium supplementation is also associated with stroke risk reduction. A meta-analysis indicated an inverse relationship between potassium intake and the risk of stroke, including hemorrhagic and ischemic origin. Higher potassium intake was associated with a 24% lower risk of stroke.[11]
The relationship between potassium intake and stroke was also non-linear, meaning that higher potassium intake did not necessarily bring the lowest risk reduction in stroke. The lowest risk of stroke was when potassium intake was around 90 mmol/day. Nevertheless, there has been no evidence that increased potassium intake adversely affects blood lipid levels, catecholamine concentrations, or renal function. The mechanism of how potassium intake may affect stroke risk requires further investigation, as it is partially explained by the effect on lowering blood pressure.[12]
Increased potassium intake is also associated with reduced odds of having chronic kidney diseases. In 7 studies with 32,647 participants, it was associated with lower odds of CKD with OR 0.78 [0.65, 0.94]. CKD was defined as developing a GFR < 60 mL/min/1.73 m2. In 4 studies with 10,729 participants, increased potassium intake also showed significant risk reduction in GFR decline with RR 0.49 [0.31, 0.79].[4]
Examples of fruits and vegetables that are high in potassium include bananas, oranges, grapefruit, raisins, potatoes, mushrooms, peas, leafy greens, etc.
DASH Diet
The dietary Approaches to Stop Hypertension (DASH) diet is a diet that was introduced in 1997 by the National Heart, Lung, and Blood Institute (NHLBI) for reducing blood pressure. It is still frequently mentioned to patients by medical providers when there is a concern for hypertension. According to NHLBI, no special foods are required in the diet plan, but it provides daily and weekly nutritional goals. The diet plan recommends consuming vegetables, fruits, whole grains, fat-free or low-fat dairy products, fish, poultry, beans, nuts, and vegetable oils while limiting foods that are high in saturated fat and sugar.
The DASH diet has been shown to be more effective at lowering systolic and diastolic blood pressure compared to a diet high in fruits and vegetables alone. The effect of lowering blood pressure was greater in the hypertensive group than in the normotensive group.[13] The DASH diet and lower sodium intake of less than 100 mmol/day both significantly lower blood pressure, with combined effects being greater than those of either one alone.[14]
In addition to the blood pressure-lowering effect, the DASH diet showed benefits in lowering the risk of developing stroke. Higher DASH diet adherence was associated with a lower risk of stroke development when compared to lower adherence (RR 0.88, 95% CI 0.83-0.93). The Asian population appeared to benefit from the DASH diet more than the Western population in terms of lowering stroke risk.[15]
Low Fat Diet
The main goal of low-fat diets is to reduce the number of calories from fat. Some strategies are very low-fat, with calories from fat comprising less than 10% of total calories, while others are more moderate, with calories from fat comprising less than 30% of daily caloric intake.
Multiple randomized controlled trials have shown that weight loss from reduced fat intake to less than 30% of daily caloric intake was greater in participants with higher body mass index (BMI) and those with lower fat intake at baseline. The reduction in body weight was also reflected in a small reduction in percent body fat, LDL cholesterol, and total cholesterol, with little to no effect on HDL cholesterol, triglycerides, or systolic and diastolic blood pressures.[16]
One randomized controlled trial showed low-fat plant-based diet intervention reduced weight by reducing energy intake and increasing postprandial metabolism, which was associated with increased insulin sensitivity.[17]
Though a low-fat diet reduces body weight and cholesterol levels, the dietary modification does not show improved survival from all causes or from coronary heart disease.[18] Furthermore, dietary fat intake should be considered carefully, as an unhealthy low-fat diet is associated with a modest increase in mortality, while a healthy low-fat diet is associated with lower total mortality.[19] Dietary fat should come from healthy sources, such as fatty fish, whole grains, non-starchy vegetables, whole fruits, and nuts.
Low Carbohydrate Diet
Carbohydrates include sugars (mono- or disaccharides), oligosaccharides, and polysaccharides, including starches and fibers. According to dietary Guidelines for Americans, it is recommended to have 45%–60% of daily energy from carbohydrates. With increasing obesity in the general population and emphasis on weight loss, more people emphasize limiting carbohydrate content in their diet.
In one randomized trial, reduced dietary carbohydrates led to an increase in energy expenditure during weight loss maintenance. Participants with a low carbohydrate diet had significantly lower ghrelin levels than those with a high carbohydrate diet, which is a hormone that increases appetite, though they also had a lower level of leptin which is a hormone that regulates satiety.[20]
Compared to a low-fat diet, a low-carbohydrate diet generally appeared to be associated with a similar rate of weight reduction in adults with obesity, when they are both associated with significant weight loss, compared to an unrestricted diet.[21]
One of the most popular low-carbohydrate diets is the ketogenic diet. The ketogenic diet consists of a high-fat, low-carbohydrate, and adequate-protein diet, with a common fat or protein-to-carbohydrate ratio of 3 to 1 or 4 to 1. Several studies have shown an anti-epileptic effect of the ketogenic diet. It is an effective non-pharmacological treatment option for patients with drug-resistant epilepsy. A pediatric group with a ketogenic diet was 5.6 times more likely to have a 50% seizure reduction than the control group after three months of the diet.[22] However, there is still debate over the effectiveness of the ketogenic diet for treating epilepsy in adults.[23]
Though the quantity of carbohydrates is often emphasized, it is essential to have quality carbohydrates by focusing on the low glycemic index (GI). Compared to low GI carbohydrates, high GI carbohydrates are broken down more quickly and induce a more rapid increase in serum glucose during digestion.
Plant-based Diet
Vegetarians and vegans represent 5% and 2% of the US population.[24] Plant-based diet refers to any diet that emphasizes eating foods made from plant sources. It focuses on increased dietary intake of fruit, vegetables, grains, pulses, legumes, nuts, and meat substitutes like soy products. People frequently have different ideas about what constitutes a "plant-based" diet. The restriction on meat products also varies between different types of plant-based diets. Some of the examples are:
- Lacto-ovo vegetarian diet: Eggs and dairy products are allowed, but all meats, including fish, chicken, pork, and beef, are excluded.
- Lacto vegetarian diet: Dairy products like milk, cheese, yogurt, and ice cream are allowed, but eggs, meat, and fish are excluded.
- Ovo-vegetarian diet: Eggs in all forms are allowed, but dairy foods, meat, and fish are excluded.
- Flexitarian diet: Diet emphasizes plant foods while small amounts of meat and other animal products are occasionally included.
- Pescatarian diet: Fish products are included, but other meats, such as beef, pork, or chicken, are excluded. It may include dairy products or eggs by personal preference.
- Pollotarian diet: Chicken products are included, but other meats, such as beef, pork, or fish, are excluded. It may include dairy products or eggs by personal preference.
- Vegan diet: Plant-based foods are included only, and all animal-derived ingredients are excluded.
Studies have shown that people with vegetarian diets, compared to those with non-vegetarian diets, had possibly lower all-cause mortality and lower risks for cardiometabolic outcomes and some cancers. Compared to an omnivorous diet, vegetarian and vegan diets are associated with clinically significantly lower BWI, total cholesterol, LDL, HDL, triglycerides, and blood glucose. Moreover, vegetarian diets were associated with a -8% reduction in the incidence of all cancer, and strict vegan diets were associated with an even higher reduction in the incidence of all cancer (-15%).[25]
Compared to lacto-ovo-vegetarian diets, strict vegan diets appear to offer some additional protection against obesity, hypertension, type-2 diabetes, and cardiovascular mortality.[24] Males appeared to have more beneficial results from having plant-based diets.[26]
In terms of mental health, vegetarian and vegan diets are generally not linked to different outcomes. Although there is no statistically significant difference in other aspects of mental health, such as stress, memory loss, degrees of well-being, etc., vegan and vegetarian diets are associated with reduced anxiety levels. They are also associated with a higher incidence of depression only in a subgroup under 26 years of age.[27]
High Fiber Diet
Dietary fibers include the types of plant-based carbohydrates that the human body cannot digest or absorb. Nowadays, the importance of fiber in a balanced diet is often emphasized. According to the United States Department of Agriculture, more than 90% of women and 90% of men do not meet the recommended amount of daily fiber, largely due to the underconsumption of fruits, vegetables, and whole grains. Some foods rich in fiber include flax seeds, leafy greens, avocado, mushrooms, raspberries, or other fruits, vegetables, and grains.
One meta-analysis showed that a higher dietary fiber intake of 35 g in patients with prediabetes and type 1 or type 2 diabetes mellitus, compared to a lower fiber intake of 19 g, showed a clear dose-response relationship with many different positive health outcomes. Over the average period of 8.2 years, higher fiber intake reduced lower HbA1c (mean difference (MD) -2.0 mmol/mol), total cholesterol (MD -0.34 mmol/L), LDL cholesterol (MD -0.17 mmol/L), BMI (MD -0.36), C-reactive protein (standard MD -2.80), when compared to lower fiber intake. These results suggest that increasing daily fiber intake by 15 g to 35 g may be a reasonable dietary change that would be expected to lower the risk of premature mortality in adults with diabetes.[28]
The benefit of increased fiber intake is also seen in patients with established cardiovascular diseases. Studies with patients with previous first-time myocardial infarction (MI) showed that increased fiber consumption from before to after MI was significantly associated with lower all-cause and cardiovascular mortality.[29] Moreover, one meta-analysis showed that increased dietary fiber was associated with a lower risk of the first stroke.[30]
The high fiber intake may also lower the risk of diverticular disease. In one meta-analysis, people who consumed 30 g of fiber daily were shown to have a 41% lower risk of having diverticular disease than people who consumed only 7.5 g of fiber daily.[31]
Clinical Significance
This activity focuses on some of the well-known dietary elements that can significantly affect health in the general population.
Sodium-restricted diet is associated with a significant reduction in blood pressure, more prominently in the hypertensive group than in the normotensive group. The benefit is shown to be greater in the Black and Asian populations compared to the White population. Adopting a low-sodium diet in normotensive individuals is debatable. While it is not as effective in reducing blood pressure as the hypertensive group, some studies argue that it increases serum lipid and triglyceride levels. Higher sodium intake was shown to be associated with increased odds of having chronic kidney disease, while lower sodium intake was associated with lower proteinuria and albuminuria, which are strong predictors of having chronic kidney disease.
Potassium is also associated with effects on blood pressure. Studies have shown that when it is taken at about 90 mmol/day, it has shown the greatest effect on blood pressure and stroke risk reduction. Higher potassium intake does not necessarily bring the lowest risk reduction in stroke. Increased potassium intake is also associated with a lower risk of chronic kidney diseases and a reduced glomerular filtration rate.
While there is no universal definition of a low-fat diet, it generally refers to daily calorie intake from fat less than 30% of total calories or a very low-fat diet with calories from fat less than 10% of total calories. The low-fat diet has shown greater weight loss in individuals with higher BMI and lower fat intake at baseline. It is also associated with increased insulin sensitivity. When adopting a low-fat diet, it is important to have dietary fat from healthy sources, such as fatty fish, whole grains, non-starchy vegetables, whole fruits, and nuts.
Carbohydrates usually take up 45-60% of the total calorie intake in the general population. Reducing dietary carbohydrates is associated with increased energy expenditure during weight loss maintenance. Low-carbohydrate diets and low-fat diets generally have a similar rate of weight reduction in adults with obesity. Anti-epileptic effects were shown in the ketogenic diet, which can be used as an effective non-pharmacological treatment option for patients with drug-resistant epilepsy, especially in the pediatric population. Carbohydrates with lower GI index should be consumed more often as it has a slower increase in serum glucose.
Plant-based diets have multiple subgroups, such as lacto-ovo vegetarian, flexitarian, pescatarian, proletarian, vegan, etc. Compared to a non-vegetarian diet, vegetarian diets are shown to have possibly lower all-cause mortality and lower risks for cardiometabolic outcomes and some cancers. They are associated with lower BWI, total cholesterol, LDL, HDL, triglycerides, and blood glucose. Males appeared to have more beneficial results from adopting vegetarian diets.
Increased dietary fiber intake is associated with lower HbA1c, total cholesterol, LDL cholesterol, BMI, and C-reactive protein. It also has a beneficial effect in lowering all-cause and cardiovascular mortality, especially in patients with previous first-time myocardial infarction. Increasing daily fiber intake to 35 g can be beneficial.
Dietary Lifestyle Changes