I'll do the write up on supplements and meds bit by bit in separate posts on this thread, and probably edit to add. I'll do it in this thread and then maybe re-write it all for a separate thread if people think that'd be useful. I'll start with some caveats, then list some over the counter vitamins and minerals -
Caveats: The following supplements all fairly consistently (in multiple studies) demonstrate a small reduction in both systolic and diastolic BP when taken orally, however there are a lot of caveats that need to be covered to qualify interpretation of the data.
Basically, the studies vary in the following ways: participant age, gender, concurrent health issues, underlying cause of hypertension, whether the supplement is used in combination with other supplements, whether the supplement is taken in combo with prescribed medications for hypertension or not, whether the effect was short or long term, and dosage of the supplement.
Mostly too few of the studies look in detail at other environmental factors like diet quality (and dietary provision of the discussed nutrient) exercise quantity and type, body composition of the participants or other factors like alcohol or reccy drug use (and especially not gear or PCT). Quality of the supplements used in the studies is also one area where data might be compromised in some individual studies.
There's also no real data to suggest that combining these supplements would lead to a combined reduction in BP values. Some combinations, like Magnesium and Calcium, do appear to work well in combo but not all combos are tested.
I'm putting the above out there to simply remind everyone that just because these supplements on average in a meta-analysis seem to be shown to beneficial at reducing BP, it doesn't necessarily follow that they will be for all people with high BP in all conditions.
Anyway, here is the list:
Vitamins B9 - (Folic Acid). Pooled analysis of studies suggests that 5000 μg/d or greater supplementation of B9 has a slightly beneficial effect on systolic BP (improvements between 0.43 and 3.63 mmHg) but perhaps a more clinically relevant and beneficial effect on endothelial function and vasodilation, itself an important risk reducing factor for BP related conditions.
Vitamin B2 - (Riboflavin). There are several studies that show riboflavin can drop systolic BP by a whopping 6-13 mmHg at a small dose of 1.6mg/d and in addition to the effects of concurrently taken hypertensive medications - however, this effect only works for those with the 677TT (or sometimes written as c677TT) gene variation of the MTHFR gene. Since people of this genotype will have elevated BP simply due to genetics it's a great supplement for them (and worth a try if you have elementary or primary hypertension and not had any genetic testing - high homocysteine levels is a big clue that this might work), but it also means that in non 677TT individuals who have high BP due to other causes riboflavin supplementation might not be anything like as effective directly on BP.
Vitamin C. With results varying across studies it does seem that vitamin C supplements can reduce both systolic and diastolic BP - average drops were 3.84 mmHg for systolic and 1.48 mmHg for diastolic. Doses varied from slightly lower than 500mg/d to higher. Those with high vitamin C intakes from diet showed poorer responses to supplements, suggesting that blood pressure response would not be linear if you kept increasing vitamin C intakes to higher and higher levels.
Magnesium. Again, lots of study variation, but an average daily dose of roughly 370mg of Magnesium led to an average reduction of 3-4 mmHg systolic and 2-3 mmHg diastolic BP. The method of effect was relaxation of the blood vessels. Since Mg is a known calcium channel blocker, this effect makes total sense and likely suggests it's benefit may well be additive to other supplements and medications that work by other methods to reduce BP.
Calcium. Shows fairly consistent small benefit when supplemented daily at 1200mg or more, reducing systolic values by 1.8-2.6 mmHg and diastolic values by 1-1.6 mmHg. This often seemed to work in addition to other meds and supplements. The higher end of the benefits to both BP values were seen in individuals who had very low dietary intakes of calcium generally.
Refs:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2697578/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4094332/
https://www.sciencedirect.com/science/article/pii/S0098299716300589
https://academic.oup.com/ajcn/article/95/5/1079/4576767
https://nature.com/articles/ejcn20124
https://www.nature.com/articles/1002038
Will add more later.
i ave actually been goin light headed in evenings aswel...