Is eating seaweed good for your health?
Eating seaweed regularly or taking it as a supplement has shown measurable benefits in people for blood pressure, blood sugar control, body fat and LDL cholesterol. The effects are modest but consistent, and strongest in people who already have an elevated risk.
Seaweed naturally contains more health-promoting substances than most ordinary farmed crops: dietary fibre, omega-3 fatty acids, essential amino acids, and vitamins A, B, C and E. It also contains unique compounds found nowhere else, such as certain proteins and sugar chains. Experiments with cells and animal studies suggest antiviral and anti-cancer properties, but whether this also applies to people has not yet been demonstrated.
For blood pressure, there are positive results in people. More than 3 grams of edible algae per day for at least 12 weeks lowered the upper blood pressure reading by an average of 2 mmHg and the lower reading by nearly 2 mmHg. Spirulina performed the strongest: the upper blood pressure reading fell by an average of 5.28 mmHg and the lower by 3.56 mmHg. The effect was greatest in people who already had elevated blood pressure.
Brown seaweed, particularly in supplement or extract form, had modest but measurable effects on weight and cholesterol. After a minimum of 8 weeks, body fat percentage fell by an average of 1.48 percentage points in people with excess weight. LDL cholesterol, the "bad" type that raises your risk of heart and blood vessel disease, dropped noticeably. HDL cholesterol and triglycerides did not change appreciably.
On the subject of blood sugar, an analysis of 23 studies found that seaweed supplementation clearly improved blood sugar after meals and a long-term measure of blood sugar control (HbA1c), as well as the body's sensitivity to insulin. Fasting blood sugar did not change noticeably. A dose of 1000 mg or more per day produced the strongest effects.
A word of caution: how safe and effective the beneficial compounds in seaweed actually are with long-term use in people has not yet been studied sufficiently. If you are using seaweed as a supplement to address a health concern, it is worth discussing this with your doctor.
This answer is based on several analyses that brought together the findings of dozens of studies in people, including analyses of 29, 23 and 11 studies respectively. These provide reasonable confidence about the effects on blood pressure, blood sugar and body composition. The researchers themselves point to high variation between studies (for blood pressure) and to still-insufficient evidence on the safety of isolated beneficial compounds from seaweed over time.
Does eating fish help your heart and your brain?
Two portions of oily fish per week, as part of a varied and plant-rich diet, is a smart choice for most people when it comes to both heart and brain health. However, fish does not work as a standalone protective food.
Is eating organic food really healthier?
Eating organic demonstrably leads to lower pesticide exposure and less contact with antibiotic-resistant bacteria through meat. Whether this translates into less disease in the long run remains unclear.
Is farmed fish just as healthy as wild fish?
Three to four portions of fish per week is healthy for most people. Whether farmed fish and wild fish are nutritionally equivalent is not addressed by the available studies.
How healthy are yoghurt and dairy for your heart and bones?
Yoghurt and dairy are a perfectly good choice for bone health for most people, and are likely neutral to mildly beneficial for the heart. Opt preferably for fermented products such as yoghurt, and keep an eye on your total saturated fat intake if you have an elevated cardiac risk.
Does the Mediterranean diet help you live longer?
People who closely follow the Mediterranean diet die prematurely less often on average, although a cause-and-effect relationship has not yet been definitively proven. The strongest signal is seen in older adults and in deaths from heart and blood vessel disease, and the diet is in any case safe and broadly applicable.
Is green tea really as healthy as they say?
Green tea as a drink is safe and possibly mildly beneficial, but solid evidence for major health benefits is still lacking. Concentrated supplements are not risk-free and deserve more caution.