From the Guidelines

Garlic and lemon have no direct, established effects on hypertension, cardiovascular health, and hypercholesterolemia.

The provided evidence focuses on lifestyle modifications for hypertension, including:

Reduced salt intake: Strong evidence supports a relationship between high salt intake and increased blood pressure 1.
Healthy diet: A diet rich in whole grains, fruits, vegetables, polyunsaturated fats, and dairy products can help reduce blood pressure 1.
Weight reduction: Maintaining a healthy weight is essential for controlling blood pressure 1.
Regular physical activity: Moderate-intensity aerobic exercise and strength training can help lower blood pressure 1.
Stress reduction: Reducing stress through mindfulness and meditation can also help lower blood pressure 1.

Specific dietary approaches that can help prevent and treat hypertension include:

DASH diet: A diet that emphasizes whole grains, fruits, vegetables, and low-fat dairy products can help lower blood pressure 1.
Increased potassium intake: Consuming foods high in potassium, such as avocados, nuts, and seeds, can help lower blood pressure 1.
Moderation of alcohol consumption: Limiting alcohol intake to recommended daily limits can help reduce blood pressure 1. While garlic and lemon are not specifically mentioned in the provided evidence as having direct effects on hypertension, cardiovascular health, and hypercholesterolemia, a healthy diet that includes a variety of fruits and vegetables, such as those containing garlic and lemon, can be beneficial for overall health 1. However, the evidence does not support the use of complementary, alternative, or traditional medicines, including garlic and lemon, as a treatment for hypertension 1.

From the Research

Garlic has been recognized as an agent for the prevention and treatment of cardiovascular and other metabolic diseases, including hypertension and hypercholesterolemia 2.
Studies have shown that garlic can reduce blood pressure, waist circumference, body mass index, LDL-c, non-HDL-c, total cholesterol, triglycerides, and inflammatory markers, while increasing the levels of HDL-c 3.
Garlic has been found to have a positive effect on cardiovascular parameters, including coronary artery calcium, microcirculation, epicardial and periaortic adipose tissue, post occlusive reactive hyperemia, low attenuation plaque, carotid intima-media thickness, and carotid intima-media thickness 3.

A study found that a mixture of garlic and lemon juice can significantly decrease total cholesterol, low-density lipoprotein-cholesterol, and fibrinogen, while also reducing systolic and diastolic blood pressure and body mass index in patients with hyperlipidemia 4.
The combination of garlic and lemon juice has been shown to have a greater reduction in blood pressure and lipid levels compared to garlic or lemon juice alone 4.

Garlic has been found to have a positive impact on cardiovascular disease prevention, particularly in reducing lipid levels, although some contradictory results have been reported 5.
The inconsistent results may be due to differences in garlic preparations, variations in sulfur content, and methodological variations in subject recruitment, duration of study, and dietary control 5.
Garlic may be used as an adjuvant with lipid-lowering drugs for control of lipids, but its role as a main therapeutic agent cannot be recommended without further studies 5.

Epidemiologic studies have shown an inverse correlation between garlic consumption and progression of cardiovascular disease, with garlic found to reduce parameters associated with cardiovascular disease, including cholesterol, platelet aggregation, and blood pressure 6.
However, mixed results have been obtained in the area of blood pressure and oxidative-stress reduction, and more in-depth and appropriate studies are required to fully understand the effects of garlic on cardiovascular disease 6.