Warren Buffett set himself on a potential collision course with public health campaigners when he said it was “quite spurious” to lay the blame for obesity and diabetes at the door of fizzy drinks companies, such as his part-owned Coca-Cola.

The 85-year-old investor — and renowned Cherry Coke drinker — insisted consumption levels were a matter of personal choice as he took the stage at the annual meeting of his investment vehicle Berkshire Hathaway.

Sweet defences aside, Mr Buffett was at pains to avoid political controversy, although his caution did little to dispel enthusiasm among the almost 40,000 shareholders who made the trek to Omaha, Nebraska, a few thousand short of last year.

One attendee cited a Tufts University study last year that linked fizzy drinks to 184,000 deaths annually worldwide, and accused Mr Buffett of dodging the issue at previous meetings with jokes about his own legendary consumption of Cherry Coke doing him no harm.

“Statistically, you may be the exception,” the shareholder said, questioning whether Berkshire investors should take pride in their 9 per cent stake in Coca-Cola. “I’ve not seen evidence that convinces me I’ll be more likely to make it to 100 if I suddenly switched to water and broccoli,” Mr Buffett answered.

He decried any link between Coca-Cola and obesity-related illnesses, saying consumers have a choice over the amount and content of calories they ingest.

“You have a choice of consuming more than you use,” he said. “I make a choice to get 700 calories from Coke, I like fudge a lot, too, and peanut brittle and I am a very happy guy. If you were happy every day — and it may be hard to measure — you are going to live longer as well, so that may be a compensating factor.”

Away from the subject of his diet, the Oracle of Omaha tread a far more cautious path over the nearly seven hours of questioning that was streamed live on the internet for the first time.

His carefully calibrated answers reflect the highly charged political environment and his desire to stay aloof from debates about the influence of moneyed businessmen and even politics.

The avowed Hillary Clinton supporter went to great lengths to neutralise a gentle dig at Donald Trump — “That won’t be the main problem” he said when a shareholder asked if a Trump presidency posed risks to Berkshire — delivering a long paean to US capitalism and its guarantee of economic dynamism and growth regardless of who wins the White House.

He was similarly conciliatory towards climate scientist Jim Hansen, who spoke in support of a doomed shareholder resolution that urged Berkshire to publish a report on the risks that climate change poses to its insurance business.

The motion picked up only about 11 per cent support, on preliminary figures, after opposition from Mr Buffett. He argued that Berkshire would simply raise annual premiums if the risks materialised.

Last week, Mr Hansen wrote a public letter to Mr Buffett urging him to support policies that would put a price on carbon emissions. On Saturday in Omaha he added: “I’m not asking you to endorse a carbon fee on the spot, but I hope that you will reflect upon it. It could be your greatest legacy, it could affect everything.”

Mr Buffett responded: “We’re not denying climate change is an incredibly important subject, we’re not denying its existence. But it will not hurt our insurance business.”

Mr Buffett will regard the relative seriousness of the meeting as a triumph. He has wrestled in recent years to steer the event away from those seeking his wisdom on world events and towards the nuts and bolts of Berkshire’s business.

Questions to Mr Buffett and Charlie Munger, the company’s vice-chairman, came from the floor and from a handpicked panel of journalists and analysts. They ranged across the amount of cash held in various Berkshire subsidiaries, its share buyback policy, and the gloomy outlook for its reinsurance and railroad businesses.

Berkshire’s operating earnings declined 12 per cent to $3.7bn in the first quarter of the year because of insurance losses caused by hailstorms in Texas and sliding freight volumes in the railroad business BNSF, according to preliminary figures.

Net earnings, which Mr Buffett always warns are less meaningful, increased 8 per cent to $5.6bn because of one-off investment gains.

The full earnings statement will be released on Friday.